The summer constellation Sagittarius the Archer lies in the direction to the center of our Milky Way galaxy. There, stars and gas clouds move in chaotic orbits. Does that mean they often collide?
Are the stars and gas clouds in the spherical bulge at the Milky Way’s center more likely to collide than stars and gas clouds in our part of the Milky Way?
The spiral arm region of the galaxy — where we live — is like a one-way freeway. Most all the stars move in the same direction as they orbit the Milky Way’s center. So they tend not to cross paths. Meanwhile, the bulge of stars at the galactic center is like a swarm of bees. The stars move in random orbits and do cross paths frequently.
Even so, star collisions are unlikely in the bulge at the center of the galaxy — because, even there, stars are tiny compared to the distances between them. If our sun were the size of a pea, the nearest star would be 200 kilometers — or 120 miles — away. But, even across great distances, stars interact — through the powerful pull of gravity. In the galactic bulge, each star is affected by the collective gravity of the other stars — and so the stars move in chaotic orbits.
Gas clouds in the galaxy are light-years wide — and their size makes them prone to collisions. And those collissions are what spark the birth of new stars. Gas clouds in the Milky Way’s central bulge collide frequently — so that part of the galaxy is lit by the bright light of many new stars.