Mark Anderson may refer to:
Rear Admiral Mark Anderson CB is a former Royal Navy officer who served as Commander Operations and Rear Admiral, Submarines.
Naval career
Educated at the University of Manchester, Anderson joined the Royal Navy in 1974 and was appointed commanding officer of the submarine HMS Talent in 1993. He became Military Assistant to the Chief of Defence Logistics in May 2000, Commanding Officer of the frigate HMS Marlborough as well as Captain of the 4th Frigate Squadron in August 2002 and Director Equipment Capability (Underwater Effects) in March 2003 before moving on to become the Chief of the Defence Staff's Liaison Officer to the U.S. Joint Chiefs of Staff Committee in July 2007 and Commander Operations and Rear Admiral, Submarines in January 2009. He retired from the Royal Navy in March 2011.
In retirement he became Strategy Director of Sonar & Undersea Systems and then Group Marketing Director at Ultra Electronics.
References
Mark Anderson (born 16 November 1991) is a male Belizean sprinter. He competed in the Men's 100 metres event at the 2015 World Championships in Athletics in Beijing, China.
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A dark galaxy is a hypothesized galaxy with no, or very few, stars. They received their name because they have no visible stars, but may be detectable if they contain significant amounts of gas. Astronomers have long theorized the existence of dark galaxies, but there are no confirmed dark galaxies to date. Dark galaxies are distinct from intergalactic gas clouds caused by galactic tidal interactions, since these gas clouds do not contain dark matter, so they do not technically qualify as galaxies. Distinguishing between intergalactic gas clouds and galaxies is difficult; most candidate dark galaxies turn out to be tidal gas clouds. The best candidate dark galaxies to date include HI1225+01, AGC229385, and numerous gas clouds detected in studies of quasars.
Observational evidence
Large surveys with sensitive, but low resolution radio telescopes like Arecibo or the Parkes Telescope look for 21 cm emission from atomic hydrogen in galaxies. These surveys are then matched to optical surveys to identify any objects with no optical counterpart, i.e. sources with no stars. However, significant follow-up observations are required to show they have detected a dark galaxy. Astronomers need to demonstrate that the gas is rotating like a galaxy (due to the gravitational influence of dark matter), and that the galaxy actually doesn't have any stars.