Mercury
Mercury’s elliptical orbit takes the small planet as close as 29 million miles and as far as 43 million miles from the sun. If one could stand on the scorching surface of Mercury when it’s at its closest point to the sun, the sun would appear almost three times as large as it does viewed from Earth.
Temperatures on Mercury’s surface can reach 800° Fahrenheit. Because the planet has no atmosphere to retain that heat, nighttime temperatures on the surface can drop to -280° Fahrenheit.
Because Mercury is so close to the sun, it’s hard to directly observe the Earth except during twilight. Mercury makes an appearance indirectly, however, 13 times each century. Earth observers can watch Mercury pass across the face of the sun, an event called a transit. These rare transits fall within several days of May 8 and November 10.
Scientists used to think that the same side of Mercury always faces the sun, but in 1965 astronomers discovered that the planet rotates 3 times during every 2 orbits. Mercury speeds around the sun every 88 days, traveling through space at nearly 31 miles per second, faster than any other planet. The length of one Mercury day (sidereal rotation) is equal to 58.646 Earth days..