Shop Windows to the Universe

Earth Science Rocks! Select one of our four cool NESTA t-shirts from our online store, and express your love of Earth and space science!
Art and science combine to show an ancient view of the Sun and Earth. Look closely to see the Sun in the center. Four images of Earth surround the Sun. Each Earth represents the different seasons, spring, summer, autumn and winter. Original art by Andreas Cellarius (1596-1665).
Click on image for full size
(c)1995 Visual Language, All Rights Reserved

As the World Turns

In our time, scientists (and most people!) know that the constellations seem to move across the sky because the earth rotates on its axis. What, you may ask, does the turning of the earth have to do with the constellations' motion across the sky? The answer is that the earth moves in a way that makes it look as if the constellations are moving. It is a case of apparent motion. In the case of the earth and the constellations the earth rotates, with us on it, from west to east. The constellations appear to move from east to west, moving "backwards" from the real rotation of the earth. Actually, instead of saying the constellations rise we should say that the earth has rotated so that we can see different constellations. Then, as the earth continues to rotate the constellations apparently move across the sky. We now know that it is us, on earth, that have moved. As the night progresses constellations that are near or below the ecliptic "set" in the west, we know that the part of the earth we are standing on has turned so that the Earth is blocking our view of the stars that have "set".

Shop Windows to the Universe Science Store!

The Fall 2009 issue of The Earth Scientist, which includes articles on student research into building design for earthquakes and a classroom lab on the composition of the Earth’s ancient atmosphere, is available in our online store.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Science, Evolution, and Creationism

How did life evolve on Earth? The answer to this question can help us understand our past and prepare for our future. Although evolution provides credible and reliable answers, polls show that many people turn away from science, seeking other explanations with which they are more comfortable....more

Andromeda

Andromeda is a "V" shaped constellation best viewed in the fall if you live in the Northern Hemisphere. Andromeda lies close to the north pole, so only a few in the Southern Hemisphere can see this strangely...more

Aquarius

Aquarius 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...more

Cancer

Cancer, the Crab, is a member of the Zodiac, a group of constellations that the Sun travels through each year. Cancer is best seen during the month of March, but is visible from December through June....more

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...more

Capricornus

The constellation Capricornus represents the figure of either a goat or a sea-goat in the sky. Capricornus is also a member of the Zodiac, a special group of constellations that the Sun travels through...more

Cetus

The 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. King Cepheus...more

The Unchanging Sky

The unvarying aspect of the relationships of the stars' positions may have suggested to the ancients something that was analogous to their beliefs about the universe. It is not surprising that they chose...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