Re: How would Earth look like from space if it didn't have an atmosphere?

This is an interesting thought question. I'll give you 2 of my interpretations, 2 extreme time periods...you should think about how Earth would change over time.

If the Earth had no atmosphere over a long period of time, all the water and ice would evaporate into space, leaving behind land masses (the continents) and gigantic open spaces (the oceans). Impacting objects, no longer slowed and destroyed by the atmosphere, would leave craters all over the Earth, as seen on the surface of the Moon. More than likely, the harmful solar UV radiation that is mostly blocked by our atmosphere, would destroy vegetation, if it even had a chance to develop at all. The surface would then resemble that of a desert.

If, however, you take away the atmosphere for only a brief time period and retain all of Earth's features, particularly the oceans, it would still look quite different when viewed from space. First of all, the oceans would appear black, since they are no longer reflecting the blue sky. Instead, they would reflect the darkness of space. We wouldn't be able to see any cloud formations either, so there would be no cloud shadows on the Earth's surface.

Think about other things that the atmosphere does - it reflects light back to the surface, creating the greenhouse effect, it allows cloud formation for rain storms, it regulates wind patterns... Over time, the lack of these phenomena will affect how the Earth looks from space.

Our atmosphere protects us from impacting objects as well as from harmful UV radiation and cosmic rays. Depending on the time-scale, the lack of atmosphere could greatly affect living organisms and their environments on Earth.

For more information about the Earth and its atmosphere, see http://seds.lpl.arizona.edu/nineplanets/nineplanets/earth.html