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This is a digital image of the scientific illustration known as, Scenographia Systematis Copernicani (the Copernican System) by Andreas Cellarius(1596-1665). Cellarius produced this illustration for his book, Harmonia Macrocosmica; posthumously published in 1660. Look closely to see a Sun-centered image with the Earth’s positions relative to the Sun at the beginning of each season.
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(c)1995 Visual Language, All Rights Reserved

The Changing Night Sky

If you look at the night sky at 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. As the Earth revolves about the Sun, the Sun appears to move through the constellations. Therefore, different constellations will be visible in our night sky at different times of the year. You can't see the stars if the Sun is near them! 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 there are 365 days per year and 360 degrees in a circle, like that of the Earth's orbit. The Sun appears to move about one degree in the sky per day as the Earth goes around it, which means the the shift in the stars and constellations we see each night must be about one degree.

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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.

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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

Andromeda is a "V" shaped constellation best viewed in Autumn if you live in the Northern Hemisphere. It was one of the earliest constellations to be recognized. Andromeda lies near the celestial north...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 autumn 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 spends half of the year in the sky. It first rises in December and is visible through...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. It is believed to be the oldest constellation known. Capricornus is also a member of the Zodiac, a special...more

Cetus

The constellation Cetus represents the Sea Monster. It is one of the largest constellations known. Even the ancient people of Mesopotamia recognized this large constellation. They believed the figure was...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