Blue Stragglers


This animation is an artist’s rendering of the movement of blue straggler stars in a globular cluster over time. Blue straggler stars are blue, bright stars with a higher-than-average mass for a cluster. Over time, they sink toward the center of a star cluster. Those closest to the cluster core are the first to migrate inwards; more distant blue stragglers move inward over time.

Video Credit: ESA

Messier 13


Messier 13 is a large globular star cluster about 25,000 light years from Earth. It contains several hundred thousand stars and is about 145 light-years in diameter. July is a good month to look for it with a pair of binoculars. About a-third of the way from Vega to Arcturus, four bright stars in the constellation of Hercules form the Keystone asterism. M13 can be seen partway between Zeta Herculis and Eta Herculis, the two star that form the shoulders of the constellation.

Image Credit: NASA / ESA

Messier 56


Messier 56 (or M56) is a globular cluster in the constellation Lyra. It appears to be a slightly fuzzy star in large binoculars or a small telescope, but the cluster can be resolved using a telescope with an aperture of 20 cm or larger.

M56 is at a distance of about 32,900 light-years from Earth and measures around 84 light-years across, with a combined mass some 230,000[4] times that of the Sun. Because the cluster appears to be 13.7 billion years and is following a retrograde orbit through the Milky Way, it is believed to be part of the Gaia Sausage, the remains of a dwarf galaxy that merged with the Milky Way.

Image Credit: NASA / ESA

Messier 75


This is Messier 75. It’s a globular cluster, a spherical collection of stars bound together by gravity. It’s around 67,000 light-years away. The majority of the cluster’s 400,000 stars are in its core, making it is one of the most densely packed clusters ever found. It’s extremely bright,180,000 times brighter than the Sun.

Image Credit: NASA / ESA