Hubble and Spitzer Uncover Smallest Galaxy Building Blocks: In this image of the Hubble Ultra Deep Field, several objects are identified as the faintest, most compact galaxies ever observed in the distant Universe. They are so far away that we see them as they looked less than one billion years after the Big Bang. Blazing with the brilliance of millions of stars, each of the newly discovered galaxies is a hundred to a thousand times smaller than our Milky Way Galaxy. The bottom row of pictures shows several of these clumps (distance expressed in redshift value). Three of the galaxies appear to be slightly disrupted. Rather than being shaped like rounded blobs, they appear stretched into tadpole-like shapes. This is a sign that they may be interacting and merging with neighboring galaxies to form larger structures. The detection required joint observations between Hubble and NASA's Spitzer Space Telescope. Blue light seen by Hubble shows the presence of young stars. The absence of red light from Spitzer observations conclusively shows that these are truly young galaxies without an earlier generation of stars.

Name: Hubble Ultra Deep Field, HUDF
Type: Early Universe : Galaxy : Grouping : Cluster
Category: Galaxies
Release date: 6 September 2007, 18:00
Credit: NASA, ESA, and N. Pirzkal (European Space Agency/STScI)

Hubble Ultra Deep Field: The Hubble Ultra Deep Field Image.

Name: Hubble Ultra Deep Field, HUDF
Type: Early Universe : Galaxy : Grouping : Cluster
Category: Galaxies
Constellation: Fornax
Release date: 6 September 2007, 18:00
Credit: NASA, ESA, and N. Pirzkal (European Space Agency/STScI) and the HUDF Team (STScI)

Extreme star cluster bursts into life in new Hubble image: The star-forming region NGC 3603 - seen here in the latest Hubble Space Telescope image - contains one of the most impressive massive young star clusters in the Milky Way. Bathed in gas and dust the cluster formed in a huge rush of star formation thought to have occurred around a million years ago. The hot blue stars at the core are responsible for carving out a huge cavity in the gas seen to the right of the star cluster in NGC 3603's centre.

Name: NGC 3603
Type: Milky Way : Star : Grouping : Cluster : Open
Category: NebulaeStar Clusters
Constellation: Carina
Distance: 20000 light years
Release date: 2 October 2007, 15:00
Credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

Extreme star cluster bursts into life in new Hubble image: An annotated version of the above Hubble image. The enormous cavity blown out by the young stars in the massive star cluster in NGC 3603's centre can be seen to the right of the cluster. Of particular interest is the lower left of the image. This is darker due to a mix of extinction of starlight and interstellar reddening caused by foreground dust clouds. Giant pillars of gas can also be seen extending away from the central cluster whilst the striking Bok Globules reside, silhouetted against the nebula, at the top right of the image.

Name: NGC 3603
Type: Milky Way : Star : Grouping : Cluster : Open
Category: Star Clusters
Distance: 20000 light years
Release date: 2 October 2007, 15:00
Credit: NASA, ESA and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration

Extreme star cluster bursts into life (ground-based image): A wide-field image in the region of NGC 3603 taken on the ground by the Digitized Sky Survey 2. The glowing clouds of hydrogen gas (seen here in orange) compose a vast emission nebula. The field of view is approximately 2.6 x 2.8 degrees.

Name: NGC 3603
Type: Milky Way : Star : Grouping : Cluster : Open
Category: Nebulae
Constellation: Carina
Distance: 20000 light years
Release date: 2 October 2007, 15:00
Credit: NASA, ESA, and the Digitized Sky Survey 2. Acknowledgment: Davide De Martin (ESA/Hubble)

Extreme star cluster bursts into life  (ground-based image): A wide-field image of the Milky Way stretching across the southern sky. The beautiful Carina Nebula (NGC 3372) is seen at the right of the image glowing in red. It is within this spiral arm of our Milky Way that NGC 3603 resides. At the centre of the image is the constellation of the Southern Cross. The bright yellow/white star at the left of the image is alpha Centauri, in fact a system of three stars, at a distance of about 4.4 light-years from Earth.

Type: Solar System : Sky Phenomenon : Night Sky : Milky Way
Category: Stars
Release date: 2 October 2007, 15:00
Credit: A. Fujii

Hubble Finds Mature Galaxy Masquerading as Toddler: The NASA/ESA Hubble Space Telescope quashed the possibility that what was previously believed to be a toddler galaxy in the nearby universe may actually be considered an adult. Called I Zwicky 18, this galaxy has a youthful appearance that resembles galaxies typically found only in the early universe. Hubble has now found faint, older stars within this galaxy, suggesting that the galaxy may have formed at the same time as most other galaxies. I Zwicky 18 is classified as a dwarf irregular galaxy and is much smaller than our Milky Way Galaxy. The concentrated bluish-white knots embedded in the heart of the galaxy are two major starburst regions where stars are forming at a furious rate. The wispy blue filaments surrounding the central starburst regions are bubbles of gas that have been blown away by stellar winds and supernovae explosions from a previous generation of hot, young stars. This gas is now heated by intense ultraviolet radiation unleashed by hot, young stars. A companion galaxy lies just above and to the left of I Zwicky 18. The companion may be interacting with I Zwicky 18 by gravitationally tugging on the galaxy. The interaction may have triggered the galaxy's recent star formation that is responsible for the youthful appearance. Besides the bluish-white young stars, white-reddish stars also are visible in both I Zwicky 18 and its companion. These stars may be as old as 10 billion years. The reddish extended objects surrounding I Zwicky 18 and its companion are ancient, fully formed galaxies of different shapes that are much farther away. Hubble data also allowed astronomers for the first time to identify Cepheid variable stars in I Zwicky 18. These flashing stellar mile-markers were used to determine that I Zwicky 18 is 59 million light-years from Earth, almost 10 million light-years more distant than previously believed. The observations of I Zwicky 18 were taken in 2005 and 2006 with Hubble's Advanced Camera for Surveys. Astronomers made this image by combining observations taken with blue and red filters. The science team consists of Alessandra Aloisi and Marco Sirianni of the European Space Agency and Space Telescope Science Institute; Francesca Annibali,Jennifer Mack, and Roeland van der Marel of the Space Telescope Science Institute; Abhijit Saha of the National Optical Astronomy Observatories; and Gisella Clementini, Rodrigo Contreras, Giuliana Fiorentino, Marcella Marconi, Ilaria Musella, and Monica Tosi of the Italian National Astrophysics Institutes in Bologna and Naples.

Name: I Zw 18
Type: Local Universe : Galaxy : Type : IrregularLocal Universe : Galaxy : Size : Dwarf
Category: Galaxies
Constellation: Ursa Major
Distance: 60 million light years
Release date: 16 October 2007, 16:00
Credit: NASA, ESA, and A. Aloisi (European Space Agency and Space Telescope Science Institute)