The Sun is, at present, about 70% hydrogen and 28% helium by mass everything else ("metals") amounts to less than 2%.
Mercury is the closest planet to the Sun and the eighth largest.
Mercury has been now been visited by two spacecraft, Mariner 10 and MESSENGER
Temperature variations on Mercury are the most extreme in the solar system ranging from 90 K to 700 K.
Mercury is in many ways similar to the Moon: its surface is heavily cratered and very old
In addition to the heavily cratered terrain, Mercury also has regions of relatively smooth plains. Some may be the result of ancient volcanic activity but some may be the result of the deposition of ejecta from cratering impacts.
Venus is the second planet from the Sun and the sixth largest
Venus is sometimes regarded as Earth's sister planet. In some ways they are very similar
Venus probably once had large amounts of water like Earth but it all boiled away
The Earth is the densest major body in the solar system.
Earth has only one natural satellite, the Moon.
Most of the mass of the Earth is in the mantle, most of the rest in the core; the part we inhabit is a tiny fraction of the whole the crust
Mars is the fourth planet from the Sun and the seventh largest:
The first spacecraft to visit Mars was Mariner 4 in 1965
Though Mars is much smaller than Earth, its surface area is about the same as the land surface area of Earth.
Jupiter is the fifth planet from the Sun and by far the largest
Jupiter was first visited by Pioneer 10 in 1973 and later by Pioneer 11, Voyager 1, Voyager 2 and Ulysses.
Jupiter is about 90% hydrogen and 10% helium (by numbers of atoms, 75/25% by mass) with traces of methane, water, ammonia and "rock"
Saturn is the sixth planet from the Sun and the second largest:
Saturn was first visited by…