Who would have expected the Hubble Space Telescope (often referred to as HST or Hubble) to still be in operation after being launched into low Earth orbit in 1990? So, NASA/ESA kickstarted its 30th anniversary with some majestic galactic photos.
Five Space Shuttle missions have repaired, upgraded, and replaced systems on the telescope, including all five of the main instruments. … The fifth servicing mission … was completed in 2009.
heic2002 – Photo Release > Hubble Surveys Gigantic Galaxy (6 January 2020)
To kickstart the 30th anniversary year of the NASA/ESA Hubble Space Telescope, Hubble has imaged a majestic spiral galaxy. Galaxy UGC 2885 may be the largest known in the local universe. It is 2.5 times wider than our Milky Way and contains 10 times as many stars.
See also: EarthSky.org > “New Hubble view of gigantic galaxy” posted by Eleanor Imster and Deborah Byrd (January 13, 2020)
UGC 2885 is one of the spiral galaxies studied by the famous astronomer Vera Rubin (1928–2016) in her groundbreaking research in the 1970s. … She and astronomer Kent Ford examined more than 60 spiral galaxies. They found, in every case, that stars on the outer edges of galaxies revolved around the galaxies’ centers at least as fast as those in the inner regions. That observed fact ran counter to Kepler’s Laws of Motion, formulated in the early 1600s. Kepler’s insights suggested that stars in a galaxy’s outer regions should be moving more slowly than those in its inner regions, just as the outer planets in our solar system move more slowly than the inner planets.
Astronmomers reached a dramatic conclusion about Rubin and Ford’s findings: these galaxies contain mass we cannot see. This missing mass today is called dark matter.
HST > An Active Centre
Update April 3, 2020: YouTube > NASA Goddard > “The Hubble Space Telescope Virtual (360°) Tour” (Mar 30, 2020)