To find your age on the outer planets (Jupiter, Saturn, Uranus, Neptune, and Pluto), divide your age in Earth years by the approximate length of the planet’s year in Earth years. This is your “new” age. For example, a 20 year old on Earth would only be 1.7 years old on Jupiter because 20 / 12 = 1.7.

Why does the Moon have so many craters while Earth has so few? On Earth, impact craters are harder to recognize because of weathering and erosion of its surface. The Moon lacks water, an atmosphere, and tectonic activity, three forces that erode Earth’s surface and erase all but the most recent impacts.

Meteorite craters are more common on the Moon and Mars and on other planets and natural satellites than on Earth, because most meteorites either burn up in Earth’s atmosphere before reaching its surface or erosion soon obscures the impact site. …

The real reason there are more impact craters on the far side of the Moon is that the near side has a much thinner crust which has allowed volcanoes to erupt and fill in ancient large basins (or large impact craters).

The ages of the surfaces of objects in the solar system can be estimated by counting craters: on a given world, a more heavily cratered region will generally be older than one that is less cratered. In this way, we have estimated the age of the Moon and Earth to be roughly 4.5 billion years.

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South Pole-Aitken basin

Simple craters like Moltke (which is 6.5 km in diameter and 1.3 km deep), have a smooth bowl-like shape with smooth walls. Most small craters less than about 15 km in diameter are simple craters. For a details map of the Moon’s surface with craters, see Google Moon.