The Changing Face of Comet 67P

A 30-m wide boulder with a mass of almost 13,000 tonnes was found to have moved about 140 m across the face of Comet 67P/Churyumov–Gerasimenko in the months before the comet reached perihelion in August, 2015. That was when the when the comet’s activity was at its highest. In both images above, an arrow points to the boulder; in the right-hand image, the dotted circle outlines the original location of the boulder for reference. The rock was probably moved by jets of material outgassing from the comet.

Image Credit: ESA

The Orion Nebula in False Color

This false color image of the Orion Nebula was generated using visible light and infrared data from two of the instruments onboard the Hubble Space Telescope. The image shows a segment of the sky about 0.002° wide. That works out to around 3.4 light-years at the nebula which is 1,500 light-years away.

Image Credit: Nasa / ESA / STScI

Messier 106

Messier 106 also known as NGC 4258 is an intermediate spiral galaxy about 22 to 25 million light-years away from Earth. It is also a Seyfert II galaxy. X-rays and unusual emission lines have been detected coming from M106, leading astronomers to suspect that part of the galaxy is falling into a supermassive black hole in the center. A Type II supernova was observed in this galaxy in May, 2014. A Type II supernova is caused by a the rapid collapse and subsequent violent explosion of a massive star.

Image Credit: NASA / ESA

The Fireworks Galaxy

NGC 6946 is known as the Fireworks Galaxy, In the past century, nine supernovae have been observed to explode in its spiral arms. This makes it the most prolific known galaxy for this type of event over a period of 100 years. By comparison, the Milky Way galaxy, which has twice as many stars as NGC 6946, averages one supernova event per century.

Image Credits: NASA, ESA, STScI, R. Gendler, and the Subaru Telescope (NAOJ)

Westerlund 1

This is a young super star cluster known as Westerlund 1. It’s the home of one of the largest stars yet found. Westerlund 1-26 is a red supergiant with a radius over 1,500 times that of our sun. Indeed, it’s sometimes referred to as a hypergiant star. If Westerlund 1-26 were at the center of our solar system, it would extend out beyond the orbit of Jupiter.

The Westerlund 1 cluster is relatively young in astronomical terms, around three million years old. The Sun is around 4.6 billion years old.

Image Credit: NASA / ESA