Gravity can bend light, allowing huge clusters of galaxies to act as telescopes. Almost all of the bright objects in this Hubble Space Telescope [
http://antwrp.gsfc.
] image are galaxies in the cluster [
http://antwrp.gsfc.
of galaxies" ] known as Abell 2218. The cluster [
http://adc.gsfc.nas
] is so massive and so compact that its gravity bends and focuses the light [
http://en.wikipedia
] from galaxies that lie behind it. As a result, multiple images [
http://antwrp.gsfc.
] of these background galaxies are distorted into long faint arcs -- a simple lensing effect analogous to viewing distant street lamps through a glass of wine [
http://www.upenn.ed
]. The cluster of galaxies [
http://www.seds.org
] Abell 2218 is itself about three billion light-years [
http://chandra.harv
] away in the northern constellation of the Dragon (Draco [
http://www.seds.org
]). The power of this massive cluster telescope has allowed astronomers [
http://oposite.stsc
] to detect a galaxy at redshift [
http://www.astro.vi
] 5.58, the most distant galaxy [
http://antwrp.gsfc.
] yet measured. This young, still-maturing galaxy is faintly visible to the lower right of the cluster core.
digg_url = 'http://apod.nasa.go v/apod/ap080210.html '; digg_skin = 'compact';
Explanation
Gravity can bend light, allowing huge clusters of galaxies to act as telescopes. Almost all of the bright objects in this Hubble Space Telescope [
http://antwrp.gsfc.
] image are galaxies in the cluster [
http://antwrp.gsfc.
of galaxies" ] known as Abell 2218. The cluster [
http://adc.gsfc.nas
] is so massive and so compact that its gravity bends and focuses the light [
http://en.wikipedia
] from galaxies that lie behind it. As a result, multiple images [
http://antwrp.gsfc.
] of these background galaxies are distorted into long faint arcs -- a simple lensing effect analogous to viewing distant street lamps through a glass of wine [
http://www.upenn.ed
]. The cluster of galaxies [
http://www.seds.org
] Abell 2218 is itself about three billion light-years [
http://chandra.harv
] away in the northern constellation of the Dragon (Draco [
http://www.seds.org
]). The power of this massive cluster telescope has allowed astronomers [
http://oposite.stsc
] to detect a galaxy at redshift [
http://www.astro.vi
] 5.58, the most distant galaxy [
http://antwrp.gsfc.
] yet measured. This young, still-maturing galaxy is faintly visible to the lower right of the cluster core.
digg_url = 'http://apod.nasa.go v/apod/ap080210.html '; digg_skin = 'compact';
Explanation