Messier 92 is one of the brightest globular clusters in the northern sky, but it is often overlooked by amateur astronomers because of its proximity to the even more spectacular Messier 13. It is visible to the naked eye under very good seeing conditions. Indeed, M92 is among the brightest clusters in terms of absolute magnitude as well as being one of the oldest clusters in the Milky Way.

Image Credit: ESA / NASA

NGC 4858

Within the boundary of the constellation Coma Berenices (Berenice’s Hair) lies the impressive Coma Cluster. It’s a group of over a thousand galaxies bound together by gravity. Many of these galaxies are elliptical. The brighter of the two galaxies that stand out in this image is NGC 4860, an example of an elliptical galaxy. The other bright galaxy in the picture is NGC 4858 can be seen to the left of its brighter neighbor and stands out because of of its unusual, tangled, fiery appearance. NGC 4858 isn’t a simple spiral; it’s something called a “galaxy aggregate.” As the name suggests, it’s made up of a central galaxy surrounded by a handful of luminous knots of material that seem to stem from it, altering its overall structure. NGC 4858 is experiencing an extremely high rate of star formation, making new stars so frantically that it will use up all of its gas long before it reaches the end of its life. The red color of its bright knots indicates that they are formed of hydrogen, which glows in various shades of bright red when it is energized by stellar radiation.

Image Credit: ESA / NASA

Abell 370

This Hubble image contains around 8,000 galaxies. It’s centered on a galaxy cluster known as Abell 370 which contains several hundred massive galaxies. The cluster is about 4 billion light-years away, and it’s huge mass functions as a gravitational lens which distorts the light coming from galaxies behind it.

Image Credit: ESA / NASA

Monster Stars

R136 observed with WFC3This Hubble image shows the central region of the Tarantula Nebula in the Large Magellanic Cloud. The young and dense star cluster R136 can be seen the lower right of the image. This cluster contains hundreds of young blue stars. One of them is the most massive star detected in the universe to date.

Dozens of stars in the cluster exceed 50 solar masses, and nine very massive stars are all more than 100 times more massive than the Sun. The most massive is R136a1—weighing in at more than 250 solar masses.

Image Credit: NASA / ESA