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This is a digital copy of an old drawing. It shows the Sun surrounded by four Earths. There are four Earths, one for each season. Original art by ndreas Cellarius (1596-1665).
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(c)1995 Visual Language, All Rights Reserved

The Changing Night Sky

If you look at the night sky different times of the year you see different constellations. This change is due to the motion of the Earth in its orbit around the Sun. Each day a few stars are visible in the east that were not visible the night before. If you were to measure how much the sky "shifted" from one day to the next you would discover that it "shifts" approximately one degree per day. This should not be surprising because, if you think about it there are 365 days per year and 360 degrees in a circle. Anyway, the sky doesn't shift, it is another case of apparent motion. The "shift" of the sky is really the motion of the earth around the sun.

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The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

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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

The fall constellation Andromeda is a Princess. She looks like a "V"! Andromeda is close to the north pole, so only a few people in the Southern Hemisphere can see it in the spring. Andromeda's parents...more

Aquarius

Aquarius is also known as the Waterbearer. There are several myths about this constellation. In Greek mythology, Aquarius was the young boy, Ganymede. Zeus sent Aquila to kidnap Ganymede. The boy became...more

Cancer

The constellation Cancer is a crab. Look for Cancer from December through June. It's hard to see Cancer because the stars are so dim. To find Cancer, first find Gemini and Leo. Cancer is right between...more

Canis Major

Canis Major is known as the Great Dog. In Greek myth, it is one of Orion's hunting dogs. Many cultures saw the shape of a dog in this constellation. Sirius is the brightest star in the sky. It is also...more

Capricornus

The constellation Capricornus is a goat. Many years ago, people thought this constellation was a gate to the Heavens. Souls would go through it after a person died. The Greeks thought it was a sea-goat....more

Cetus

The constellation Cetus is known as The Sea Monster! It is a very large constellation. The Greeks thought the figure was the monster that tried to eat Andromeda. Perseus saved Andromeda and married her....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 by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF