About the Background Image
This image was
taken with the Hubble Space Telescope on July 29, 1999,
as part of an ongoing investigation of colliding galaxies.
This project is being carried out by myself and several collaborators,
and aims to unravel some of the mysteries of
colliding galaxies in distant parts of the universe
(please see
HST Snapshot Survey of
CNOC2 Pairs for more information).
In the following section, I describe several of the
phenomena seen in this image.
Distant Galaxies
This is an example of a distant galaxy as seen by the
Hubble Space Telescope (HST). This galaxy lies at a distance
of approximately 2 billion light years (about
20,000,000,000,000,000,000,000 kilometres!).
We are seeing this galaxy as it was 2 billion years ago.
A Major Merger
This is an example of a collision between two galaxies
of roughly equal size. An event such as this, known as
a major merger, is thought to result in the formation of a single
elliptical galaxy.
A Minor Merger?
This image may show the early stages of the accretion
of a dwarf galaxy onto a large elliptical galaxy.
The presence of a dark dust lane running through the
elliptical galaxy, along with signs of shell-like
debris nearby, provides circumstantial evidence that
this galaxy has had a recent close encounter with another
galaxy.
Stars in the Milky Way
Several stars are also visible, and can easily be
distinguished by cross-like diffraction spikes.
These stars are located in our own galaxy,
the Milky Way. These stars are much closer
to us than any of the galaxies seen in this image.