Facts about Earth

• Third planet from the Sun
• It’s a Terrestial Planet and HOME!

Diameter: 7,926 miles
Mass: 1 Earth mass
Density: 5.52 where water = 1
Gravity: 32.2 feet/sec2
Albedo (% of Sunlight reflected): 37%
Rotation on Axis: 24 hours, 56 min, 4.1 sec
Inclination of Axis to Orbit: 23.4°

Distance from Sun: 92,955,800 miles
Revolution about Sun: 365.26 days
Inclination of Sun to Earth’s Orbit: 7.2°

Atmosphere: 77% Nitrogen, 21% Oxygen, 1% water, 0.9% Argon, plus traces of other gases
Surface Temperature: Averages 59° F
Atmosphere Pressure: 14.7 lb/inch2

Moon: Only one.

See more facts about Earth at the bottom of this page!

Picture to the right was taken during the Apollo 17 mission that went to the Moon in 1972.

THE PLANET EARTH

The Earth is our home, and as far as we know, the only planet with life. No one understands exactly how life developed on Earth, but scientists feel certain that two major factors are necessary for life to start and then to flourish. First, a planet must have liquid water. Our Earth’s surface is 71% water. Second, the temperature must stay in a narrow range. If the Earth were just a little closer or a little farther away from the Sun than it is now, it would be either too hot or cold for life to flourish. There are many other factors necessary for life to flourish, but if these two conditions were not met, humans, animals and plants would not exist in the abundance that they do now.

Earth from the Moon.

Earth from the International Space Station.

Space sunset.

We might think we know Earth but here is a picture taken from orbit showing a volcanic area of Saudia Arabi. The Earth has an incredibly diverse surface.

What’s Out Tonight? is sponsored by Ken Press, publisher of astronomy books and charts.
Phone: (520) 743-3200 • Fax: (520) 743-3210 • Email: ken@kenpress.com