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The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.
This image shows different objects that rotate. Rotational period is the time it takes for that object to rotate just once.

Rotational Period

Rotational period is the term describing the length of time necessary for a space object to make one complete rotation. This time varies from planet to planet, and on Earth it is 1 day.

This length of time is not constant, and in fact the Earth’s rotational period is slowing (by 0.002 seconds every hundred years). This is because of the Moon’s influence on our rotation. Sometimes collisions are also thought to slow rotational periods, and this is how scientists explain Venus’ rotation. Venus has a retrograde (backwards) rotation, and it is very slow. In fact, it is so slow that it revolves around the Sun faster (by about 17 Earth days) than it spins around its own axis. This means that a Venus day is longer than a Venus year!

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Cool It! Game

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AU

AU stands for Astronomical Units. Distances in space are too large to measure in Earth standards like miles or kilometers. For distances too large to measue in AU, we use light years. A light year is the...more

The Spiral of the IMF

The solar wind is formed as the Sun's topmost layer blows off into space carrying with it magnetic fields still attached to the Sun. Gusts and disturbances form in the solar wind associated with violent...more

Spiral Path of Material

For a planet to be affected by a blob of material being ejected by the sun, the planet must be in the path of the blob, as shown in this picture. The Earth and its magnetosphere are shown in the bottom...more

The SAR Arc

The aurora we are most familiar with is the polar aurora. This is what people are referring to when they speak of the northern or southern lights. But there are other less-known auroral activity, such...more

The Effect of Aurora on the Atmosphere

This figure shows the effect of the aurora on the atmosphere. When FAC's enter the atmosphere and create the aurora, they warm the atmosphere impulsively. This impulse travels throughout the atmosphere...more

The forming Aurora

This picture illustrates the streaming of particles into and out of the auroral zone, as Field-aligned currents (FAC's) short-circuit through the ionosphere. Some of the particles entering the auroral...more

The Expanding Auroral Oval

This figure shows a series of images of the auroral oval as it expands over the course of about an hour in response to a geomagnetic storm. This is an animation of the expanding auroral oval....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