Microlensing of the Einstein Cross
Credit & Copyright: G. Lewis (IOA),
M. Irwin (RGO), William
Hershel Telescope
Explanation:
The famous "Einstein Cross" is a
case where a single object is seen four times. Here a very distant
QSO happened to be placed right behind
a
massive galaxy. The gravitational
effect of the galaxy on the distant QSO
was similar to the lens effect of an empty wine glass on a distant
street light - it created multiple images. But stars in the foreground
galaxy have been found to act as
gravitational lenses
here too! These stars make the images change brightness relative
to each other. These brightness changes are visible on these two
photographs of the
Einstein Cross,
taken about 3 years apart.
Authors & editors:
Robert Nemiroff
(MTU) &
Jerry Bonnell
(USRA)
NASA Web Site Statements, Warnings,
and Disclaimers
NASA Official: Jay Norris.
Specific
rights apply.
A service of:
LHEA at
NASA /
GSFC
& Michigan Tech. U.
