3
20
Mercury is a tiny black dot as it transits the Sun in 2006.
There are a couple of different ways to measure how “big” something is. The first is an object’s mass (how much matter it contains) and the second is its volume (how much space it takes up). The smallest planet in regards to both mass and volume is Mercury — at 4,879 km across and 3.3010 x 1023 kg, this tiny world is nearly 20 times less massive than Earth, and its diameter is about 2½ times smaller. In fact, Mercury is closer in size to our Moon than to Earth.
i want to add some facts about this plannet although your post is good but it need some amendments
so the addition is here
Mercury does not have any moons or rings. Mercury is the smallest planet. Mercury is the closest planet to the Sun. Your weight on Mercury would be 38% of your weight on Earth. A day on the surface of Mercury lasts 176 Earth days. A year on Mercury takes 88 Earth days. It’s not known who discovered Mercury.
Mercury is the smallest planet in the Solar System. One of five planets visible with the naked eye a, Mercury is just 4,879 Kilometres across its equator, compared with 12,742 Kilometres for the Earth.
Mercury has a molten core. In recent years scientists from NASA have come to believe the solid iron core of Mercury could in fact be molten. Normally the core of smaller planets cools rapidly, but after extensive research, the results were not in line with those expected from a solid core. Scientists now believe the core to contain a lighter element such as sulphur, which would lower the melting temperature of the core material. It is estimated Mercury’s core makes up 42% of its volume, while the Earth’s core makes up 17%.
Only two spacecraft have ever visited Mercury. Owing to its proximity to the Sun, Mercury is a difficult planet to visit. During 1974 and 1975 Mariner 10 flew by Mercury three times, during this time they mapped just under half of the planet’s surface. On August 3rd 2004, the Messenger probe was launched from Cape Canaveral Air Force Station, this was the first spacecraft to visit since the mid 1970’s.
Mercury is named for the Roman messenger to the gods. The exact date of Mercury’s discovery is unknown as it pre-dates its first historical mention, one of the first mentions being by the Sumerians around in 3,000 BC. Mercury has an atmosphere (sort of). Mercury has just 38% the gravity of Earth, this is too little to hold on to what atmosphere it has which is blown away by solar winds. However while gases escape into space they are constantly being replenished at the same time by the same solar winds, radioactive decay and dust caused by micrometeorites.