Galaxies, Page 85: [Previous Page] [Next Page] [Class Home Page] Textbook pages 432 -434

But Wait! There's More!

If one looks at the velocities (measured through Doppler Shift) of galaxies in a cluster, the galaxies appear to be responding to a LOT more mass in the cluster than is actually seen (traveling at very high velocties). There must be a lot of matter there to hold the galaxy cluster together.

We can even directly measure the dark matter as it bends the light of distant galaxies. This is called gravitational microlensing, and is seen in this image:

To see a movie of a model of a cluster (yellow galaxies) moving in front of background galaxies (faint blue galaxies) and gravitationally lensing them, click here.