Page 6 - Curriculum Visions Dynamic Book

 The Earth and Moon seen from Mars. This is the first-ever picture taken of the Earth and the Moon from another planet. It was taken on May 8, 2003. The view of the Earth shows North and South America. Note that because the Earth is nearer the Sun than Mars, the Earth shows phAses when seen from Mars, just as the Moon does from the Earth.
In fact, rather the opposite has been the
case. That is because since the first space probes we have been able
to look down on our planet and see in it patterns and features that we never even suspected. We have realized that although we walk on its surface every day, we still know remarkably little about the Earth.
Similarly, probes and manned spaceflights have enabled us to see the Moon close up and also the side that we never see from the Earth. Dead it may be, but that has not lessened its fascination. On the contrary, we have become ever more intrigued.
Just as interesting are views of the Earth and the Moon from other planets. Here we can truly see the “blue marble,” as our planet has become fondly known, set like a precious stone within the deep blackness of space.
Rocky bodies
The Earth and the Moon are so very different. But do they have anything in common? Essentially they are both rocky bodies, as opposed to ones made mainly from gas, such as Jupiter or Neptune.
In the Solar System the Earth and its Moon are small
and unusual. In fact, they are too small to hold in place anything more than a thin shell of gases. (Although you may have thought that the Moon has no atmosphere because astronauts wear space suits on the Moon, it does have a very thin atmosphere.) The atmospheres are also quite different from those of the gas giants, or Jovian planets, in the Solar System, having little hydrogen and helium, the gases that dominate these other worlds.
 We are now used to pictures of the Earth like this one, which shows features of the atmosphere as well as of the land and the oceans. Closeup pictures show only part of one side; they do not show the other half.
Use this picture to imagine the features of the Earth as they would be seen from space, just as we view other planets. The Earth is bright and blue, with swirling white clouds formed into belts parallel with the equAtor. Shining white poles indicate snow and ice below. The growth and shrinking of the snow-covered regions through the year would also be noticeable.
The darker surface seen through the clouds is mostly ocean. It would not be easy to identify life on Earth from distant space because most inhabited areas are frequently covered by clouds.
eqUator The ring drawn around a body midway between the poles.
Jovian planets An alternative group name for the gas giant planets: Jupiter, Saturn, Uranus, and Neptune.
phase The differing appearance of a body that is closer to the Sun, and that is illuminated by it.
pole The geographic pole is the place where a line drawn along the axis of rotation exits from a body’s surface.
probe An unmanned spacecraft designed to explore our Solar System and beyond.
For more on the Jovian planets see Volume 5: Gas giants.
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