From The Conversation · Edwin Alexani · · 1m 20s
Why do galaxies rotate?
Galaxies spin due to conservation of angular momentum from early cosmic collisions.
In brief
Galaxies spin due to conservation of angular momentum from early cosmic collisions. Galaxies rotate because collisions during formation conserved angular momentum. Originally reported by The Conversation.
Quick answers
- Why do galaxies rotate?
- Galaxies spin because early cosmic collisions conserved angular momentum.
- What is the key takeaway from Why do galaxies rotate??
- Galaxies rotate because collisions during formation conserved angular momentum.
Why do galaxies rotate?
Galaxies spin because early cosmic collisions conserved angular momentum.
Spinning in space
Spinning is common in space, from Earth to the Milky Way and many objects.
Angular momentum
The amount of spin an object has depends on its mass and how mass is distributed around its center of mass.
Conservation of angular momentum
Pulling mass closer to the center of mass increases spinning speed, as seen in figure skaters and chairs.
Galaxy formation
Galaxies form from gas and dust clouds colliding, which often start spinning due to off-center approaches.
Dark matter's role
Dark matter helps pull gas and dust clouds together through gravity, aiding galaxy formation.
Spiral galaxies
Spiral galaxies have a flat disk with spiral arms and a central bulge, where most matter rotates in the same direction.
Elliptical galaxies
Elliptical galaxies have few gas and dust, with stars orbiting the center but no organized rotation.
Galaxy rotation types
Irregular galaxies have general rotation but some objects do not follow it, while others spin more organized.
The big picture
Galaxies rotate because collisions during formation conserved angular momentum.
