Basic Astronomy


(Image Credit: NTs OMZ)

Earth is the 3rd planet from the Sun. Earth is the 5th largest planet in the solar system and it is also the densest planet in the solar system.

Earth formed approximately 4.54 billion years ago, and life started on its surface within one billion years.

Earth is the only known planet in this Universe, which host life.

Equatorial diameter
(Earth diameter)
(Earth mass)
Orbital radius
Orbital period
to Sun's
Orbital eccentricityRotation period
No. of
confirmed moons
6,378.15.9736 x 1024117.250.0171.01

Do you know?
There are NOT 24 hours in a day. Earth takes 23 hr 56 min and 4 sec to rotate once in its axis.
Everyday about 100 tons of small meteorites, mainly tiny fragments of dust, enters Earths' atmosphere.
97% of water on Earth is salted, only 3% is fresh.
90% of all volcanic activity takes place in ocean.
About 75% of animal species of Earth could be extinct by next 300 year.

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