Hubble's Universe Unfiltered

  • November 4, 2008

    Episode 2: Hubble Falls Into Coma

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    The Coma Cluster of Galaxies is one of the richest collections of galaxies in the nearby universe. Several thousand galaxies are gathered together by their mutual gravity, making it an ideal location for observing the full diversity of galaxies in the universe. While ground-based telescopes can record the wide-angle view, Hubble's keen eye captures the details of not only spirals and ellipticals in the cluster, but also galaxies a billion light-years beyond. Join us, as we journey into the Coma Cluster and explore its rich landscape of galaxies.

    • Johannes Hevelius' drawings of the Boötes, Coma Berenices, and Corona constellations are actually backward from the way we see the constellations in the sky. Back in the day, constellation figures were drawn on the outside of a sphere, with the Earth located at the center of the sphere. Hence, the artist would have to flip the locations of the stars to present the correct orientation. The constellations on the ceiling of Grand Central Station in New York City used a similar ancient source. Thus, thousands of commuters look up each day and see the constellations backward.

    • The Coma Cluster contains several thousand galaxies, has a diameter of roughly 15 million light-years, and is located about 300 million light-years away. Contrast that with our Local Group of galaxies, which has only two large galaxies, one medium-sized galaxy, and about three dozen small galaxies. The Local Group covers perhaps 3 million light-years. You can see that our Milky Way Galaxy does not live in one of the big cities of the universe. We are located in more of a small town, as galaxy collections go.

    • The nearest large cluster of galaxies is the Virgo Cluster. It is about 50 million light-years away and contains a couple thousand galaxies. At this distance, however, we're actually too close to get a good look. The galaxies of Virgo appear to us to be spread across a large swath of the sky, tens of degrees wide. Hence, when we look at pictures of the Virgo Cluster, we don't see the dense collection of galaxies that it really is. It's like we can see the trees well, but don't get a good view of the whole forest.

    • The movie that zooms into the Coma Cluster starts with a view that is about 20 degrees wide and ends with a view about one arc minute wide. Since there are 60 arc minutes in a degree, that makes for about a 1200x zoom. For comparison, most cameras have less than a 10x zoom. To accomplish this extreme zoom, the animator used several different images at different resolutions and cross-faded between them during the zoom.

    Image notes

    Coma Berenices Constellation
    Credit: A. Fujii

    Gold Octadrachm Issued by Ptolemy III
    Credit: Marie-Lan Nguyen and British Museum, London, United Kingdom

    Bust of Queen Berenice II
    Credit: Bibi Saint-Pol and Glyptothek, Munich, Germany

    Constellations Boötes, Coma Berenices, and Corona
    Credit: Johannes Hevelius, Uranographia, 1690

    Wide-Field Image of the Coma Cluster of Galaxies
    Credit: ESA/Hubble and Digitized Sky Survey
    Acknowledgement: D. De Martin

    Hubble Image of the Coma Cluster of Galaxies
    Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
    Acknowledgment: D. Carter (Liverpool John Moores University) and the Coma HST ACS Treasury Team

    Zoom Into the Coma Cluster of Galaxies
    Credit: NASA, ESA, and G. Bacon (STScI)