The Milky Way is a barred spiral galaxy with a diameter between 150,000 and 200,000 light-years. It is estimated to contain 100–400 billion stars and more than 100 billion planets. The Solar System is located at a radius of about 27,000 light-years from the Galactic Center.
From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within. It has been proposed that the Milky Way lacks a bulge formed due to a collision and merger between previous galaxies and that instead, it only has a pseudo-bulge created by its central bar.
Farther from the galactic center, it is warped, with one side swung upward and the other downward. The warp starts to take effect in the outer reaches of the galaxy, in the direction opposite the galactic center in Sagittarius, if you are looking at it from Earth.
Milky Way Galaxy’s Warp Orbits The Galactic Center Once Every 600 Years
Using data from the space observatory Gaia, last year, scientists tried to chart the warp’s shape precisely. Now, they used Gaia again to see how that warp processes around the center. Precession is a change in the orientation of the rotational axis of a rotating body.
Measuring the apparent motions of millions of stars can help to model the movement of the warp also. Stars and gases at a wide range of distances from the Galactic Center orbit at approximately 220 kilometers per second. The Milky Way as a whole is moving at a velocity of roughly 600 km per second.
Now, the warp turned out to be turning prograde. It speeds at 10 km/s per kiloparsec away from the galactic center in the direction of the galaxy’s rotation. This means that at the Sun’s location, the warp is changing the orientation at 80 km/s.
The Sun needs 250 million years to circle the galaxy. The warp needs 600 or 700 million years to do it. A lot faster than previously believed.
