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Exploratour - The Archean Age

This is an image showing the cratered surface of the planet Mercury.
Click on image for full size
NASA

In addition to being hot, the surface of the Earth was being cratered. Even though the solar system was finished forming, there were still probably a lot of smaller planetesimals and debris around, too. This debris was still able to make a mark on the surface of the Earth. The gravity of the large planets would attract nearby planetesimals, which would hit the planets and leave a crater on the planet's surface.

When we look at images of many of the planets such as Mercury, shown here, we see all sorts of circular craters on the planet surfaces. Most of these craters were probably formed at this period of history. The cratering eventually tapered off, even though craters are still formed on planetary surfaces today.

Subsequent evolution of a planet's surface, driven by activity within the planet itself (if the planet were still active), would wipe out any evidence of this period of cratering. Thus scientists can often trace a planet's age by counting the amount and size of the craters on the surface.



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Traveling Nitrogen Classroom Activity Kit

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

ExploraTour - Looking at the World in a Different Light

Even though the sleeping man is no longer on the bed, you can still see where he was lying down. The heat from his body warmed up the bed sheets which are now radiating infrared light toward your eyes....more

ExploraTour - Looking at the World in a Different Light

All warm objects (not just people) radiate in the infrared. Warmer objects give off more infrared radiation. Very hot objects radiate other types of light in addition to infrared. Click on the picture...more

ExploraTour - Looking at the World in a Different Light

Your eye is a wonderful detector of visible light. Different frequencies of light produce different sensations in the eye which we interpret as colors. Our eyes detect light by using light sensitive components...more

ExploraTour - Looking at the World in a Different Light

Imagine you found a pair of special glasses that not only gave you telescopic vision but gave you the ability to see all forms of radiant energy. The universe in visible light contains all the familiar...more

ExploraTour - Looking at the World in a Different Light

This is a volcano on the island of Miyake in Japan. It has erupted, sending hot lava and ash into the air, a total of ten times. The time after one eruption until the next occurred was about twenty years...more

ExploraTour - Looking at the World in a Different Light

This is a picture of a galaxy in visible light. A galaxy is a large number of stars, some like our sun, some bigger, some smaller and all moving together through space. This galaxy is called Centaurus...more

ExploraTour - Looking at the World in a Different Light

This is a plant in Gary, Indiana where power is made. We use power to run things like television sets, radios, lights, and microwave ovens. The picture looks very strange because it was taken in infrared....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