How far is the Sun from Earth?
The Sun is about 150 million kilometers (93 million miles) from Earth on average. Astronomers call this distance one astronomical unit, or AU.
Earth's orbit is slightly oval, so the distance changes during the year. Earth is closest to the Sun, about 147 million kilometers, in early January, and farthest, about 152 million kilometers, in early July. This small difference does not cause the seasons; the tilt of Earth's axis does.
Light from the Sun takes about 8 minutes and 20 seconds to cover this distance. A passenger jet flying nonstop at about 900 km/h would need about 19 years to get there.
How the distance was measured
In the 1700s, astronomers around the world observed Venus passing in front of the Sun and used the timing to estimate the Sun's distance. Today radar signals bounced off planets and spacecraft measurements give the value very precisely. The astronomical unit is now defined as exactly 149,597,870,700 meters.
Did You Know?
The Sun is so big that about 1.3 million Earths could fit inside it, yet from 150 million kilometers away it looks about the same size in our sky as the much smaller Moon.