Diameter: 4879 km
SMA: 0.387098 AU
Period: 0.2410 years
Eccentricity: 0.20563
Rotation: 115.88 days
Inclination: 7°
Axial tilt: 0.01°

Mass: 3.3011x10²⁴kg
Density: 5427 kg/m³
Gravitation: 3.7 m/s²
Escape velocity: 4.3 m/s
Orbit velocity: 47.87 km/s (mean)

Moons: 0
traces of hydrogen and helium
basaltic and anorthositic rocks and regolith

Mercury's eccentric orbit takes the small planet as close as 47 million km (29 million miles) and as far as 70 million km (43 million miles) from the sun. If one could stand on the scorching surface of Mercury when it is at its closest point to the sun, the sun would appear more than three times as large as it does when viewed from Earth. Temperatures on Mercury's surface can reach 800 degrees Fahrenheit (430 degrees Celsius). Because the planet has no atmosphere to retain that heat, nighttime temperatures on the surface can drop to -290 degrees Fahrenheit (-180 degrees Celsius).

Because Mercury is so close to the sun, it is hard to directly observe from Earth except during dawn or twilight. Mercury makes an appearance indirectly -- 13 times each century, observers on Earth can watch Mercury pass across the face of the sun, an event called a transit. These rare transits fall within several days of 8 May and 10 November. The first two transits of Mercury in the 21st century occurred 7 May 2003, and 8 November 2006. The next are 9 May 2016, and 11 November 2019.