The Pinwheel Galaxy, home of a famous supernova and bright blue arms filled with newborn stars

The Pinwheel Galaxy M101 is a spiral galaxy 170,000 lightyears across, located 25 million lightyears away from Earth in the Ursa Major constellation.

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Published: March 21, 2024 at 2:40 pm

The Pinwheel Galaxy, also known as M101, is a spiral galaxy that measures 170,000 lightyears across and is located 25 million lightyears away from Earth in the Ursa Major constellation.

The galaxy is about twice the diameter of our own galaxy the Milky Way and is thought to contain about 1 trillion stars.

Hubble’s image of the Pinwheel Galaxy, M101, was captured over 10 years. Credit: NASA, ESA, K. Kuntz (JHU), F. Bresolin (University of Hawaii), J. Trauger (Jet Propulsion Lab), J. Mould (NOAO), Y.-H. Chu (University of Illinois, Urbana) and STScI.
Hubble’s image of the Pinwheel Galaxy, M101, was captured over 10 years. Credit: NASA, ESA, K. Kuntz (JHU), F. Bresolin (University of Hawaii), J. Trauger (Jet Propulsion Lab), J. Mould (NOAO), Y.-H. Chu (University of Illinois, Urbana) and STScI.

Images of the Pinwheel Galaxy show a predominance of scorching hot young stars glowing bright blue within the arms of the spiral galaxy.

These regions are subject to intense bursts of star formation among the cosmic dust and gas, within molecular hydrogen clouds.

The Pinwheel Galaxy was discovered by Perre Méchain, a colleague of Charles Messier, in 1781, and Messier eventually included it in his famous Messier Catalogue of deep-sky objects.

How to see the Pinwheel Galaxy

Chart showing the Plough asterism in Ursa Major and the location of the Pinwheel Galaxy, M101, above star Alkaid. Credit: BBC Sky at Night Magazine
Chart showing the Plough asterism in Ursa Major and the location of the Pinwheel Galaxy, M101, above star Alkaid. Credit: BBC Sky at Night Magazine

If you would like to observe the Pinwheel Galaxy or photograph it, it is best seen in the northern hemisphere in April and can be observed through a small telescope.

You can find it quite easily by locating the Plough or Big Dipper asterism in the constellation Ursa Major.

Imagine the Plough as a saucepan, and locate star Alkaid at the very end of the saucepan's handle. Above it you'll find the Pinwheel Galaxy.

Pinwheel Galaxy supernova

Supernova   M101 in 'before and after' images captured by Paul Jacklin, 16 May and 20 may.
Supernova M101 in 'before and after' images captured by Paul Jacklin, 16 May and 20 may.

The Pinwheel Galaxy has become famous more recently due to the discovery of a supernova within one of its spiral arms.

The closest supernova to Earth in five years, designated SN 2023ixf, was discovered in one of its spiral arms on 19 May 2023 by amateur astronomer Koichi Itagaki.

It was subsequently observed and imaged by many an enthusiastic observer and astrophotographer, generating quite a buzz online and on social media.

The Pinwheel Galaxy, Rouzbeh Bidishahri, Vancouver, Canada, 10 June 2021. Equipment: QHY268M camera, Planewave CDK12.5 astrograph, Astro-Physics 1100 GTO mount
The Pinwheel Galaxy, Rouzbeh Bidishahri, Vancouver, Canada, 10 June 2021. Equipment: QHY268M camera, Planewave CDK12.5 astrograph, Astro-Physics 1100 GTO mount

Images

Below is a selection of some of the best pictures of the Pinwheel Galaxy captured by BBC Sky at Night Magazine readers and astrophotographers around the world.

For more astrophotography, read our astrophotography guides or discover our pick of the best astrophotography cameras.

And don't forget to send us your images or share them with us via Facebook, Twitter and Instagram.

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