December 27 – Discovery of Messier 92 (1777)

The small, densely packed globular cluster Messier 92 was discovered on this day in 1777, not by Charles Messier, but by Johann Elert Bode.  Messier didn’t spot it until 1781.

M92 (Photo courtesy of the Isaac Newton Group of Telescopes, La Palma)
M92 (Photo credit: the Isaac Newton Group of Telescopes, La Palma)

M92 is a barely-naked eye object of magnitude 6.4, located in the constellation of Hercules. It is one of the oldest and brightest globular clusters, though not as bright as its neighbour in Hercules, M13, and is about 27,000 light years from Earth.

Some of the stars in M92 are about 14 billion years old, making them roughly the same age as the Universe.  This established age probably led to lively debate among astronomers when the Hubble Constant was first used to put the age of the Universe at 12 billion years.