How Astronomers Use Mass to See into the Past

Einstein's Lens

On the upper right is a computer reconstruction of a more distant galaxy.     The middle image is of a galaxy closer to us.  It is the massive galaxy that is producing the lens effect.  The bottom image is the distant galaxy with the foreground 'lens' removed

13/01/2009 04:25 PM


  • As we look up into the night sky, we are seeing into the past.  The vast distances that light has to travel to get to us means that we are seeing objects as they appeared in the distant past.  Closer to home it takes about 1.3 seconds for the Moon's light to reach us and about 8 minutes for the Sun's radiation to visit us.

  • Large masses like the sun and other stars and galaxies bend light because of their mass.  The larger the mass, the more bending that occurs.

  • Albert Einstein predicted that certain confluences of giant galaxies might be used as a lens to see deeper into the past.  These would act  much like an ordinary magnifying glass

If you'd like to see an animation of this click here.

(next column)


Ordinary Magnifying Glass

As with many of Einstein's predictions, we are seeing this happen.  The caption on the picture above shows what we are seeing.  

This study was done by Dr. Bolton and a team of scientists.  Click here to see an animation of a gravitational lens

These studies help resolve some questions about the relationship of brightness of a cosmological object and its distance away from us and also help investigate things like the existence of dark matter.