This Hubble image shows the lenticular galaxy Markarian 820, also known as Mrk 820. It lies in the constellation Boötes, about 300 million light-years from Earth. Image credit: ESA/Hubble & NASA and N. Grogin (STScI), Acknowledgement: Judy Schmidt.This galaxy is known as Mrk 820 and is classified as a lenticular galaxy — type S0 on the Hubble Tuning Fork. The Hubble Tuning Fork is used to classify galaxies according to their morphology. Elliptical galaxies look like smooth blobs in the sky and lie on the handle of the fork. They are arranged along the handle based on how elliptical they are, with the more spherical galaxies furthest from the tines of the fork, and the more egg-shaped ones closest to the end of the handle where it divides. The two prongs of the tuning fork represent types of unbarred and barred spiral galaxies.American astronomer Edwin Hubble developed a classification scheme of galaxies in 1926. Although this scheme, also known as the Hubble Tuning Fork diagram, is now considered somewhat too simple, the basic ideas still hold. The diagram is roughly divided into two parts: elliptical galaxies (ellipticals) and spiral galaxies (spirals). “S0,” or lenticular galaxies such as Mrk 820 are in the transition zones between ellipticals and spirals and bridge these two types. Image credit: NASA & ESA.Lenticular galaxies like Mrk 820 are in the transition zone between ellipticals and spirals and lie right where the fork divides. A closer look at the appearance of Mrk 820 reveals hints of a spiral structure embedded in a circular halo of stars.
Surrounding Mrk 820 in this image is a good sampling of other galaxy types, covering almost every type found on the Hubble Tuning Fork, both elliptical and spiral. Most of the smears and specks are distant galaxies, but the prominent bright object at the bottom is a foreground star called TYC 4386-787-1.
The first shooting stars of 2015 belong to the the Quadrantids, a shower that peaks on the night of 3rd/4th January. Despite the interference of a gibbous Moon, expect some bright, sometimes blue and yellow coloured meteors that may leave glowing trails.
Hot on the heels of terrestrial fireworks ushering in the New Year, it’s time for some celestial pyrotechnics from the Quadrantid meteor shower – the year’s first major display of shooting stars – on 4 January. With an old waning crescent Moon not rising until nautical dawn in the UK, dark skies could see up to 80 meteors per hour around 2am GMT.
Countless galaxies vie for attention in this monster image of the Fornax Galaxy Cluster, some appearing only as pinpricks of light while others dominate the foreground.
