Please I need 4 explanations.
I already have different atmospheres
2007-01-11 12:13:46 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
For the same reason the Moon is plastered with thousands of craters: the lack of an atmosphere. Earth has craters (See link: http://en.wikipedia.org/wiki/Meteor_Crater ), but most impacts probably can't be seen because 78% of our surface is oceans, compared to the other planets, which have no water.
Secondly, Mercury is very close to the Sun, which acts as a huge magnet for space objects that windup hurling towards the Sun but strike Mercury instead.
Thirdly, the outer "Gas Giants" have a very dense atmosphere, so craters won't be visible. If you look at Jupiter and Saturn's moons, however, you see the numerous impacts that aren't visible on the planet's surface.
Fourth, Plate Tetonics and erosion is changing our surface and "erasing" craters.
2007-01-11 12:30:23 · answer #1 · answered by Dr. Bob 1 · 3⤊ 0⤋
Hundreds of craters have now been identified on Earth, but others are on the sea bed, been eroded or have been subducted by plate tectonics. That latter completely obliterates the older craters.
Earth will have been hit about 15 times more than the moon, as it has about 15 times the surface area. On the moon, the scars are not covered up.
Same with the gas giants. Jupiter was hit with a long train of comets in 1994, witnessed by thousands of astronomers. There are no craters because Jupiter has a dynamic environment, always changing.
Earth doesn't change so quickly, so craters will hang around for thousands to millions of years. But after that, they will be worn away, and later churned into the mantle by tectonic movement.
2007-01-11 13:34:04 · answer #2 · answered by nick s 6 · 3⤊ 0⤋
1. The presence of a thick atmosphere will cause small objects to burn up as they enter. Mars and Mercury have minimal to no atmosphere.
2. The presence of the Moon can act as a gravitational guard to deflect or attract some of the objects away from the Earth. The other planets have either no moon or very miniscule moons.
3. An active geology including subduction of continental plates as well as air and water erosion.
4. The presence of water over most of the surface hides craters and cushions the impact of objects.
2007-01-11 12:25:24 · answer #3 · answered by eriurana 3 · 3⤊ 0⤋
Simply put, earth has a very active atmosphere which those other planets lack. Craters are quickly eroded away although traces of a few big ones can still be found. Earth, being bigger than Mercury and the moon put together, has actually had more hits than either of those. It's just that they don't stay around long because of wind and rain and our fairly active tectonic plates.
2007-01-11 15:19:33 · answer #4 · answered by kevpet2005 5 · 1⤊ 1⤋
Erosion and plate tectonics, the earth tends to clean itself up. However, there are more ancient craters visible on the earth than you think. When studied from space, remains of old craters can be seen on every continent. Many have even been found on the ocean floor.
2007-01-11 16:34:08 · answer #5 · answered by ZeedoT 3 · 3⤊ 0⤋
1. As you said, different atmospheres.
2. Erosion
3. Plate Tectonics
4. Nearly 75% of our planet is covered by water
2007-01-11 12:18:14 · answer #6 · answered by Anonymous · 3⤊ 0⤋
Our moon tends to sweep away potential impactors by atracting them. Our atmosphere is thicker than the other planets as well, so smaller meteors burn up before impact.
2007-01-11 12:28:30 · answer #7 · answered by DT 4 · 0⤊ 3⤋
Well, i don't know if you can use this, but Earth was DESIGNED for life to thrive, the other planets were not.
2007-01-11 12:22:04 · answer #8 · answered by Anonymous · 1⤊ 3⤋