Hubble Space Telescope image of Sirius, the brightest star in the sky, and its tiny white dwarf companion.
Click on image for full size
NASA, ESA, H. Bond, M. Barstow

Sirius A - Brightest Star in the Sky

What's in a Name: Greek for "Scorcher". Also called the "Dog Star". Sirius was not visible in the night sky during the summer months, therefore the Greeks thought that Sirius added its heat to that of the sun, producing the warm summer months. The hottest days are still called "dog days".
Claim to Fame: Brightest star in the sky (apparent magnitude=-1.5). In a few billion years it should become a giant and then a white dwarf. Now the surface is enriched in metals. Believe Sirius B (its white dwarf companion) passed material to Sirius A during the process of becoming a white dwarf and caused the enrichment.
Type of Star: White Main Sequence Star (A1 V spectral Class)
How Far Away: 8.7 light years away (2.7 parsecs)
How Big: 1.8 times the Sun's diameter
How Bright: 23 times the Sun's luminosity (Mv=+1.4)
Where to View: In the constellation Canis Major (Star Map).
When to View: January through March

Last modified January 25, 2006 by Travis Metcalfe.

You might also be interested in:

Cool It! Game

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Magnitude - a measure of brightness

Astronomers use a special term to talk about the brightness of stars. The term is "magnitude". The magnitude scale was invented by the ancient Greeks around 150 B.C. The Greeks put the stars they could...more

Gamma Ray Bursts - The Most Powerful Objects in the Universe?

Satellites in the 1960's looked for a type of light called Gamma Rays. They found bursts of Gamma Rays coming from outer space! They can't hurt you. They are stopped by the Earth's atmosphere. We have...more

Galaxies - Star Cities

When we look up at the night sky, we notice that there are many stars in our sky. Stars must like to live together in star cities - galaxies. Our city of stars is called the Milky Way, and it is home to...more

Neutron Stars

Neutron Stars form when really big stars die. When such a star runs out of fuel its center begins to collapse under gravity. When the center collapses the entire star collapses. The surface of the star...more

Spiral Galaxies

Spiral galaxies may remind you of a pinwheel that blows in the breeze. Like a pinwheel, a spiral galaxy is rotating, and it has spiral arms. Through a telescope or binoculars,a spiral galaxy may look...more

White Dwarfs

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 center it grows into a red giant. This will happen to our sun in 5 Billion years. The...more

Algol

What's in a Name: Arabic for "head of the demon" Claim to Fame: Represents Medusa's eye in Perseus. A special variable star that "winks" every 3 days. Type of Star: Blue-white Main Sequence Star, and...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA