Planet Mercury is named after the Roman messenger god. It is the closest planet to the Sun and is the second smallest.
The picture to the left shows Mercury's surface being almost identical to the Moon. It is covered in a massive number of craters and is definitely more cratered than the Moon.
The craters would have been formed in the early life of Mercury when it would have been struck by hundreds of meteorites left over from the creation of the Solar System. The biggest crater is the Caloris Basin, which is 808 miles wide.
The core of the planet, which is visible in the illustration below, appears to be slightly molten. It is made out of iron and accounts for 70% of Mercury's mass.
|Planet Mercury is a stark barren world with many surface features. The crater near the centre is called Kuiper and a closeup can be seen below. This stunning image was taken last year in 2008 by the Messenger space probe, the second visitor to Mercury.|
|Image copyright NASA/John Hopkins University Applied Physics Laboratory /Carnegie Institution of Washington|
Mercury has a temperature of 700 degrees Farenheit during the day and a chilly minus 300F at night.
Interestingly the sky of Mercury is black because the planet has no atmosphere to scatter the Sun's light.
Mercury orbits the Sun at an incredible speed because of its close proximity to the Sun. The Sun's massive gravity creates a warp that directly affects the orbit of Mercury.
|Interior of Mercury.|
|Image copyright N. Fuller|
The only 20th century space probe that visited Mercury was Mariner 10 in 1974.
In 2008, a new space probe called Messenger did a flyby of Mercury and imaged the whole planet. It also discovered never before seen surface features that included surface faults.
Distance from Sun: 35,983,095 miles
Diameter: 3032 miles
Length of Day: 58.7 days
Length of Year: 88 days
Number of moons: 0
The crater Kuiper is unique as it has an ejecta ray system. These are found around other craters on Mercury and a formed by subsurface material being excavated by the impact. It is named after the Dutch astronomer, Gerard Kuiper who was on the Mariner 10 team. This image was taken by the Messenger probe.
|An unnamed basin feature that was discovered by Messenger. It is 430 miles in diameter and is interesting as there are many radial fractures on the basin floor.|
|Image copyright NASA/John Hopkins University Applied Physics Laboratory/ Carnegie Institution of Washington|
|Image copyright NASA/John Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington|