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Oct '23
Mercury is the first planet from the Sun. It is the second hottest planet, behind Venus. It is the smallest planet in the Solar System, even being smaller than the moons Titan (of Saturn) and Ganymede (of Jupiter). With a diameter of 4880 km, compared to the 5150 and 5270 km of the 2 moons. The temperature on Mercury is 430°C at day, but at night, temperatures on Mercury can decrease to -180°C. Mercury spins very slowly, having a rotation period of 56 days, and a orbital period of 89. Mercury possesses a very thin atmosphere that allows most of the space radiation, heat, and cold from the sun to hit it’s surface, and stay.
Formation
There are three main theories of how Mercury was formed. They are listed below.
- Mercury could have been a gas giant (most likely a Hot Jupiter) that started orbiting too close to the Sun, and got its atmosphere vaporized, only leaving its molten, rocky core behind, that slowly cooled down.
- Mercury formed just like all the other terrestrial planets, as first a volcanic clump of asteroids and particles. It was the third planet from the Sun but its orbit was disturbed by the Sun's gravity and was placed as the first planet.
- Mercury was once a twin planet with Venus but got pulled inward towards the Sun, and flew into an orbit around it.
Atmosphere
Mercury has a thin exosphere made of around 40% oxygen, about 20% sodium, around 22% hydrogen and 10% helium. The other 1% of the exosphere is made of other trace gases. The atmosphere is created by the heat within the planet radiating out and its surface degassing itself.
Surface
The surface of Mercury has many craters, the largest and most well known of all the craters being the Caloris Basin, a massive crater being around 1600 km in diameter from side to side. Ancient volcanoes present signs that volcanism was previously active on Mercury. The rest of the surface are cliffs amd plains that became solid, which is a process called solidification. This solidification also created the volcanoes, and is present on Earth as well.
Structure
Internal Structure of Mercury -1. Crust - 100-300 km thick2. Mantle - 600 km thick 3. Core - 1,800 km radius
The core is thought to be made of iron, which is what happened due to the amount of accretion from the nebula that Mercury received when the nebula created the solar system. Around it is a mantle, made of silicate, where the convection currents take place. The last, and top, is the crust, that suffers from asteroid impacts and volcanoes. Mercury is also shrinking, though it happens very slowly.
Observation
Mercury can easily be seen during twilight or just after the sunset. The visibility cannot remain for long due to its very fast orbit around the Sun. The elongation, or the point at which a celestial object is at its farthest point from a solar remnant, of Mercury from the Sun is the best time to view it, although this event only occurs about seven times a year.
Trivia
- Mercury will be swallowed by the Sun in its red giant phase in around 7.8 billion years from now.
- Mercury is the only planet in our Solar System to be tidally locked to the sun, meaning one side of the planet always faces the sun.
- Mercury has the most eccentric orbit compared to the other planets in the Solar System.
Gallery
See Also
| Geology of Mercury | |
|---|---|
| Mountains and volcanoes | Caloris Montes |
| Plains and plateaus | Borealis Planitia • Budh Planitia • Caloris Planitia • Odin Planitia • Sobkou Planitia • Suisei Planitia • Tir Planitia |
| Canyons and valleys | Arecibo Catena • Arecibo Vallis • Goldstone Catena • Goldstone Vallis • Haystack Catena • Haystack Vallis • Simeiz Vallis |
| Ridges and rupes | Antoniadi Dorsum • Adventure Rupes • Beagle Rupes • Discovery Rupes • Enterprise Rupes • Hero Rupes • Resolution Rupes • Santa María Rupes • Victoria Rupes |
| Basins and fossae | Caloris Basin • Pantheon Fossae • Raditladi Basin • Rembrandt Basin • Skinakas (hypothetical basin) |
| Craters (largest) | Caloris • Rembrant |
| The Planets and Dwarf Planets | |
|---|---|
| Planets | |
| Inner: (Mercury • Venus • Earth • Mars) Outer: (Jupiter • Saturn • Uranus • Neptune) | |
| Dwarf Planets (and candidates) | |
| Ceres • Pluto • Haumea • Makemake • Quaoar • Orcus • Eris • Gonggong • Sedna | |