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Messier 100
Messier 100
Credit: NASA, ESA

M100 (NGC 4321)

Messier 100 (NGC 4321) is a spiral galaxy located in the constellation Coma Berenices in the Virgo Cluster of galaxies. M100 is 55000000 light years away from Earth.

M100 is best viewed during late spring, is magnitude 9.5, and can be viewed with small telescope. M100 is 7.4' x 6.3' in apparent size. For reference, the full moon is 30'.

Observing difficulty: Hard

      1. Name:
      1. Type:
      2. spiral galaxy
      1. NGC or IC:
      2. NGC 4321
      1. Magnitude:
      2. 9.5
      1. Viewing:
      2. small telescope
      1. Size:
      2. 7.4' x 6.3'
      1. Distance (light years):
      2. 55000000 LY
      1. RA:
      2. 12h 23.0m
      1. Dec:
      2. 15 50'
      1. Season:
      2. late spring
      1. Galaxy group:
      2. Virgo Cluster

    * The naked eye can see up to magnitude ~7-8 objects under ideal dark sky conditions.

    A Grand Design in the Coma Berenices Constellation

    Messier 100 (M100) is a grand design spiral galaxy situated in the northern constellation Coma Berenices. First discovered by French astronomer Pierre M?chain on March 15, 1781, it was subsequently included in the catalogue of deep sky objects by Charles Messier, his colleague. Messier 100 belongs to the Virgo Cluster, a dense concentration of galaxies within the Virgo and Coma Berenices constellations, and is one of the brightest and largest galaxies within this cluster.

    Physical Characteristics of Messier 100

    Spanning about 7 arc minutes in diameter, or 120,000 light-years if you consider its actual size, Messier 100 is similar in size to our own Milky Way galaxy. The galaxy's grand design structure is characterized by prominent and well-defined spiral arms, where active star formation is readily observable. Additionally, Messier 100 is known to host two satellite galaxies, NGC 4323 and NGC 4328.

    The central region of Messier 100 is particularly fascinating, featuring a ring of star formation around a core, a phenomenon likely caused by density waves moving through the galaxy. There's also a supermassive black hole in the galaxy's core, roughly estimated to be 20 million times the mass of our Sun.

    Magnitude and Distance

    Messier 100 is located at a distance of approximately 55 million light-years from Earth. It has an apparent magnitude of 10.1, making it a relatively bright galaxy, though still not visible to the naked eye. In terms of absolute magnitude, M100 is considerably brighter than our own Milky Way galaxy, making it one of the most luminous galaxies in the Virgo Cluster.

    Finding and Observing Messier 100

    To locate Messier 100, observers should start by identifying the constellation of Coma Berenices, which becomes observable in the night sky from March to July. The galaxy is positioned near the North Galactic Pole, which is above the plane of our Milky Way and hence relatively free of our galaxy's obscuring dust.

    Although M100 is not visible to the naked eye, it can be viewed using a small to medium-sized telescope under dark sky conditions. The galaxy appears as a faint, circular patch of light with a brighter center. The spiral arms are challenging to discern without larger telescopes, but with larger apertures and clear skies, observers might catch a glimpse of the galaxy's intricate structure.

    The observation of M100 offers insights into the behavior of spiral galaxies, especially in terms of their structure and star formation. It serves as a window into our understanding of the universe, its past, present, and future.