[[ឯកសារ:AxialTiltObliquity.png|thumb|right|200px|Earth's axial tilt (or obliquity) and its relation to the [[Rotation|rotation axis]] and [[Orbital plane (astronomy)|plane of orbit]].]]
The Earth takes about 24 hours to complete one [[day]] and about 365 days to complete a [[year]]. Actually, the Earth takes 365.24 days to revolve around the sun.<ref name=IERS>{{cite web | author=Staff | date=2007-08-07 | url=http://hpiers.obspm.fr/eop-pc/models/constants.html | title=Useful Constants | publisher=International Earth Rotation and Reference Systems Service| accessdate=2008-09-23 }}</ref> To make up this quarter day every year, an extra day is added every four years making the year 366 days. This is a [[leap year]]. The Earth is, on [[wikt:average|average]], 150 million kilometers away from the Sun, and moving at a speed of 30 kilometers a second or 108,000 miles an hour.<ref>{{citeweb|url=http://nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html|title=NASA- an Earth fact sheet|accessdate=2009-08-06|publisher=NASA}}</ref>
[[The Moon]] orbits the Earth at an average distance of 250,000 miles. It is [[tide|tidally]] locked to Earth, which means it always has the same side facing the Earth. It takes roughly one [[month]] to complete one orbit.
