News tagged with years

How small can galaxies be?

Yesterday I talked about just how small a star can be, so today let's explore just how small a galaxy can be. Our Milky Way galaxy is about 100,000 light years across, and contains about 200 billion stars. Th ...

22 hours ago
4.9 / 5 (15) 14

Measuring the proper motion of a galaxy

The motion of a star relative to us can be determined by measuring two quantities, radial motion and proper motion. Radial motion is the motion of a star along our line of sight. That is, motion directly ...

Sep 23, 2014
4.8 / 5 (6) 1