Wide-field view of Abell 2744 (ground-based image): This ground-based view shows the area of sky around the merging galaxy cluster Abell 2744, which has been given the nickname Pandora’s Cluster. This remarkable object seems to be the result of the collision of at least four separate galaxy clusters. In this picture the cluster itself is faintly visible as a tiny swarm of faint specks very close to the centre.

Name: Abell 2744
Type: Early Universe : Galaxy : Grouping : Cluster
Category: Cosmology
Constellation: Sculptor
Distance: z=0.308 (redshift)
Release date: 22 June 2011, 15:00
Credit: ESA/Hubble & Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

Stars in the Andromeda Galaxy’s disc: This image shows NASA/ESA Hubble Space Telescope images of a small part of the disc of the Andromeda Galaxy, the closest spiral galaxy to the Milky Way. Hubble’s position above the distorting effect of the atmosphere, combined with the galaxy’s relative proximity, means that the galaxy can be resolved into individual stars, rather than the cloudy white wisps usually seen in observations of galaxies. A galaxy’s disc is the area made up of its spiral arms, and the darker areas between them. After the galaxy’s central bulge, this is the densest part of a galaxy. However, these observations are made near the edge, where the star fields are noticeably less crowded. This lets us see glimpses through the galaxy into the distant background, where the more diffuse blobs of light are actually faraway galaxies. These observations were made in order to observe a wide variety of stars in Andromeda, ranging from faint main sequence stars like our own Sun, to the much brighter RR Lyrae stars, which are a type of variable star. With these measurements, astronomers can determine the chemistry and ages of the stars in each part of the Andromeda Galaxy.

Name: Andromeda Galaxy, Messier 31
Type: Local Universe : Galaxy : Type : SpiralLocal Universe : Star : Type : VariableLocal Universe : Galaxy : Component : Disk
Category: GalaxiesStars
Constellation: Andromeda
Distance: 2 million light years
Release date: 21 July 2011, 10:00
Credit: NASA, ESA and T.M. Brown (STScI)

Stars in the Andromeda Galaxy’s giant stellar stream: This image shows NASA/ESA Hubble Space Telescope images of a small part of the giant stellar stream of the Andromeda Galaxy. The stream is a long structure thought to be the remains of a companion galaxy torn apart by the Andromeda Galaxy’s gravity and engulfed in it. Hubble’s position above the distorting effect of the atmosphere, combined with the galaxy’s relative proximity, means that this image can be resolved into individual stars, rather than the cloudy white wisps usually seen in observations of galaxies. These observations were made in order to observe a wide variety of stars in Andromeda, ranging from faint main sequence stars like our own Sun, to the much brighter RR Lyrae stars, which are a type of variable star. With these measurements, astronomers can determine the chemistry and ages of the stars in each part of the Andromeda Galaxy.

Name: Andromeda Galaxy, M 31, Messier 31
Type: Local Universe : Star : Type : VariableLocal Universe : Galaxy : Type : Spiral
Category: Stars
Constellation: Andromeda
Distance: 2 million light years
Release date: 21 July 2011, 10:00
Credit: NASA, ESA and T.M. Brown (STScI)

Stars in the Andromeda Galaxy’s halo with background galaxies (1): This image shows NASA/ESA Hubble Space Telescope images of a small part of the halo of the Andromeda Galaxy. The halo is the huge and sparse sphere of stars that surrounds a galaxy. While there are relatively few stars in a galaxy’s halo, studies of the rotation rate of galaxies suggest that there is a great deal of invisible dark matter here. Hubble’s position above the distorting effect of the atmosphere, combined with the galaxy’s relative proximity, means that this image can be resolved into individual stars, rather than the cloudy white wisps usually seen in observations of galaxies. In the background, many faraway galaxies are visible, billions of light-years further away than the Andromeda Galaxy. These observations were made in order to observe a wide variety of stars in Andromeda, ranging from faint main sequence stars like our own Sun, to the much brighter RR Lyrae stars, which are a type of variable star. With these measurements, astronomers can determine the chemistry and ages of the stars in each part of the Andromeda Galaxy.

Name: Andromeda Galaxy, M 31, Messier 31
Type: Local Universe : Star : Type : VariableLocal Universe : Galaxy : Component : HaloEarly Universe : Galaxy : Type : Spiral
Category: Stars
Constellation: Andromeda
Distance: 2 million light years
Release date: 21 July 2011, 10:00
Credit: NASA, ESA and T.M. Brown (STScI)

Stars in the Andromeda Galaxy’s halo with background galaxies (2): This image shows NASA/ESA Hubble Space Telescope images of a small part of the halo of the Andromeda Galaxy. The halo is the huge and sparse sphere of stars that surrounds a galaxy. While there are relatively few stars in a galaxy’s halo, studies of the rotation rate of galaxies suggest that there is a great deal of invisible dark matter here. Hubble’s position above the distorting effect of the atmosphere, combined with the galaxy’s relative proximity, means that this image can be resolved into individual stars, rather than the cloudy white wisps usually seen in observations of galaxies. In the background, many faraway galaxies are visible, billions of light-years further away than the Andromeda Galaxy. These observations were made in order to observe a wide variety of stars in Andromeda, ranging from faint main sequence stars like our own Sun, to the much brighter RR Lyrae stars, which are a type of variable star. With these measurements, astronomers can determine the chemistry and ages of the stars in each part of the Andromeda Galaxy.

Name: Andromeda Galaxy, M 31, Messier 31
Type: Local Universe : Galaxy : Type : SpiralLocal Universe : Galaxy : Component : Halo
Category: Stars
Constellation: Andromeda
Distance: 2 million light years
Release date: 21 July 2011, 10:00
Credit: NASA, ESA and T.M. Brown (STScI)