Messier 66 is an intermediate spiral galaxy

Intermediate spiral galaxy

An intermediate spiral galaxy is a galaxy that is in between the classifications of a barred spiral galaxy and an unbarred spiral galaxy. It is designated as SAB in the galaxy morphological classification scheme.-Grades:...

 about 36 million light-year

Light-year

A light-year, also light year or lightyear is a unit of length, equal to just under 10 trillion kilometres...

s away in the constellation

Constellation

In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....

 Leo

Leo (constellation)

Leo is one of the constellations of the zodiac. Its name is Latin for lion. Its symbol is . Leo lies between dim Cancer to the west and Virgo to the east.-Stars:...

. It was discovered by Charles Messier

Charles Messier

Charles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of deep sky objects such as nebulae and star clusters that came to be known as the 110 "Messier objects"...

 in 1780. M66 is about 95 thousand light-years across with striking dust lanes and bright star clusters along sweeping spiral arms.
M66 is part of the famous Leo Triplet

Leo Triplet

The Leo Triplet is a small group of galaxies about 35 million light-years away in the constellation Leo. This galaxy group consists of the spiral galaxies M65, the M66, and the NGC 3628.-Members:...

, a small group of galaxies that also includes M65

Messier 65

Messier 65 is an intermediate spiral galaxy about 35 million light-years away in the constellation Leo. It was discovered by Charles Messier in 1780. M65, M66, and NGC 3628 comprise the famous Leo Triplet, a small group of galaxies.-Discovery:M65 was discovered by Charles Messier and included in...

 and NGC 3628

NGC 3628

NGC 3628, also known as Sarah's Galaxy, is an unbarred spiral galaxy about 35 million light-years away in the constellation Leo. It was discovered by William Herschel in 1784. It has an approximately 300,000 light-years long tidal tail. NGC 3628 along with M65 and M66 form the famous Leo...

.

History

Gravitational interaction from its past encounter with neighboring NGC 3628 has resulted in:

• An extremely high central mass concentration;
• A high molecular
  Molecular mass
  The molecular mass of a substance is the mass of one molecule of that substance, in unified atomic mass unit u...
  
   to atomic mass
  Atomic mass
  The atomic mass is the mass of a specific isotope, most often expressed in unified atomic mass units. The atomic mass is the total mass of protons, neutrons and electrons in a single atom....
  
   ratio;
• A resolved noncorotating clump of H I material apparently removed from one of the spiral arms.

This third result shows up visually as an extremely prominent and unusual spiral arm and dust lane structures as originally noted in the Atlas of Peculiar Galaxies

Atlas of Peculiar Galaxies

The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institute of Technology....

.

External links

• SEDS: Spiral Galaxy M66
• Spiral Galaxy M66
• Astronomy Picture of the Day
  Astronomy Picture of the Day
  Astronomy Picture of the Day is a website provided by NASA and Michigan Technological University . According to the website, "Each day a different image or photograph of our universe is featured, along with a brief explanation written by a professional astronomer."The photograph is not necessarily...
  
  - Unusual Spiral Galaxy M66 from Hubble - 2010 April 13