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M101 Pinwheel Galaxy
Magnitude: 7.86
Distance: Aprox: 21 million light-years
Constellation: Ursa Major
Diameter: 170,000 light-years
Number of Stars Approx: 1 Trillion
The Pinwheel Galaxy galaxy is quite large, but has a low surface brightness and requires exceptionally clear, moonless skies to be seen, even in medium-sized telescopes. Messier 101 is easy to find because it is located just above the handle of the Big Dipper. It forms a triangle with Alkaid and the double star Mizar/Alcor. The best time of year to observe the Pinwheel Galaxy is during the spring.
The Pinwheel Galaxy appears symmetric in images that only reveal its central region, but is really quite asymmetrical as a result of interactions with smaller companion galaxies. The galaxy’s core is displaced from the centre, likely as a result of a collision in the recent past.
M101 has five prominent companions: NGC 5204, NGC 5474, NGC 5477, NGC 5585 and Holmberg IV. Gravitational interaction with these galaxies is suspected to have triggered the formation of the grand design structure in M101 and distorted NGC 5474.
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NGC 5474 dwarf spiral galaxy
Magnitude: 11.3
Distance: Aprox: 22.1 million light-years
Constellation: Ursa Major
Among the Pinwheel Galaxy's companions, NGC 5474 galaxy is the closest to the Pinwheel Galaxy itself. The gravitational interaction between NGC 5474 and the Pinwheel Galaxy has strongly distorted the former. NGC 5474 shows some signs of a spiral structure. As a result, this galaxy is often classified as a dwarf spiral galaxy, a relatively rare group of dwarf galaxies.
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NGC 5477 dwarf galaxy
Magnitude: 14.01
Distance: Aprox: 20 million light-years
Constellation: Ursa Major
Taken 4/21/18 in Toledo Ohio by Russell Kille on a CPC 1100 with Hyperstar @ F2 and ZWO ASI294MC Pro camera
Taken 5/24/19 in Grand Rapids Ohio by Russell Kille on a CPC 1100 with Hyperstar @ F2 and ZWO ASI294MC Pro camera
