Galaxies Gone Wild!: These images show 6 different snapshots of galaxies at different stages of merging. It takes hundreds of millions of years for one merger to complete, so the individual stages are illustrated with different images from the fifty nine new images of colliding galaxies that make up the largest collection of Hubble images ever released together. As this astonishing Hubble atlas of interacting galaxies illustrates, galaxy collisions produce a remarkable variety of intricate structures. 1. Typically the first sign of an interaction will be a bridge of matter as the first gentle tugs of gravity tease out dust and gas from the approaching galaxies. 2. As the outer reaches of the galaxies begin to intermingle, long streamers of gas and dust, known as tidal tails, stretch out and sweep back to wrap around the cores. 3. These long, often spectacular, tidal tails are the signature of an interaction and can persist long after the main action is over. 4. As the galaxy cores approach each other their gas and dust clouds are buffeted and accelerated dramatically by the conflicting pull of matter from all directions. These forces can result in shockwaves rippling through the interstellar clouds. 5. Gas and dust are siphoned into the active central regions, fuelling bursts of star formation that appear as characteristic blue knots of young stars. As the clouds of dust build they are heated so that they radiate strongly, becoming some of the brightest infrared objects in the sky. 6. Some of the galaxies show striking, highly distorted features, with dust lanes crossing between the galaxies and long filaments of stars and gas extending far beyond the central regions. Beautifully interwoven galaxies are the twisted outcomes of these gargantuan encounters. These colossal and violent interactions between the galaxies, trigger star formation from the large clouds of gas in dazzling, dramatic bursts, creating brilliant blue star clusters. Most of the 59 new Hubble images are part of a large investigation of luminous and ultraluminous infrared galaxies called the GOALS project (Great Observatories All-sky LIRG Survey). This survey combines observations from Hubble, the NASA Spitzer Space Observatory, the NASA Chandra X-Ray Observatory and NASA Galaxy Explorer. The Hubble observations are led by Professor Aaron S. Evans from the University of Virginia and the National Radio Astronomy Observatory (USA).

Name: Merging Galaxies
Type: Local Universe : Galaxy : Type : Interacting
Category: AnniversaryGalaxies
Release date: 24 April 2008, 15:00
Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University), K. Noll (STScI), and J. Westphal (Caltech)

Arp 148: Arp 148 is the staggering aftermath of an encounter between two galaxies, resulting in a ring-shaped galaxy and a long-tailed companion. The collision between the two parent galaxies produced a shockwave effect that first drew matter into the centre and then caused it to propagate outwards in a ring. The elongated companion perpendicular to the ring suggests that Arp 148 is a unique snapshot of an ongoing collision. Infrared observations reveal a strong obscuration region that appears as a dark dust lane across the nucleus in optical light. Arp 148 is nicknamed "Mayall's object" and is located in the constellation of Ursa Major, the Great Bear, approximately 500 million light-years away. This interacting pair of galaxies is included in Arp's catalogue of peculiar galaxies as number 148. This image is part of a large  collection of 59 images of merging galaxies taken by the Hubble Space Telescope and released on the occasion of its 18th anniversary on 24th April 2008.

Name: Arp 148, Mayall's object
Type: Local Universe : Galaxy : Type : Interacting
Category: AnniversaryGalaxies
Constellation: Ursa Major
Distance: 450 million light years
Release date: 24 April 2008, 15:00
Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University), K. Noll (STScI), and J. Westphal (Caltech)

UGC 9618: Arp 302 consists of a pair of very gas-rich spiral galaxies in their early stages of interaction: VV 340A is seen edge-on to the left, and VV 340B face-on to the right. An enormous amount of infrared light is radiated by the gas from massive stars that are forming at a rate similar to the most vigorous giant star-forming regions in our own Milky Way. UGC 9618 is 450 million light-years away from Earth, and is the 302nd galaxy in Arp's Atlas of Peculiar Galaxies. This image is part of a large  collection of 59 images of merging galaxies taken by the Hubble Space Telescope and released on the occasion of its 18th anniversary on 24th April 2008.

Name: Arp 302, UGC 9618
Type: Local Universe : Galaxy : Type : Interacting
Category: AnniversaryGalaxies
Constellation: Bootes
Distance: 450 million light years
Release date: 24 April 2008, 15:00
Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)