The Solar System (Mercury)

Mercury captured by MESSENGER.
Credits: NASA.

Mercury transits across the sun in 2016.
Credits: NASA/ SDO satellite

Mercury is transitioning across the sun.
Credits: JAXA.

    Mercury, the smallest and closest planet to the sun, is very much like our moon, but a little bigger. Named after the Roman gods of the swiftest, this planet does rotate around the sun at a quick speed of 29 miles per second, completing the orbit around the sun every 88 days, but is not the hottest of all planets (Venus is), but does have an extreme temperature change between night and day. However, Mercury's egg shaped orbit can get the planet as close as 29 million miles or as far as 43 million miles from the sun, but on the planet, the sun appears to be three times bigger, with 11 times more sunlight, and at such a distance, light takes three minutes to reach the planet, so on a scale, Mercury is still pretty far from the sun, and from Earth, you can only see the planet before sunrise and right after sunset, and every few years you can see the planet transit across the sun.

The first and last shot from the MESSENGER probe.
Credits: NASA.

     A day on Mercury takes 176 Earth days, with daytime temperatures of 800 degrees Fahrenheit, and a temperature of -290 degrees Fahrenheit at nighttime, least likely that the planet is habitable. NASA explains, "Mercury spins slowly on its axis and completes one rotation every 59 Earth days. But when Mercury is moving fastest in its elliptical orbit around the Sun (and it is closest to the Sun), each rotation is not accompanied by a sunrise and sunset like it is on most other planets. The morning Sun appears to rise briefly, set and rise again from some parts of the planet's surface. The same thing happens in reverse at sunset for other parts of the surface. One Mercury solar day (one full day-night cycle) equals 176 Earth days—just over two years on Mercury. Mercury's axis of rotation is tilted just 2 degrees with respect to the plane of its orbit around the Sun. That means it spins nearly perfectly upright and so does not experience seasons like many other planets do." Mercury's rotation doesn't have sunrise and sunsets like how our days would have it, the sun can rise and set multiple times a 'Mercury' day, and also there are no seasons on Mercury, for its axis is almost perfectly upright, so there is no season changes.

Southern hemisphere of Mercury captured by Mariner 10.
Credits: NASA/JPL.

      Mercury, like the moon is scarred and blasted with a lot of outside bodies of rocks, that revolve around the sun, and crashes into the little planet. So crashes gives the planet miles of cliffs, and elevation, however these cliffs rose to the surface as the planet's interior activity cooled down. NASA supports, "Most of Mercury's surface would appear greyish-brown to the human eye. The bright streaks are called "crater rays." They are formed when an asteroid or comet strikes the surface. The tremendous amount of energy that is released in such an impact digs a big hole in the ground, and also crushes a huge amount of rock under the point of impact. Some of this crushed material is thrown far from the crater and then falls to the surface, forming the rays. Fine particles of crushed rock are more reflective than large pieces, so the rays look brighter. The space environment—dust impacts and solar-wind particles—causes the rays to darken with time." Mercury has a lot of scar, which are caused by energy from the impact of asteroids and causes fine particles of the rocks to fly up and then settle on the planet, thus creating scars, which are bright, but then darkens as dusts and solar winds touches it over time. Ice does exists on the planet. For it is so cold, and the planet's irregular orbit and rotation, some parts of the planet never receives sunlight, thus is where the ice are in deep craters of the planet, despite the heat of the sunlit parts of the planet.

Mercury's polar craters, (see the ice?)
Credits: NASA

    With no atmosphere, Mercury has another protective layer, the exosphere, created mostly with hydrogen, helium, potassium, and oxygen at very minimal amounts. The exosphere of Mercury's come from the solar wind, surface of the planet from micrometeorite crashes, and radioactive decay on the planet. However, Mercury does have a magnetic field, although its only 1% compared to Earth's, and it interacts with the magnetic field of the solar winds, sometimes causing magnetic tornadoes that knock the planets neutrally charged particles into the air, thus creating the planet's atmosphere.

The Abedin Crater was formed by once molten rocks,
shows that the planet had once volcanic activity.
Credits: NASA

      Not a lot of probes have passed or orbited to the planet, but NASA had sent Mariner 10, which captured about 45% of the planet, and MESSENGER, which flew by the planet three times, and orbited the rocky planet for four years before crashing into the surface of the planet. The ESA is planning to launch a probe to discover the small planet later this year (2018).

Bibliography:

"Mercury" NASA. May 7, 2018. Retrieved at October 7, 2018 from:  https://solarsystem.nasa.gov/planets/mercury/overview/.  https://solarsystem.nasa.gov/planets/mercury/in-depth/.