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Quickie Questions - Astronomy - Stars & Constellations

Date Answered Questioner (age, location) Question Answer
May 10, 2010Bob (Minnesota)Is there a constlation in either the nothern or sothern skys that has a circular shape?Ophiuchus, northwest of the center of the Milky Way, has been some times drawn as having a large circular shape.
April 20, 2010Sam (NJ)Can you please tell me the Apparent magnitude, Absolute magnitude, Surface Temperature, Class, Distance from Earth, and what is it named, for the constellation HERCULES?The questions you asked apply to stars. For example, Mu Herculis is a nearby star system (about 27.4 light years from Earth) in the constellation Hercules with the following characteristics: Apparent magnitude (V) 3.42/10.35/10.80 Absolute magnitude (MV) 3.80/10.73/11.18 Mass 1.1/0.31/0.31 M¨‘ Radius 1.8/0.48/0.4 R¨‘ Luminosity 2.2-2.7/0.005/0.003 L¨‘ Temperature 5,500 K Spectral type G5 IV/M3.5 V/M4 V Hercules constellation is named after Hercules, the Roman mythological hero.
March 29, 2010Natalie (USA)Witch star is the farthest away from earth?With the Hubble telescope and using an exposure time of several hours, one can see stars to about 30th magnitude. This is about 10 billion times fainter than our Sun, if it were 32.6 light years away. Since there are 1020 or more stars within the visible universe, it is almost impossible to identify which one is farthest.
March 26, 2010EL (PHILIPPINES)HOW WERE THE CONSTELLATION OF THE ZODIAC CHOSEN?A probable cause for being chosen as the zodiac signs would be that they fall within the plane of the ecliptic.
February 23, 2010Haley (United States)What is the Greek or Roman myth that is associated with Canis Major?Canis Major is known as the Great Dog. In Greek myth, it is said that this constellation, along with Canis Minor, are Orion's hunting dogs. Canis Major was one of the most important constellations in ancient times because the brightest star in the sky is part of it.
February 9, 2010jheszabel (philippines)why is the presence of large amount of helium in the spectrum of a star generally considered to be a sign of age ?Because helium is a product of the thermonuclear fusion inside a star. Thus, an old star has lost most or all of its hydrogen, leaving just a core of helium.
February 9, 2010jheszabel dela cruz (philippines)why is the presence of large amount of helium in the spectrum of a star generally considered to be a sign of age ?Because helium is a product of the thermonuclear fusion inside a star. Thus, an old star has lost most or all of its hydrogen, leaving just a core of helium.
February 5, 2010Erica (Michigan)If the stars appear to move clockwise and counterclockwise at the Poles, how do they appear to move at the equator?Stars move couterclockwise, rising from the east and setting in the west, following a kind of rotational path around an apparent "pole" formed by the North Star.
February 4, 2010Allie (Illinois)Who and when was the virgo constellation found?The Virgo Constellation has been known for a very long time. One of the earlier mentions was by Babylonian Mul.Apin (between 686 BC and 1000 BC), who mentioned that this constellation was known as "The Furrow" , representing the goddess Shala's ear of grain or corn. More information here.
February 3, 2010lyric (illinois)who discovered the constellation ursa minorCallimachus (D.L. I.22) reported that Thales 'discovered' Ursa Minor. This means only that he recognized the advantages of navigating by Ursa Minor, rather than by Ursa Major, as was the preferred method of the Greeks. Ursa Minor, a constellation of six stars, has a smaller orbit than does the Great Bear, which means that, as it circles the North Pole, Ursa Minor changes its position in the sky to a lesser degree than does the Great Bear. Thales offered this sage advice to the mariners of Miletus, to whom it should have been of special value because Miletus had developed a maritime trade of economic importance. (Extracted from http://www.utm.edu/research/iep/t/thales.htm#SH8e)
February 1, 2010sara (Georgia)Explain what effects the fusion of hydrogen brings about in a developing star.The Sun, like most stars, generates its energy by nuclear fusion of hydrogen nuclei into helium. Nuclear fusion is an atomic reaction in which many nuclei (the centers of atoms) combine together to make a larger one (a different element). The result of this process is the release of a lot of energy.
January 27, 2010stefano (ITALIA).I see that there is a relation between the activity cycle and the rotation speed of a star.
Couldn't be that there is a relation between the activity cycle and the mass of a star too?Thank you very much.Regards.Stefano
Although the total mass of a star is the principal determinant in its evolution, I don't believe there are significant mass changes during a star's activity cycle.
January 27, 2010Nancy (tooele)Why do our constellations have myths anyway? What good will that do?Since long ago, people around the world have associated the heavens, the stars, and the patterns they make in the sky with their gods and goddesses. Links from this page will take you to descriptions of the role of selected stars, star patterns, and related gods and goddesses in various cultures
January 15, 2010miya (Michigan)what r 2 constellations scientific name and nikname that i could c n Michigan?There are many, for example, the constellations that form the Northern Circumpolar Sky are Cassiopeia, Cepheus, Draco, Ursa Major, and Ursa Minor.
January 12, 2010Gabbi (Colorado)what is special about constellationsConstellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. More information can be found in our web page Constellations.
January 11, 2010Paige (Colorado Springs/Colorado)What are some latin sources for the Roman myth of Sagittarius, and were can I find them?Some information can be found in our web page Sagittarius and in Sagittarius in Myth.
January 11, 2010Corey (Pennsylvania)What is the Spectral Class of the three Brightest stars in the andromeda constellationThe three brightest stars in the Andromeda Constellation are Alpha (Alpheratz, Spectral type B8IVpMnHg), Beta (Mirach, M0IIa), and Gamma (Almaak, K3IIb+A0V).
January 4, 2010Brenda (Georgia)Can the southern cross be seen from Jamaica/ Cayman Islands or while you are in the ocean south of Cuba?Yes!, if you live in the Northern Hemisphere, you must be south of latitude 30 degrees to begin observing Crux, one of the smallest, but most easily recognized constellations in the sky. Crux lies along the Milky Way and is surrounded by Centaurus, the Centaur, on three sides.
January 4, 2010Alexia (az)Does the constelation of Cetus still exist today?Yes, it does! Visit our web page Cetus for information on this constellation.
January 4, 2010jahnavi.s (india)who gave the stars these strange names?Most of the names we use for the stars are Arabic, Egyptian or Greek in origin, and are often tied to mythology. They generally originate from ancient times.
December 30, 2009Hunter (canada)what is the smallest star in the scorpius constellation ?The faintest star in Scorpius (so far detected) is OGLE-2007-BLG-368. It is located at least 19 200 light years away from Sun. This star has mass 0.65 solar masses which implies that it could probably be a late K-type star.
October 6, 2009siti hajar binti zulkifli (malaysia)why the stars only can be seen at night?They are there, in the sky, but because the Sun is so bright we can't see them. During total eclipses of the Sun they reappear in the middle of the day. It is a beautiful sight!
September 28, 2009Mike (New Zealand)If the CRUX points SOUTH, is it influenced by Magnetic North?I don't believe so. Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view.
September 17, 2009Kaysie (Arizona)how does the change in seasons affects the motion of the stars.The apparent motion of the stars is affected by the relative position of the observer, which changes from season to season. The following web pages offer more information about the change in position for the main constellations and its causes: As the World Turn The Changing Night Sky Northern Summer and Southern Winter Constellations Exploring the Southern Hemisphere Constellations Exploring the Northern Hemisphere Constellations
August 19, 2009Randall (Florida)How much larger is the planet Antares than Earth?Antares is not a planet, it is a red supergiant star in the Milky Way galaxy and the sixteenth brightest star in the nighttime sky. Its radius is 800 times the radius of our Sun!!!
August 19, 2009Grace (California)How far from Earth is Girtab (a star that forms the constellation Scorpius, also known as Scorpio)?Girtab distance to Earth is about 272 light years.
August 19, 2009Grace (California)How far from Earth is Jabbah?Jabbah distance from Earth is about 435 lightyears.
August 19, 2009Grace (California)How far from Earth is Shaula, a star that forms the constellation Scorpius?It has been recently determined that Shaula is "just" 365 ± 16 light-years from Earth.
July 20, 2009princess (mississippi,u.s.a)who discovered the costallation libra?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. Constellations don't have a particular finder associated with them.
July 20, 2009Jim (Ohio)Isn't Ophucius a Zodiac constellation. It meets all classifications. Is it omitted because of the "unlucky thirteen" phenomenon?The fact is that there are only 12 recognized Zodiac constellations, but it is also true that the ecliptic itself passes through an additional thirteenth constellation, Ophiuchus, situated between Scorpius and Sagittarius.
July 16, 2009deja (wisonsin)what are the celestial objects in the constellation capricorn????Capricorn has several galaxies and clusters. Messier 30 is a globular cluster located 1 degree south of the galaxy group NGC 7103. The constellation also harbors the wide spiral galaxy NGC 6907.
June 2, 2009Tyler (Deer Lodge MT)What can you tell me about draco the dragon?Draco the dragon is a circumpolar constellation. It can be seen all year round in the Northern Hemisphere. It is not visible in the Southern Hemisphere. Much more information on our web page Draco the Dragon.
May 29, 2009Abby (indiana)what is the distance between earth and cetus the constellation?Constellation are formed by stars and grooup of stars that can be at very differentdistances from our system. There are many galaxies in the Cetus constellation. One of them, M77 (NGC1068) is at 46.9 million light years.
April 28, 2009Ally (Michigan, USA)What other constellations are by Scorpius?Sagittarius is relatively closed to Scorpius.
April 17, 2009Aaron (Philippines)how does a constellation form?The shape of the constellations is more cultural that scientific. Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. Please, visit our web page Constellations and links therein for more information.
April 15, 2009Sandy (PA/USA)How is the Balmer thermometer used to determine the spectral class of a star?The Balmer thermometer is based on the fact that the star photosphere's temperature is reflected in the strength and variety of absorption lines in the spectrum. The Balmer lines (hydrogen spectrum lines in the visible) reach peak strength at a temperature of 10,000 K. These peaks arise from transitions of the electron upward out of the second energy level (second orbit). This relation is what is called the 'Balmer thermometer', which, along spectral information for other atoms, help scientists to determine the star temperature and spectral class.
April 14, 2009alyana (philippines)Is Betelguese a red giant star or a red supergiant star?Betelgeuse is a red supergiant, relatively luminous, and one of the largest stars known.
March 11, 2009Bobby (NM)Which very small constellation contains the most distant globular star cluster in the Milky Way galaxy?I am not sure if this is the right answer to your question, but I believe the farthest "cluster" of named stars inside a spherical (gravitationally influenced) Milky Way Galaxy, is the globular cluster NGC 2419 in Lynx.
March 3, 2009Gwyn (Massachusetts)I need to make a diagram of the constellation Camelopardalis. I cannot find any information on how it looks, how many stars there are in the constellation, and how many light years each of the stars are away. Can you please tell me?All the information you need can be found here and here.
February 25, 2009joseph (georgia/usa)because a blue star is much hotter than our sun would it's core consist of plasma or another form of matterAlthough blue stars are indeed much hotter than the Sun, both types, and in fact all stars, are made of plasma. In fact, plasmas are by far the most common phase of matter in the universe, both by mass and by volume.
February 20, 2009Jonathan (Texas)Does a star get colder as its life progresses?There are, at different stages of stellar evolution, changes in temperature. Over long periods of time the changes can be quite radical (both increasing and decreasing temperature).
February 2, 2009jason (NJ?USA)How do we see the constellation Cygnus during this month but not the constellation Sagittarius?There are constellations that are visible all year-round. They are called circumpolar. For example, see the The Northern Circumpolar Sky and The Southern Circumpolar Sky. Other constellations rise and set along the year.
January 22, 2009Carly (California)What is Orion's Belt?I could be related with what is known as "The Three Kings," part of the Orion constellation. Alnitak, Alnilam, and Mintaka make up the asterism known as "Orion's Belt," the three bright stars in a row.
November 6, 2008Amber (MI/ USA)What major constellation is seen in Michigan but not in Bolivia?Our web page The Northern Circumpolar Sky shows that Cassiopeia, Cepheus, Draco, Ursa Major, and Ursa Minor are all North Hemisphere constellations.
November 4, 2008Alison (Charlotte, NC)What happens to one of our constellations, if one of it's stars die? Especially one of the major ones like our astrology signs.Nothing would happen. Constellations are just formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view.
October 10, 2008Valerie (Canada)Does the zodiac sign Aries have a constellation and myth?
Thank you!
There are a couple of myths about Aries. It is said that when Bacchus and his friends were lost in the desert, they were rescued by a ram. As a reward Bacchus put the ram in the stars. See this page for more information.
September 16, 2008Jeff (Florida)How can I find the constellations that would be most prevalent in Grand Cayman August 10-17,2008. I want to be able to identify them.THXOur website offers pictures and descriptions of the Northern Hemisphere constellations, Southern Hemisphere constellations, and Sky Maps for several locations.
September 15, 2008mohd (singapore)what constellation is v shapedThe SCULPTOR constellation shape is very close to a V. See this map.
September 12, 2008Kyle (Philippines)What are the color and magnitude of stars in hercules constellation?Here is a table of notable stars in the constellation Hercules, sorted by decreasing brightness.
September 12, 2008Zita (Serbia)Is there any offical shape of the constellations? (if it is, where can I find it) I mean I found eleven kind of shape for the Lion with the same stars(or more)... Is it O.K. that everybody sees it other way?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. PLease, visit our web page Constellations and links therein for more information.
September 4, 2008Antoinette (Florida/United States)What object was used to observe the supernova in 1987The SN1987A was observed from space, on March 4-12, 1987, by Astron, the largest ultraviolet space telescope of that time.
August 25, 2008Amy (qld)what ancient civilisations used the constellions as a way of life and can you please explain how the stars influenced there lives??Almost all ancient civilizations developed myths around the shapes they saw formed by the stars. PLease, see our page Constellations and links therein for more details on this topic.
August 21, 2008Elizabeth (Texas)How far is the constellation Leo from earth?When talking about a constellation an exact distance is always hard to detrmine because constellation are formed of bright stars which appear close to each other on the sky, but are really far apart in space.
August 18, 2008Eilish (Texas, USA)At what time (cst) is the taurus constellation visible?Taurus is clearly visible in the Northern Hemisphere winter sky, between Aries to the west and Gemini to the east. It is best seen in January, at 9:00 PM.
August 15, 2008Jordan (New York)How does the position of a particular star vary from night to night in a 2 month period of time?Not enough to be detectable. It has been calculated that the position of a given stars varies at a rate of one degree in 72 years.
June 23, 2008joseph (Texas/USA)When was Aquarius discovered and who named it?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many ancient societies saw patterns among the stars with gods and goddesses or stories from their culture. More related information on this particula constellation in our web page Aquarius.
May 16, 2008nicole (philippine)can you please list down all the constellation in Northern and
Southern Hemesphere?
That would be a long list, we have compiled the information you want in our web pages Northern Hemisphere Constellations and Southern Hemisphere Constellations.
April 24, 2008Biarki (B.C. Canada)What is the legend of Leo the Lion.More than two thousand years ago, Greeks believed the god Zeus placed the figure of a gigantic lion in the sky with the rest of the stars. This lion lived in the city of Nemea. The people who lived in that region were terrorized by the Nemean Lion. Several times they tried to destroy the beast. Heracles, the most famous Greek hero, was ordered by the king, Euryshtheus, to kill the Nemean lion. Heracles was an incredibly strong man. The Romans called him Hercules. When Heracles reached the cave where the beast was living, he realized all his weapons were useless against the lion. Heracles killed the lion by strangling it with his bare hands. When the beast was dead, Heracles used its pelt as a coat and the head as a helmet.
March 27, 2008grace (missouri)what is the apparent cause of the movement of the stars?The different orbital positions of the Earth throughout the year cause us to view changes on the relative positions of the stars.
March 24, 2008Briana (Colorado)Is a Supernova hotter than the Sun?In a typical Type II supernova, the newly formed neutron core has an initial temperature of about 100 billion kelvins (100 GK); 6000 times the temperature of the sun's core. More information here.
March 18, 2008johnis there anyplace I can find the distances to stars in the sky in light yearsIn our web page Star Statistics you can find the distance to the nearest stars.
March 17, 2008vijaya (india)when we look at sky at night in winter season from the northern hemisphere ,we will see the constellation ORION,suppose if we want to look at day may be at the time of total solar eclipse ,then what can we see at day time because it's dark from the eclipse ,also what constellation we can see that time.If I understood your question, you should be able to see the constellation Scorpius.
March 3, 2008shandi (indianapolis,indiana)how many miles away from Earth is Cygnus the star?
thanks for answering my ?
The distance from our system to Cygnus X-1 is about 2500 parsecs or 8000 light years.
March 3, 2008stephanie (connetitcut)is venus the north starVenus is known as the morning and the evening star. The North Star (also known as the Pole Star) is the star that lies closest in the sky to the north celestial pole, currently Polaris.
February 15, 2008Grace (Northwood, NH)Who discovered the constellation Cepheus?Cepheus has been known since ancient times by many civilizations. Visit our web page Kin Cepheus for more information.
February 15, 2008Grace(Northwood, NH)Who discovered the constellation Cepheus?Cepheus has been known since the ancient times by many civilizations. Visit our web page Kin Cepheus for more information.
February 8, 2008lajuanda (wisconsin)where do i find the constellation leoLeo is one of the constellations visible to people living north of the equator in Spring and to people living south of the equator in Autumn. Leo is visible from February through June. Cancer sets to the east and Virgo is to the west. Hydra and Crater are below.
February 4, 2008Erin (Michigan)What are the 6 main stars in the Horologium constellation?The six main stars of the Horologium constellation (sorted by decreasing brightness) are: á Hor ä Hor â Hor ì Hor æ Hor í Hor
February 3, 2008Dorian (Indiana, USA)Are all stars in galaxies, and if not what do you call the ones that aren't??? (we thought we had found the answer in an article about a 'rogue star', but we can no long find the article or any mention of rogue stars)An example of a rogue star is Eta Carinae. This NASA web page offers information, links and a picture of this star.
January 30, 2008Sam ( U.S.A)what myths r there for the Little Dipper?Ursa Minor, also called the Little Dipper, is a circumpolar constellation. This means it never sets in the northern sky. The true figure represented by the stars is the Little Bear. Its counterpart is Ursa Major, or the Great Bear. There are several mythological stories behind these famous constellations. In Greek myth, Zeus was having an affair with the lovely Callisto. When his wife, Hera, found out she changed Callisto into a bear. Zeus put the bear in the sky along with the Little Bear, which is Callisto's son, Arcas. In other myths, the constellation is not a bear at all, but is in fact a dog. More information in our web page Ursa Minor (Little Bear).
January 15, 2008Regum (swindon/country)i am from west england and i would like to know which group of stars can be seen at autumn?You can see the main constellations observed from the North Hemisphere during each season in our web page Northern Constellations.
December 26, 2007Ashley (GA, Macon)what are stars mainly made out of? what fuel does it brun?The Sun, considered an average star, is mainly made of Hydrogen and Helium (70% Hydrogen, 28% Helium, 2% other gases).
December 26, 2007Lizzy (Canada / Vancouver)How do stars twinckle and shine?The movement of air in the atmosphere of Earth causes the starlight to bent as it travels from the star through the atmosphere to us. Some of the light reaches us directly and some gets bent, and to our eyes, this makes the star seem to twinkle.
December 26, 2007christopher (philippines)what is the smallest star?The smallest known star is OGLE-TR-122b. This article offers more information about this star.
December 19, 2007Jenna(Maryland, United States)How far away is the Andromeda Galaxy from the Milky Way?The Andromeda galaxy is about 2.9 million light years away from us. 1 light year = 9 460 528 400 000 kilometers.
December 17, 2007Yan (Malta)Since the Sun is a Star, is it true that all stars are suns?Yes, the Sun is just an average star. There bigger stars, and smaller stars. Visit our page Stars for more information.
December 10, 2007Matthew (GA, USA)How far is Perseus from earth?The brightest star of Perseus is á Per (Mirfak). Mirfak is at a distance of around 590 light-years from our system.
October 16, 2007veena (india)why the 'neutron star' has only 'neutron particle'?That statement is not exactly true. The matter at the surface of a neutron star is composed of ordinary atomic nuclei as well as electrons. As we proceed inward, we will encounter nuclei with ever increasing numbers of neutrons; such nuclei would quickly decay on Earth, but are kept stable by tremendous pressures.
October 16, 2007Conrad I would like to have a map of the Northern sky of constellations,ex.big dipper and other stars.Our web page Constellations offers a wealth of information, including some celestial maps.
September 25, 2007sara ( uk)is it true that when you look at stars your seeing them as much as a billion years ago?In general, we are able to see the stars and other celestial bodies due to the light they emit. The speed of light, althoug a very high value (around 300 000 000 meter per second), is finite; and considering the distance to the stars, the light takes a certain amount of time to reach our planet. A couple of examples. The closest star to our system is Proxima Centauri, at a distance of 4.2 light years. This means that the ligth from Proxima Centauri takes 4.2 years to reach us. The Andromeda Galaxy, on the other hand, is approximately 2.5 megalight-years away, this is, light from this galaxy takes 2.5 million years to reach us!
September 17, 2007Rebekah (Victoria)How many constellations are there in the southern hemisphere?Our page Exploring the Southern Hemisphere Constellations list the constellations for each season of the year.
September 12, 2007William (Georgia)What are the four circumpolar constellations of North Carolina?Asuming a latitud of 350N, the circumpolar constellations are: Ursa Major, the Big Bear (includes the Big Dipper); Ursa Minor, the Little Bear; Cassiopeia, the Queen of Ethiopia; Cepheus, the King of Ethiopia; Draco, the Dragon.
July 26, 2007Gary (ohio)Is there a point at the north pole where there is no stars?No, with a clear sky (no clouds) the view of the star should be magnificent (due to the low light contamination). This map offers te stars and constellations visible from the North Pole.
July 21, 2007Ryan (Philippines)What is the life cycle of a star in H - R diagram?Stars spend most of their life in the main sequence (while burning hydrogen and helium). Once a star has stopped burning hydrogen in its core, it begins to expand, and moves off the main sequence towards the upper right (the giant region). The more massive stars sit on the hotter portion of the main sequence, live shorter lives than the less massive stars, and become larger giants. Less massive stars sit on the cooler portion of the main sequence, live much longer lives, and may never become giant stars at all. Adapted from Hertzsprung Russell Diagram and Stellar Evolution.
July 20, 2007Shannon (California)I'm a Scorpio, I was wondering if I can see the scorpion constellation from my house and when can I see it?Scorpius is a Northern Summer Constellation. If you live in the northern hemisphere of the Earth, Scorpius crawls across the southern sky, close to the horizon. But if you live in the southern hemisphere, it passes high in the sky. More information about this costellation in our web page Scorpius.
July 20, 2007siddharth (uttar pradesh/india)How can a new star form from an old dead star in which all the hydrogen has been converted into Carbon or any other heavy element through a Supernova Explosion?This explosion happens because the center, or core, of the star collapses in less than a second. The outer layers of the star are blown off in the explosion, leaving a contracting core of the star after the supernova. The shock waves and material that fly out from the supernova can cause the formation of new stars. There are many beautiful images of supernova remnants, the expanding shell of gas made up of the outer layers of the original star. For more information, visit our web page Exploding Stars.
July 19, 2007radhika (india)can you please give me an information about zodiacal consetellationConstellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. More information in our web page Constellations and the links therein.
July 17, 2007ian (New York/United States of America)what is th brightness of a star as seen from Earth?The apparent magnitude of a star is a measure of its apparent brightness. The brightest stars that can be seen by the naked-eye are defined as “first magnitude”. Slightly fainter stars are called "second magnitude". This scale continues down to “sixth magnitude”, that are he faintest stars we can see (naked-eye) in very good conditions (no light pollution, no Moon). Extracted from Astrometry.
July 16, 2007roxann (ms.)how far is a star whose apparent magnitude is 12.7 and absolute magitude is 2.7"Absolute" (M) and "apparent" (m) magnitudes are related by the expression: m = M - 5(log10 d - 1) where d is the distance. Using the provided values we obtained about 100 parsecs.
July 13, 2007sherianne (singapore)Are there such things twin starsMost stars are members of multiple-star systems. Some stars are members of close binary systems where material from one star swirls around the other in an accretion disk. More information at NASA.
July 11, 2007daniela (texas)who could you look for in the summer sky?This webpage shows the constellation that can be seen in the summer sky. Also look for Mars over the southern horizon and Venus, which shows up before dawn in the eastern sky.
July 10, 2007jim I'm really interested in knowing if Cygnus (The Swan/Northern Cross) can be seen from midwest U.S. and, if so, where.Yes, the Northern Cross can be seen from the northern hemisphere. This webpage will help you to locate it.
July 6, 2007Bianca (Texas)What are the names of the five main groups of stars?One way to group stars is: Supergiants, Bright giants, Normal giants, Sub giants, Main sequence, and Subdwarfs.
July 3, 2007sunitha (india)how does a star be born and die,do they reproduce?Visit NASA-Star Lifecycle for a detailed explanation of the lifecycle of stars.
July 2, 2007QooBlack how do stars reroduce?Visit NASA-Life Cycles of Stars for a detailed explanation of the cycle.
June 28, 2007hunter (florida)What are the main stars of cancer?The main stars in Cancer are Alpha, a; Beta b; Gamma g; Delta d; and Iota i.
June 28, 2007kayla ( illinois)how did the white dwRF GET ITS NAMEWe already know that medium mass stars, like our Sun, become red giants. But what happens after that? Our red giant Sun is still eating up helium and cranking out carbon. But when it's finished its helium, it isn't quite hot enough to be able to burn the carbon it created. What now? Since our Sun isn't hot enough to ignite the carbon it its core, it succumbs to gravity again. When the core of the star contracts, it causes a release of energy that makes the envelope of the star expand. Now the star has become an even bigger giant than before! Our Sun's radius has become larger than Earth's orbit! The Sun is not very stable at this point and loses mass. This continues until the star finally blows its outer layers off. The core of the star, however, remains intact, and becomses the white dwarf. Extracted from NASA/White Dwarfs.
May 23, 2007Lucy (Vic)In the foot of the Aquarius constellation, can you please name the star?It depends what do you mean by "foot". If you are refering to the lower part of the constellation, then it is 88 Aquarii. If you want to know the starts at the feet of the "water bearer", then they are Epsilon Aquarii (right foot) and Iota Aquarii (left foot).
May 10, 2007Jerky (Indonesia)What is the little dipperUrsa Minor, also called the Little Dipper, is a circumpolar constellation. This means it never sets in the northern sky. The true figure represented by the stars is the Little Bear. Its counterpart is Ursa Major, or the Great Bear. More information in our web page Ursa Minor.
May 10, 2007Ally (Idaho, United States)WHat are the main stars that are in the constellation Andromeda?Some of th notable stars in Andromeda are Alpha Andromedae (Alpheratz or Sirrah), Beta Andromedae (Mirach), Gamma Andromedae, Pi Andromedae, 56 Andromedae, R Andromedae, RX Andromedae, and Groombridge 34.
May 10, 2007victoria (florida)what ia the whole background of the constellation columba?Columba is a small constellation just south of Canis Major and Lepus; it was cut out of the constellation Canis Major by Augustin Royer, in 1679. Before being designated as a full constellation, Columba Noachi was already to be seen as an asterism in Bayers Uranometria of 1603. Adapted from Wiki/Columba.
May 5, 2007Brian (British Columbia)Why a cooler star could actually appear brighter than a hotter star?How bright a star looks when viewed from Earth depends on two factors: (1) the actual brightness of the star -- that is, the amount of light energy the star emits (sends out) -- and (2) the distance from Earth to the star. A nearby star that is actually dim can appear brighter than a distant star that is really extremely brilliant. For example, Alpha Centauri A seems to be slightly brighter than a star known as Rigel. But Alpha Centauri A emits only 1/100,000 as much light energy as Rigel. Alpha Centauri A seems brighter because it is only 1/325 as far from Earth as Rigel is -- 4.4 light-years for Alpha Centauri A, 1,400 light-years for Rigel. Adapted from NASA - Star.
May 5, 2007Josh if Earth had no axis tilt, where would Crux be: closer to the celestial North pole or farther?For summer solstice conditions Crux would be closer to the equator, while for winter solstice would be farther.
April 19, 2007Faunce ( united states)what are the stars in hydraA complete list of the stars in Hydra can be found here.
April 19, 2007Emily (PA)What does the name corona borealis mean?Corona Borealis is a small northern constellation whose main stars form a semicircular arc. It has been known for a long time: Ptolemy included Corona Borealis as one of the 48 constellations listed by him.
April 13, 2007bella (va)I would like to know ALL of the names of the constellations, can you please tell me? I need to do the reserch about three of them. Thank youTo list all of the constellations here would take too long and too much space, but you can visit the web page NASA-Constellations for a comprehensive list.
April 7, 2007sophia (New Zealand)how old is the contellation aquarius?Aquarius has been known since long ago. In Greek myth, Aquarius was Ganymede, the young boy kidnapped by Zeus. Zeus sent his eagle, Aquila, to snatch Ganymede out of the fields where the boy was watching over his sheep. Ganymede would become the cupbearer for the Olympian gods. The constellation, Crater, is often thought to be Ganymede's cup. The Sumerians also believed that Aquarius brought on a sort of global flood. Also, many of the stars that make up Aquarius have names that refer to good luck. This is most likely due to the time of year when the Sun would rise in Aquarius. It happened to be at the same time when the rainy season began in the Middle East. For more information about this constellation visit our web page Aquarius.
April 7, 2007stephen (ca. usa)whatis the size of the southern crossAs with any other constellation, the size and proposrtions of the Southern Cross depend of the season and location of the observer.
March 31, 2007Davit (california)how do earh's rotation revolution affect the way we see stars?There are two important movements that affect the Earth: the rotation of the Earth around an invisible axis (one full rotation is completed in 24 hours), and its revolution around the Sun (one full revolution takes 365 ¼ days.) The first motion is responsible for days and nights, and the slow changes of the night sky.
March 27, 2007Laura (Colorado, USA)what machines or materials do you use to figure out the distance from different objects in space to Earth?There are currently no direct method to measure the distance to from Earth to stars and other objects very far away. Astronomers use the method of triangulation or parallax to obtain the distances to stars. This method is based on the known diameter of Earth's orbit (about 300 million kilometers). If we have two, six month apart, values of the viewing angle for a given star, it is relatively easy to obtain the distance with a little trigonometry. This technique works for stars within about 400 light years of our planet.
March 26, 2007amber (florida,usa)What is the total number of stars in the lyra constellation?The five most brilliant stars in Lyra are; Vega, Gamma Lyrae, Beta Lyrae, R Lyrae, and Delta2 Lyrae. For a complete list of stars in Lyra constellations, visit Wiki/Lyra.
March 21, 2007Vanamali (Karnataka, India)Sir,
Those stars with mass less than or eaqual to that of our sun, after the MAIN SEQUENCE stage enter the RED GAINT phase. What will be the fate of such stars afterr the RED GAINT phase?
A star with a mass similar to that of our Sun and in the last phase of its life is a red giant. Hydrogen fusion reactions have become less efficient in the core region, and the fusion reactions now occur in a shell surrounding the core. The outer layers then cool to about 3000 K and becomes a red star of a huge size. After a few more millions of years, the star evolves into a white dwarf-planetary nebula system.
February 28, 2007William (California United States)Please do in less than 4 days.what is a speical feature found on the consellation ScorpiusScorpius is a large constellation located in the southern hemisphere near the center of the Milky Way. Scorpius contains many bright stars and, due to its location on the Milky Way, also contains many deep sky objects such as the open clusters Messier 6 and Messier 7.
February 28, 2007Harry (Victoria)How big are galaxies?Using our Milky Way as an example: most of the stars in our galaxy are in a disk that is about 100 000 light years across in diameter and 3 000 light years thick. But keep in mind that most of the dozens of galaxies in our Local Group are at least ten times smaller in diameter.
February 28, 2007tim (wisconsin, u.s.)what are constellations, how are they made and what are there purposeConstellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture.
February 28, 2007sean (Iowa)What are constellations for?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture.
February 28, 2007dakota (IL)what is a star constellation?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture.
February 28, 2007jan (loundon)what are the 12 contellationsI believe you are asking about the constellations that are part of the Zodiac. They are: Aquarius, Pisces, Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, and Capricorn.
February 28, 2007Ruby (UAE)Why is it that the HD93129A, cannot be seen just like the Sun?While HD93129A is 120 times our Sun mass, and has a luminosity between 2 500 000 and 5 500 000 solar luminosities; it is also about 10,000-11,000 light years (1 light year = 9 460 730 472 580.8 km) distant. In comparison, our Sun is only around 150 000 000 km from our planet.
February 24, 2007BRITTANY (NC/USA)DO YOU HAVE A PICTURE OF ORION?Please, visit our web page Images of Orion.
February 20, 2007Brent (Canada)What is an old, cold star called?A white dwarf is an astronomical object produced when a star of low or medium mass dies.
February 13, 2007Jeremy (ohio,us)Is Aquarius close to the big dipper?No, thay are in different sectors of the sky. Ursa Major (The Big Dipper) is a Northern Circumpolar constellation, Aquarius is a Northern Autumn constellation.
February 13, 2007Allison ( New York)When were constellations first studied?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many ancient societies saw patterns among the stars with gods and goddesses or stories from their culture. More related information in our web page Constellations.
February 12, 2007kalyan (india)stars twinkle, from wherever we see them,i am sure ! why ?Stars twinkle (when seen from the Earth's surface) because we are viewing them through thick layers of moving air in the Earth's atmosphere. The scientific name for this phenomenon is stellar scintillation.
January 23, 2007Vipul (India)How is the end of a white dwarf?A white dwarf core has no further source of energy, and will gradually cool down and becomes extremely dense. The maximum mass of a white dwarf, beyond which degeneracy pressure can no longer support it, is about 1.4 solar masses. A white dwarf which approaches this limit (typically by mass transfer from a companion star), may explode via a process known as carbon detonation.
More information can be found at Wikipedia, and at our web page White Dwarfs.
January 23, 2007kelsey (USA)What is the and and size relative to our sun of the star Kuma, from the constellation Draco?Kuma, also known by its Greek letter name Nu Draconis, is a double star (Nu-1 and Nu-2) . Both stars shine with about 9 times the luminosity of the Sun and have masses 1.7 times the mass of our Sun.
January 23, 2007vanessa (Illinois)what season does cepheus the constellation come out ?In the north hemisphere, depending of your latitude, Cepheus is one of the circumpolar constellations (permanently visible).
January 23, 2007Nathan (Canada)Why do stars form constellations?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. Fore more information visit our web page Constellations.
January 21, 2007kierra (IN)what are the stars names in the scorpius?More than any other constellation, Scorpius resembles its given name. If you live in the northern hemisphere of the Earth, Scorpius crawls across the southern sky, close to the horizon. But if you live in the southern hemisphere, it passes high in the sky. The bright star Antares marks the heart of the arachnid, and its long curving tail trails to the south. Scorpius contains many bright stars, including Antares, Graffias, Dschubba, Sargas, Shaula, Jabbah, Grafias, Alniyat, and Lesath. For more information, please visit our web page Scorpius.
January 16, 2007devon (kansas)what is cetusThe constellation Cetus represents the Sea Monster. It is one of the largest constellations known. In classical civilizations, the figure was the giant sea monster that almost ate Andromeda. More information on this constellation can be found in our web page ,Cetus.
January 16, 2007Emerson ( Australia)What are the names of the two stars that point to the Southern Cross?
Thank you.
Alpha Centauri and Beta Centauri are used to localize the Southern Cross (the Crux). If a line is drawn between them,is easy to find the top of the Crux. The two stars are often referred to as the "Pointer Stars" or "White Pointers".
January 5, 2007maria (usa)I need to know 5 facts about the constellation Aquarius pleaseAquarius is a member of the Zodiac, a group of constellations that the Sun travels through each year. It is best viewed in the fall in the southern sky, although much of the northern hemisphere can see the Waterbearer in the spring. Aquarius is one of the oldest constellations in the sky. Fore more information about this topic, please visit our web page Aquarius.
January 5, 2007summer (denison)how did we find out that was other plantesThe motion of the planets in the sky is quite different from the stars. For example, stars move with a very low pace, while planets move faster. Planets also have what is called Retrograde Motion, a reversed motion through the stars relative to average yearly motion.
January 3, 2007bob (NZ)I am doing a school topic on an aspect of space.Can you please tell me some info on scorpius?Some constellations do not really look like their names. It takes a lot of imagination to picture the stars of Pegasus as a winged horse, for example. But Scorpius really looks like a scorpion! It has a long, curving tail, and snapping claws, just like the real arachnid. The bright star Antares marks the heart of the scorpion. For more information about this constellation, please visit our web page Scorpius.
December 20, 2006Yoomin (Ontario, Canada)I'm doing a project on the stars.
What is a neutron star?
Neutron Stars are the end point of a massive star's life. When a really massive star runs out of nuclear fuel in its core the core begins to collapse under gravity. When the core collapses the entire star collapses. The surface of the star falls down unti l it hits the now incredibly dense core. It then bounces off the core and blows apart in a supernova. All that remains is the collapsed core, a Neutron Star or sometimes a Black Ho le, if the star was really massive. More information can be foun at our web page Neutron Stars.
December 14, 2006rija (united states)i need information on the constellation canis major, what is canis major?The constellation Canis Major is known as the Great Dog. In Greek myth, it is said that this constellation, along with Canis Minor, are Orion's hunting dogs. Canis Major was one of the most important constellations in ancient times because the brightest star in the sky is part of it. For more information about this constellation, please visit our web page Canis Major
December 13, 2006Karina (New Mexico)How mant myths does Hydra have?For a description of Hydra myths, visit our page The Lernaean Hydra.
December 9, 2006kenedi (scotland)how did the big dipper help people when they were travelling?Ursa Major is full of unique celestial objects. Two of the stars, Dubhe and Merak, are pointer stars. If you are looking at the Big Dipper, the outer edge stars that make up the "bowl" of the dipper are the two stars, with Merak being the one on top. Connect a line between the two, and extend it north a distance about five times the distance between them. It will connect with the North Star, Polaris. More information can be found at our web page Ursa Major.
December 9, 2006Allen How are constillations made?Constellations are formed of bright stars which appear close to each other on the sky, but are really far apart in space. The shapes you see all depend on your point of view. Many societies saw patterns among the stars with gods and goddesses or stories from their culture. Fore more information visit our web page Constellations
December 9, 2006kiarrawhat is the sign for myths piscesThe constellation Pisces is known as the fish. Almost every ancient civilization saw this figure. For more information about this topic, please visit our webpage Pisces.
November 30, 2006paris (Virginia,Unitedstates)What is a supernova?A supernova is a stellar explosion which produces an extremely bright object made of plasma that declines to invisibility over weeks or months. More information can be found in our page Supernova.
November 20, 2006Hero (Manila, Philippines)what are some common examples of constellation ?Common examples of constellations are: Cassiopeia, Ursa Major, Ursa Minor, Cancer.
For a comprehensive list of constellations and interesting facts and myths related to them, visit this page.
September 24, 2004Jessica ( MS, USA)What is the exact myth of the constellation, Aquarius.Aquarius is one of the constellations of the Zodiac. He is known as the waterbearer.
September 8, 2004Chelsea(Indiana)What is Pegasus?Pegasus is one of the constellations you can see in the Northern hemisphere. It is actually in the sky right now (just below the summer triangle) and will remain there through the Fall. Pegasus represents the white, winged horse of Greek mythology.
April 4, 2003Natassja (Australia)What is the difference between a planet & a star?Because stars are so large (massive), the pressure and temperature at the center of a star is very high. So high, in fact, that it causes a nuclear reaction called "nuclear fusion". Fusion reactions give off lots of energy, which is what causes a star to shine. Planets simply do not have enough mass to squeeze their centers to the point where nuclear fusion starts.
August 31, 2002Brian ( Ohio, USA)In the nuclear fusion process that goes on in a star, I learned that the abundant element of Hydrogen was used for the fusion into Helium. Hydrogen, an atom of 1 proton, into Helium, an atom of 2 protons and 2 neutrons. How do the neutrons form?Yes, that is puzzling, isn't it? However, there is a type of hydrogen, called deuterium, which has a neutron and is involved in nuclear fusion reactions on the Sun. Two deuterium hydrogen molecules (which each have one proton and one neutron) are fused together making one helium atom (which has two protons and two neutrons)!

January 7, 2002Sondra (Connecticut, USA)I need help finding information for a report on the north star.. any info is greatly welcomed!The north star, also referred to as Polaris or the Pole Star, is the brightest star in Ursa Minor. Make sure to try these links for more information!
August 14, 2001Bernadette (New Jersey, USA)How many total stars are there in the Milky Way?The estimate that scientists have come up with is around 200 billion stars. For more information, see the following page. It has the answers to several recently asked questions on the Milky Way.
August 14, 2001Ahmet (New Jersey, USA)What is the earliest reference to the Southern Cross?The Southern Cross constellation was known thousands of years ago to astronomers, but hasn't been visible to those in the northern latitudes (25 N and above) since about the time of Christ. The constellation was rediscovered in the sixteenth century by European navigators, who used it as a marker in the southern skies when exploring.
August 6, 2001Mohammed (NWFP, Pakistan)How can I get the star map for my location or which would be the nearest match that I can see?There are a lot of web sites and free software packages that will give you a star map for a given location. Try this page. All you need to do is give your latitude and longitude and it will give you a customized map.
July 31, 2001Mick (Florida, USA)Suppose Star X is 1000 light years away and exploded today...which means we won't see the supernova until 3001. But we keep seeing this Star X through our telescope for the next thousand years, is that illusion?It's not really an illusion, because we're seeing the real star. The important thing to remember is that we're always seeing light that stars emitted long ago, so we would continue to see the light it emitted before it exploded, until the light from the explosion reached us in 3001 and we could see that it exploded.
June 20, 2001Phyllis (USA)The north star is also known by what name?Polaris is the famous north star!
June 15, 2001Joanna (Victoria, Australia)What is the life cycle of stars?Here's a tour on the life cycle of stars.
May 14, 2001M Eddy (Florida, USA)How do stars differ?This tour called A Peek into the Lives of Stars should help. It explains the different types of stars and how an individual star can vary over its lifetime.
April 24, 2001Janetta (Montana, USA)What exactly is an HR diagram and what is it for?The Hertzsprung-Russel diagram allows you to easily group stars by magnitude, spectral class, luminosity and temperature. An interactive version is available on-line.
March 27, 2001Agnes ( Hungary)What should I know about 'Cassiopeia'? (Location,facts,etc)This page should help.
February 19, 2001Michele (Canada)In the night sky, one can consistently see one 'star' that is much brighter than another. I've been told it's Venus and I've been told it's a space station. Any thoughts?Venus has been shining very brightly in he night sky. But, if the 'star' you see slowly moves across the sky (like other satellites do) as you watch it, it very well may be the ISS moving across the sky. There's one way to tell. Check out these two links. They will tell you when and where to look for the space station. (1), (2). Finally, this link will help you find where Venus is in the sky.
November 10, 2000Anne Hi. I was wondering if you could help me with this science question: double stars in which one star moves direcly in front of the other star. And it looks like this scrambled up : spingielc asibinre Can you help me?I love puzzles! Looks like eclipsing binaries to me!
October 30, 2000Chris (Illinois, USA)What are the nearest 11 star systems?This page shows the closest stars to Earth and the brightest stars as seen from Earth.
October 15, 2000Charles What is the absolute brightness of these stars: Altair and Acrux?Altair's absolute magnitude is 2.2 while its apparent magnitude is 0.77. Acrux's absolute magnitude is -3.5 while its apparent magnitude is 0.9.
October 12, 2000Ami (Texas, USA)What are the names of the two stars that make up the heads of Gemini?Castor and Pollux make up the heads of the constellation Gemini.
September 26, 2000William (Britain)One constellation is shaped like a 'W'. What is its name?Cassiopeia is its name!
August 4, 2000Sherry (Australia)I would like to know who first discovered constellations and when they discovered constellations.

Ancient civilizations saw different objects in the night sky. Constellations weren't discovered, they were imagined! The Babylonians, Greeks, Romans and other civilizations told us what they saw. We see those stars to day and therefore see the constellations!

June 13, 2000Fernando (Spain )Why do planets and stars shine in the night sky?

Planets shine because the light from the Sun is reflected off the surface. This is also why we see the Moon at night.

Stars, on the other hand, create their own light, just like the Sun. If you want to know how stars create light, look here!

June 8, 2000Rita (New York, USA )Which star is the closest to the earth & how close is it?

Of course, the Sun is the closest star to Earth. However, I'm assuming you want to know the next closest star.

Alpha Centauri is the next closest star. It actually consists of three stars, the closest one being Alpha Centauri C, with a distance of 4.2 light years.

May 15, 2000Godfrey (Utah, USA)Based on the distance of the stars and the speed of light. When I look up at the stars tonight am I seeing what is there now or what was?

When you look up into the sky, you are actually looking into the past. You see, it sometimes takes many years for light from a distant star to reach us. That light was given off many years ago, but we are just now looking at it.

It's a lot like going to a ball park. When the batter hits the ball, it takes a few seconds for the crack of the bat to reach the outfield. So, it's like you are hearing the past!

April 20, 2000Annalies (New York, USA)how far is orion from earth in light years

The stars that make up constellations are not next to each other. In reality, some stars are a lot closer to us than others. Because they are so far away, they appear to be closer to each other!

April 18, 2000Valerie (Wisconsin, USA)What is some important information about the constellation Horologium? (I would like to know about its star Alpha, such as absolute magnitude, relative temperature, where it could be found on the Hertzsprung-Russell diagram, how old it is, and what stage it is in.)Horologium is also known as The Clock. It is a southern constellation and its stars have no well-known names. The star, Alpha, has an apparent magnitude of 3.9 and sits 190 light years away. Alpha is an orange giant.
March 22, 2000Brittany What is a constellation?Constellations are patterns of bright stars which appear close to each other in the night sky.
February 15, 2000Brandon (Illinois, USA)can you send us a picture of Alnitak in Orions beltHere's a picture of Alnitak, or Zeta Orionis, part of Orion's Belt. Alnitak is the brightest star in the picture.
January 25, 2000Harriet (United Kingdom)What do you call the first star in any constellation?The first star in a constellation is usually known as "Alpha", as in "Alpha Centauri". Sequential stars are known as beta, gamma, epsilon, etc.
January 24, 2000Jade (Colorado, USA)How many known consttelations are there?Officially as of 1930 there are 88 constellations which cover the entire sky. There are many objects in the sky however which are recognized but not official constellations. These objects are known as asterisms. For example, the constellation Ursa Major includes the stars which form the Big Dipper.
November 16, 1999Julie (Florida, USA)Who discovered the constellation Pegasus? and when was it discovered?

No one knows for sure who actually discovered the large constellation, Pegasus. We know that the ancient Greeks and Romans named the constellation Pegasus, but some scientists say that even those living in ancient Mesopotamia probably saw the figure of a horse in the sky.

October 27, 1999-- (New York, USA)Which constellation is also known as 'The Plow'?This would be the constellation we know as the Big Dipper, called the Plough by the British.
October 15, 1999April (Colorado, USA)Where did they come up with the seven stars of pleides? or is it the seven sisters of pleides?The story of the Pleiades started many years ago. Many different cultures had a story explaining this famous group of stars.
You can read about the Greek story of the seven sisters here . Or maybe you would like to know more about the Hindu myth .
September 28, 1999Anna Kathleen (Georgia, USA)What are the light year distances of the stars of andromeda?This table has a list of all the stars in Andromeda and their distances from Earth.
September 21, 1999Melecio ( California, USA)I was told that you can approximate the distance of near stars by using some kind of triangular formula, what is the formula?There is a very simple formula you can use to find the distance to stars. The distance is equal to one divided by the parallax, or d=1/p, where p is the parallax.

This equation is based on geometry. If you look at an object close to you as you walk by, it appears to move! For example, look at a tree close by while looking at the scenery behind it. As you move, the tree seems to move relative to the background.

This is also used to measure distances to stars. As the Earth moves around the Sun, the star you are measuring appears to move relative to the stars behind it. To find the distance, first look up the parallax in a book. The parallax is the angle between the Sun and Earth, from the star's point of view.

Divide 1 by the parallax, and you will have the distance in parsecs! (One parsec is 3.26 light years, or 100,000,000,000,000 kilometers!)

September 16, 1999Michel (France)what is the distance between the earth and the neariest star ? what is the name of this star ?Alpha Centauri is the star nearest to the Earth. It is 4.35 lightyears from the Sun.
June 16, 1999Sergio (Oregon)How many galaxies are in the universe?
How many stars are in each galaxy?
There are over 100 billion galaxies in the visible universe. The number of stars in each galaxy varies widely, but each galaxy probably has a couple billion stars on average. Talk about alot of stars!
June 11, 1999Morgan (Washington)What is a binary star, and how common is it?A binary star is simply two stars revolving around each other. About half of the visible stars in the night sky are actually binary star systems.
June 3, 1999Katheryn (UK)I understand how Cepheid variables work, but what causes them to pulsate in the first place, and why do they not reach equilibrium?When a Cepheid variable is compressed by gravity, photons are trapped inside it, causing the star to become opaque. This compression increases the pressure and temperature of the gas. The gas then expands and becomes transparent. Then the gas cools and the pressure drops as photons are able to escape. As the pressure drops, the star is again compressed by gravity.
May 7, 1999Paul (New York, USA)Are all the stars that can be seen with the naked eye part of the milky way galaxy? Are any stars not part of any galaxy? Are Deep Space non galaxy objects (ie. ring neb. dumbell neb. Orion Neb. double stars etc. messier and ngc objects)part of the milky way?All the stars we see with our eyes are part of the Nebula that we see in books like the Orion Nebula are all in the Milky Way galaxy as well. There are many in other galaxies too, but we can't get take such beautiful pictures of them because they are too far away!
April 7, 1999Mike (California, USA)Are there stars between the galexies?There are, a few. All stars are form inside a group of matter such as a galaxy, but when galaxies collide, sometimes stars are ejected into intergalactic space.
April 1, 1999Adam (Pennsylvania, USA)What are Quark Stars? (there was a question on Jeopardy, pertaining to a superdense star who's name related to a subatomic particle, the right answer was neutron star, but the fellow answered quark star and they said that was correct as well)Quark stars are neutron stars which are on their way to becoming black holes. When neutron stars collapse, their atoms break apart into their subatomic particles, quarks. These stars are very unstable, right on the edge of becoming a black hole .
March 29, 1999Eileen (Illinois, USA)What is 'Eagle Nebula'?The Eagle Nebula is a young star cluster surrounded by a cloud of gas produced by the star formation. Here is a picture of it!
March 22, 1999Greg (USA)What causes the apparent movement of constellations over the course of a night? over the course of several months? What are circumpolar constellations?The effect of motion of the stars is caused by the motion of the Earth. This is called "apparent motion." This page will help.

Circumpolar consellations are consellations which never set, because of the way the Earth rotates.

October 16, 1998Erin and Lindsay (Virginia, USA)Where do you come up with the names of stars? Why are some just names and other numbers?
Where do come up with the names for stars and galaxys?
Most of the brightest stars in the sky have proper names which have been used since ancient times, for example Vega, Polaris, Rigel. However, it is obviously impossible to name every star visible to the naked eye. So, an astronomer named Bayer came up with a system for designating stars in the constellations. Each star was assigned a letter of the Greek alphabet, beginning with Alpha, usually assigned to the brightest star, and so on. Thus, the brightest star in Lyra is "Alpha Lyrae." Remaining, fainter stars are given numbers, usually listed in some kind of catalog. Star clusters, nebulae, and galaxies are usually listed in catalogs and given numbers and a category designation. The title for these objects depends on which catalog classificatio n is being used.
October 15, 1998Danielle (Rhode Island, USA)What are the five main groups of stars?One grouping of stars classifies them as Supergiants, Bright giants, Normal giants, Sub giants, Main sequence, and Subdwarfs.
September 14, 1998Sarah (Wisconsin, USA)What are the stages of a star...?We have an excellent tour on our site that deals with just that question!
May 27, 1998Kaelyn (Oklahoma, USA) What is the name of the largest known star? Do black holes have names?The most massive star known is R136a1, a star 155 times as massive as our Sun. It is one of many extremely massive stars in a very young "super cluster", R136, in the 30 Doradus region of the Large Magellanic C loud.

Black holes don't have names like the bright stars in our sky, such as Betelgeuse. We cannot detect black holes directly, but we can sometimes detect x-ray emission from the material surrounding them. This related x-ray source may be named. Cygnus X-1, for example, is the 1st x-ray source detected in Cygnus, and is probably a disk of gas and dust spiraling into a black hole.

May 27, 1998Andrew (California, USA) On a clear night, I can see thousand of stars in the sky; However, why don't I see any stars in space from any videos shot by space shuttle while it is in its orbit?You're right! You should be able to see about 5000 stars over the course of a clear night from the Earth. From the space shuttle (or anywhere above the Earth's atmosphere), these stars shine even more clearly! The videos you saw were probably taken during the day, when the Sun was shining on the shuttle and so blocking out the light of the other stars...read Andy Thomas's last letter home from Mir to get a better feel of night and day ou t in space.
May 12, 1998Roxana (Sweden) What is a supernova?When really massive stars die they often blow up in a huge explosion called a supernova.
May 12, 1998Azael (Texas, U.S.A.) How many stars are there in the universe?In our visible universe alone, there are 100 billion galaxies. Each galaxy probably has a few billion stars in it. So that's at least 10^20 stars or far more hamburgers than even McDonald's has served!

An easier number to grasp is the number of stars we can see on a clear night...with really good vision (and if you stayed up all night!), you'd be able to see about 5500 stars.

April 24, 1998J.B. I keep coming across the term 'when a star dies'. What does this mean, and what causes a star's death?As a star grows older, eventually it has burned all its hydrogen. It then moves on to heavier elements, fusing them to create energy. Eventually it has a core of iron, which the star again tries to fuse to create energy. This leads to a massive exp losion called a supernova. The stellar matter again collapses, and can form either a white dwarf, a neutron star, or a black hole, depending on the star's origional mass. This entire process is the death of a star.
April 7, 1998Jason (Rhode Island, U.S.A.) How is a star formed?For a description of how stars form, look here.
March 24, 1998Zachary (New York, USA) What can you tell me about blue stars? I would like to know the size, compared to other stars; what happens after they burn out; what do they turn into next?Blue stars are very very hot, about 10,000-25,000 degrees Celcius. They are be very massive, and to have relatively short life spans--only 10 million years or so. Blue stars, since they are so huge, tend to go supernova.
March 5, 1998Michelle (Michigan, USA) I have heard that there is a place on earth where Polaris is concealed. Is there a place where it cannot be seen?Yes, since Polaris is located nearly directly above the North Pole, no one in the Southern Hemisphere can see it.
March 5, 1998Anne (Philippines) Do we see different sets of star after six months wherein our night time is at the opposite side of the sun?Yes, we do. Relatively speaking, the Earth is in the same place with respect to the entire field of stars, because the orbit of the Earth is a very small distance compared to the distance to the stars, but we're essentially facing a different way. It would be the same if you were sitting in your chair in the office and swiveled around the other way. The room hasn't changed but you're now looking at a different view.
February 27, 1998Matthew (Texas, USA) How far from the earth and each other are the stars of the constellation Cancer?Cancer has two Messier objects--
M44 (NGC2632)--520-590 light years away. "The Beehive"
M67 (NGC2682)--2500 light years away. Located 2 degrees W of alpha Cancri and 9 degrees S of M44
Cancer also has several small variable stars and some double stars. To see their distances and locations, click here.
February 19, 1998Jessica (Texas, USA) What is a white dwarf star?When stars like our own Sun die they will become white dwarfs. As a star like our Sun is running out of fuel in its core it begins to bloat into a red giant. After a few million years the outer layers of the red giant will begin to blow off and form a planetary nebula. Leaving behind only the dead core of the star made of mostly carbon and oxygen. This is the White Dwarf.

A typical white dwarf is smaller than Earth. It is also very dense and hot. A spoonful of white dwarf material on Earth would weigh as much as a car. Strange, isn't it?

February 10, 1998Stan (Michigan, USA)When they list the magnitude of a star, why are negative numbers brighter than positive numbers? Sun -26, Polaris +2. Go figure!!The magnitude system which describes the brightness of stars was first established over 2000 years ago by a Greek astronomer named Hipparchus. Hipparchus observed nearly 1000 stars, not with a telescope, but with only his eyes. The brightest stars he called "first magnitude" and the faintest stars he called "sixth ma gnitude". Because of the way our eyes work, it turns out that 5 magnitudes is equivalent to a factor of 100 in brightness. This same system, which is still used by astronomers today, now extends to even fainter stars such as those which can be seen with binoculars (about tenth magnitude) and telescopes (about 20th magnitude). The Hubble Space Telescope can see down to nearly 30th magnitude - that's about ten million times fainter than you can see with your eyes! The system has also been extended to neg ative numbers to include the brightest objects in our sky, like the star Sirius, the planet Venus, and even the Sun and the Moon.
February 10, 1998Teresa (Idaho, USA)What is an eclipsing binary?A binary is a double star system; two stars orbiting each other. From the Earth, some binary stars appear as one star, either because they are close together, or because they are far away. If we are seeing the system edge-on (looking from the side of the star system rather than from above), then at some time, the stars will pass in front of each other, eclipsing each other. This causes the brightess of the one "star" (which is actually two stars) to change in a very specific way which astronomers can recognize. So even though the stars appear as one star, astronomers can tell from the way that the brightness changes that there are actually two stars - an eclipsing binary.
January 29, 1998David (Iowa, USA)Can the mass of stars change? If so at what rate does the stars mass dissipate?Stars lose mass as they give off energy. This occurs when protons and neutrons fuse togther, emitting radiation. The rate at which the mass changes depends on the size and age of the star. Our Sun loses 7 million tons of material every second. How ever, the total lost so far is only .01 percent of its mass since it began shining. So, there is no need to worry about the Sun wasting away to nothing for a very, very long time!
January 20, 1998Eric ( Virginia, USA)What is the geometric relationship between the Great Pyramids in Egypt and our universe?Apparently, some of the pyramids were laid out in a manner corresponding to constellations such as Orion's belt. Others seem to match stars important to particular Pharaohs or dynasties.
January 13, 1998Jessica (California, USA)What is the major cluster of Pegasus?Pegasus, the Winged Horse, (confusingly) flies upside down. If you find Pegasus (during the summer in the northern hemisphere), you'll notice it is made up by the 'Great Square of Pegasus'. The southwestern-most star is white Markab (literally meani ng 'the thing for riding on'). Its neighboring corners are yellow Sheat ('leg') and white Algenib ('flank'). In the northeastern corner of the square is a double star system (white and purplish) named Alpheratz.
January 13, 1998Andy (Michigan, USA)What is the apparent magnitude of the stars in the constellation Aquarius?Here's five Andy: Sadalmelik (alpha Aquarii) is V 2.96, Sadalsuud (beta Aquarii) is V 2.91, Sadachbia (gamma Aquarii) is V 3.84, Skat (delta Aquarii) is V 3.27, Al Bali (epsilon Aquarii) is V 3.77. The higher the number here, the fainter the star. (The apparent magnitudes measured in spectral ranges other than visible would appear quite different).

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