Sun Orbit

by Fraser Cain on September 12, 2008

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Position of the Sun in the Milky Way. Image credit: NASA

Position of the Sun in the Milky Way. Image credit: NASA

Everything’s orbiting something it seems. The Moon goes around the Earth, and the Earth orbits the Sun. But did you know that the Sun orbits the Milky Way galaxy?

Astronomers have calculated that it takes the Sun 226 million years to completely orbit around the center of the Milky Way. In other words, that last time that the Sun was in its current position in space around the Milky Way, dinosaurs ruled the Earth. in fact, this Sun orbit has only happened 20.4 times since the Sun itself formed 4.6 billion years ago.

Since the Sun is 26,000 light-years from the center of the Milky Way, it has to travel at an astonishing speed of 782,000 km/hour in a circular orbit around the Milky Way center. Just for comparison, the Earth is rotating at a speed of 1,770 km/h, and it’s moving at a speed of 108,000 km/h around the Sun.

It’s estimated that the Sun will continue fusing hydrogen for another 7 billon years or so. In other words, it only has another 31 orbits it can make before it runs out of fuel.

Are you interested in more articles about the Sun? We have written plenty for Universe Today. Here’s an article that shows how some stars take an erratic journey around the Milky Way, and another article about a ring of stars orbiting the Milky Way.

Here’s an article that describes the process astronomers used to determine the orbit around the Milky Way.

We have recorded an episode of Astronomy Cast just about the Sun called The Sun, Spots and All.

References:
NASA Imagine the Universe!
NASA Spacemath
NASA Solar System Exploration Page

About 

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay.

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