Scorched by the Sun, and scarred by asteroid impacts, Mercury is one of the most extreme planets in our Solar System. At 4873km (3032km) in diameter, it is the smallest of the eight planets. During the day, Mercury’s surface temperature reaches 430C (806F), while at night it falls to -180C (-292F), because Mercury has a very thin atmosphere, that can’t mantain the temperature, so despite that it is the first planet in the Solar System, it is not the hottest! Mercury’s surface is heavly cratered. Other surface features include extinct vulcanos and vast cliffs that are hundereds of kilometers long.
Mercury orbits the sun every 88 Earth days and it’s vertical axis every 59 earth days. It’s distance from the sun varies from only 46 million km (28.6 million miles) at perihelion* to 69.8 million km (43.4 million miles) at aphelion**. Mercury’s core is thought to be composed of iron. It is probbably surrounded by a rocky silicate*** mantle and, on top of that, a silicate crust.
Mercury is visible with the naked eye, shortly before sunrise or just after sunset. Take care to avoid looking at the sun accidently, especially if using binovulars or a telescope.
*smaller distance to the Sun
**larger distance to the Sun
***a compound containing silicon
Smithonisn nature guide – STARS AND PLANETS