Mean distance from Sun: 0.39 Astronomical Units
57,900,000 km
Diameter: 4,880 km
Mass: 0.06 Earths
Density: 5.4 grams per cubic centimeter
Surface temperature: 800 F to -360 F
Orbital period: 88 days
Rotational period: 59 days

Mercury is hard to see from Earth because it is so small and so close to the sun. At certain times of the year, it can be seen just after sunset or before sunrise. The rest of the time it is lost in the sun's glare.