NASA Astronomy Picture of the Day Collection

Abell 2218: A Galaxy Cluster Lens

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';

Andrew Fruchter [ http://www.stsci.ed…] (STScI [ http://www.stsci.ed…]) et al., WFPC2 [ http://www.stsci.ed…], HST [ http://www.stsci.ed…], NASA [ http://www.nasa.gov/]

Arizona

Virginia

Goddard Space Flight Center (GSFC)

Draco

Hubble Space Telescope (HST)

http://antwrp.gsfc.…

SPD-APOD-ap080210