Gravitational lensing in action: This illustration shows a phenomenon known as gravitational lensing, which is used by astronomers to study very distant and very faint galaxies. Note that the scale has been greatly exaggerated in this diagram. In reality, the distant galaxy is much further away and much smaller. Lensing clusters are clusters of elliptical galaxies whose gravity is so strong that they bend the light from the galaxies behind them. This produces distorted, and often multiple images of the background galaxy. But despite this distortion, gravitational lenses allow for greatly improved observations as the gravity bends the light’s path towards Hubble, amplifying the light and making otherwise invisible objects observable. A team of astronomers has used Abell 383, one such gravitational lens, to observe a distant galaxy whose light is resolved into two images by the cluster. The gravitational lensing effect means that astronomers have been able to determine fascinating insights about the galaxy that would not normally be visible even with Hubble or large ground-based telescopes. Among their discoveries is that the distant galaxy’s stars are very old, meaning that galaxies probably formed earlier in cosmic history than we first thought.

Name: Abell 383
Type: Early Universe : Galaxy : Type : Gravitationally LensedEarly Universe : Galaxy : Grouping : Cluster
Category: Illustrations
Distance: z=0.187 (redshift)
Release date: 12 April 2011, 15:00
Credit: NASA, ESA & L. Calçada

Wide field view of Abell 383 (ground-based image): This ground-based view shows the area of sky around the lensing cluster Abell 383. Lensing clusters are clusters of elliptical galaxies whose gravity is so strong that they distort and magnify the light from faraway galaxies behind them. This can be a useful tool for astronomers when they want to observe galaxies that are very distant and very faint, as the distortion from the lens is compensated by the greatly increased brightness.

Name: Abell 383
Type: Early Universe : Galaxy : Type : Gravitationally LensedEarly Universe : Galaxy : Grouping : Cluster
Category: Stars
Constellation: Eridanus
Distance: z=0.187 (redshift)
Release date: 12 April 2011, 15:00
Credit: ESA/Hubble & Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

A rose made of galaxies: This image of a pair of interacting galaxies called Arp 273 was released to celebrate the 21st anniversary of the launch of the NASA/ESA Hubble Space Telescope.The distorted shape of the larger of the two galaxies shows signs of tidal interactions with the smaller of the two. It is thought that the smaller galaxy has actually passed through the larger one.

Name: Arp 273
Type: Local Universe : Galaxy : Type : Interacting
Category: AnniversaryGalaxies
Constellation: Andromeda
Distance: 300 million light years
Release date: 20 April 2011, 15:00
Credit: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

Hubble image of the Meathook Galaxy: This close-up Hubble view of the Meathook Galaxy (NGC 2442) focuses on the more compact of its two asymmetric spiral arms as well as the central regions. The spiral arm was the location of a supernova that exploded in 1999. These Hubble observations were made in 2006 in order to study the aftermath of this supernova. Ground-based data from MPG/ESO 2.2-metre telescope were used to fill out parts of the edges of this image.

Name: NGC 2442, SN 1999ga
Type: Local Universe : Star : Evolutionary Stage : SupernovaLocal Universe : Galaxy : Type : Spiral
Category: Galaxies
Constellation: Volans
Distance: 55 million light years
Release date: 4 May 2011, 12:00
Credit: NASA, ESA

Wide-field view of the Meathook Galaxy: This picture of the Meathook Galaxy (NGC 2442) was taken by the Wide Field Imager on the MPG/ESO 2.2-metre telescope at La Silla, Chile. It shows a much broader view than the Hubble image, although less detailed. This view includes the whole galaxy and the surrounding sky, and clearly shows the asymmetric spiral arms. The longer of the two arms has intense star formation, which is visible here as a pink glow: this is due to the radiation of young stars ionising the gas they form from. The asymmetric shape and star formation are both thought to be caused by tidal disruptions from a near-miss with another galaxy at some point in its history

Name: NGC 2442
Type: Local Universe : Galaxy : Type : Spiral
Category: Galaxies
Constellation: Volans
Distance: 55 million light years
Release date: 4 May 2011, 12:00
Credit: ESO