Sagittarius

Our solar system is on a high-speed merry-go-round. The Sun orbits the center of the Milky Way Galaxy at half a million miles per hour.

The center of the galaxy is in Sagittarius. The constellation rolls low across the southern sky on summer nights. Some of its bright stars form the outline of a teapot. The galactic center is above the “spout” of the teapot — immersed in the faint “steam” of the Milky Way.

We’re roughly 27,000 light-years out from the center. At that distance, it takes the solar system about 230 million years to complete a single revolution.

The solar system’s orbit isn’t a smooth path, though. If you could plot it out, you’d see a lot of little bumps and wiggles. That’s because the galaxy itself isn’t smooth and even. Instead, it’s “lumpy.” There are clusters of stars, big clouds of gas and dust, and other structures. So as the solar system passes by these objects, it’s tugged by their gravity, slightly changing its orbital path. And we pass through some of the clouds of gas and dust, which also alters the solar system’s path.

The solar system has been around for about four and a half billion years. That means it’s completed roughly 20 orbits around the galaxy. And it’ll probably make another 25 or more before the Sun reaches the end of its “normal” lifetime — more high-speed rides on a galactic merry-go-round.

We’ll talk about some stellar nurseries in Sagittarius tomorrow.

Script by Damond Benningfield