Astronomers have mapped neutral atomic hydrogen, which profuses the space between stars, in unprecedented detail to create a beautiful radio-wavelength portrait of the Milky Way.
Astronomers have observed the motion of distant star clusters to measure our galaxy’s mass. The new estimate places the Milky Way in the lightweight class of galaxies.
Stellar streams are the remains of dwarf galaxies that once orbited the Milky Way. We showcase here stunning images of these galactic ghosts.
Do astronomers have any idea what percentage of our galaxy’s stars move in retrograde orbits? The short answer is yes, a very small percentage. But the long answer is more interesting. First, let’s agree what we mean by “retrograde.” If you were to look down on the solar system from the north ecliptic pole in…