Exploring the Moon
How big is the moon?
The moon is about 2,000 miles across.
How far is it from Earth to the moon?
It is about 250,000 miles from Earth to the moon.
How old is the moon?
The moon is the same age as the Earth and the rest of the solar system — about 4.5 billion years. Our solar system was all formed at that time.
The Moon's Surface
The surface of the moon has about two inches of dust. Much of this dust has fallen to the moon from the spaces between the planets over the last several billions years. It probably feels pretty soft. You can see this in some pictures taken by the astronauts of their footprints on the moon.
How come we can sometimes see the moon during the day?
The reason that you don't see the stars during the day is that the sky is too bright. Sunlight scatters around in the air and makes the sky look bright blue. But if you had a telescope and pointed it at a bright star you could still see it during the day! The stars are still there, just hard to see. The moon is bright enough that we can see it during the day or night. It orbits Earth once every 29 days. So during some of that time, it is easiest to see during the day and sometimes during the night.
Is there really water on the moon?
Water that would be found on the moon may have existed from the days when our solar system was formed. Comets that may have hit the moon could also be a source of water. Generally we think water, that was part of the moon as it formed, would have probably evaporated away. Water from comets would have evaporated too. However, the area where Clementine found the possible signature of water is at the very cold south pole of the moon, in a dark, cratered area where the sun never shines. So it seems possible that the water (or ice) has survived there. We are hoping that other observations can be made with other satellites that can confirm whether this is really water on the moon. If so, it would be a great help for manned space travel in the solar system!
If there is no weather or atmosphere on the moon, then where does the ice come from?
We think that the ice on the moon came from comets! Comets are made up of mostly ice with some rocks and dirt mixed in. We think that most of the water on the earth probably came from comets that crashed into the earth when the earth was very, very young. The ice on the moon may have come the same way. Most of the water on the moon evaporated away a long time ago. But the ice at the South Pole stayed there because it is very, very cold and is in a dark area where the sun never shines.
Why does the moon affect the tides?
The moon actually CAUSES the tides. If there were no moon, we would have no tides. The tides arise due to the pull of the moon's gravity. On the side of Earth nearest the moon, the moon's gravity is the strongest and it pulls up the water slightly (high tide). On the side of Earth furthest from the moon, the moon's gravity is the weakest and the water can move a little away from the moon (which is also high tide). This also affects Earth itself. During high tide Earth rises by an inch or two, not enough for us to notice.