Complete guide to the glorious spiral galaxy known as the Whirlpool
The iconic Whirlpool Galaxy is a favourite deep-sky target for astronomers and astrophotographers alike.
By Lee Dyson
Published: Friday, 16 February 2024 at 12:06 PM
Could the Whirlpool Galaxy, M51, be the most famous galaxy in astronomy? It’s certainly among the most recognisable, and probably one of the first galaxies that can be confidently identified by newcomers to deep-sky astronomy and astrophotography.
The Whirlpool Galaxy is 31 million lightyears from Earth in the constellation Canes Venatici and is observable through a small telescope.
Hubble Space Telescope’s infrared view of galaxy M51, the Whirlpool Galaxy. Credit: NASA, ESA, M. Regan and B. Whitmore (STScI) and R. Chandar (University of Toledo, USA)
What the Whirlpool Galaxy looks like
The Whirlpool Galaxy has a beautiful face-on appearance, as seen from Earth, enabling observers to make out its distinct spiral structure and luminous galactic core.
The spiral arms are packed with stars, gas and dust and make for the perfect conditions for new stars to be born, as that gas and dust coalesces, compresses and collapses to ignite star-birth.
In images of the Whirlpool Galaxy, hot young stars can be seen glowing bright blue along the arms, while older, yellower stars are seen glowing closer to the centre.
Whirlpool Galaxy by Steve Porter, Bardsey Island, North Wales, UK. Equipment: Meade 10″ LX 200 ACF, EOS 6.
The Whirlpool Galaxy is probably so easily recognisable due to dwarf galaxy NGC 5195, which is the yellowish splurge seen at the end of one of the Whirlpool Galaxy’s spiral arms.
NGC 5195 is gravitationally interacting with the Whirpool Galaxy, pulling on the spiral arm and precipitating new bouts of star formation in the process.
Observations using the Hubble Space Telescope have actually suggested that NGC 5195 is passing behind the Whirlpool.
Messier 51, also known as the Whirlpool Galaxy, as seen by the Hubble Space Telescope. Credit: NASA, ESA, S. Beckwith (STScI) and the Hubble Heritage Team (STScI/AURA)
Whirlpool Galaxy and the Messier Catalogue
The Whirlpool Galaxy is also known as M51, making it the 51st entry on Charles Messier‘s famous list of astronomical deep-sky objects, the Messier Catalogue.
M51 was discovered by Messier in 1773 and added to his list. Messier was a prolific comet hunter, and created a catalogue of objects that might be mistaken for comets in the night sky in order to increase his chances of spotting the real deal.
The Messier Catalogue has since become a sort of ‘who’s who’ of famous deep-sky objects that astronomers love to observe through their telescopes.
How to find the Whirlpool Galaxy
Chart showing the location of M51, the Whirlpool Galaxy, in Canes Venatici. Click on the chart to expand. Credit: BBC Sky at Night Magazine
The Whirlpool Galaxy can be found in the night sky by locating star Alkaid in the Plough asterism, which is part of the constellation Ursa Major.
Head in the direction of Canes Venatici and you’ll be able to spot the Whirlpool Galaxy through your telescope.
Use our chart above to help you locate it.
The Whirlpool Galaxy can be seen high in the sky during spring in the Northern Hemisphere.
A GALEX ultraviolet image of the Whirlpool Galaxy. Credit: NASA/JPL-Caltech
Below is a selection of images of the Whirlpool Galaxy captured by BBC Sky at Night Magazine readers and astrophotographers from around the world.
Illustration showing the distribution of diazenylium molecule radiation in the Whirlpool Galaxy. Credit: Thomas Müller (HdA/MPIA), S. Stuber et al. (MPIA), NASA, ESA, S. Beckwith (STScI) und das Hubble Heritage Team (STScI/AURA)Credit: Thomas Müller (HdA/MPIA), S. Stuber et al. (MPIA), NASA, ESA, S. Beckwith (STScI) und das Hubble Heritage Team (STScI/AURA)
M51, the Whirlpool GalaxyAlex Battù and Luca Barcaro, captured remotely via Pixel Skies, Castillejar, Spain, 3 February-25 March 2023Equipment: ZWO ASI6200MM Pro mono CMOS camera, Tecnosky Astrografo Fast 300 astrograph, iOptron CEM120 mount
A chart showing how to find the Whirlpool Galaxy
Hubble Space Telescope’s infrared view of galaxy M51, the Whirlpool Galaxy. Credit: NASA, ESA, M. Regan and B. Whitmore (STScI) and R. Chandar (University of Toledo, USA)
Magnetic field lines of the Whirlpool Galaxy mapped by SOFIA, shown over a Hubble Space Telescope image of the galaxy. Credit: NASA, the SOFIA science team, A. Borlaff; NASA, ESA, S. Beckwith (STScI) and the Hubble Heritage Team (STScI/AURA)
The Whirlpool Galaxy, Kasra Karimi, Aylesbury, 18–19 April 2021. Equipment: ZWO ASI 6200MC camera, TS-Optics 130mm apo triplet, Sky-Watcher EQ6-R Pro mount. Exposure: 75x 300”
M 51 Whirlpool Galaxy by Matt Herbik, Canadensis PA,USA. Equipment: 8″ RC telescope at f8, Software Bisque MyT mount, QSI 683, Astrodon filters
M51 – The Whirlpool Galaxy by Duan Yuseff, Canvey Island, Essex, UK. Equipment: Ikharos 10″ Truss RC telescope, SW EQ8 Mount, ZWO ASI1600MM-C, ZWO Filter Wheel, Badder 36mm NB Filters, Lodestar Guide Cam, Primaluce Lad Airy 72 Guide scope
Whirlpool Galaxy by Steve Porter, Bardsey Island, North Wales, UK. Equipment: Meade 10″ LX 200 ACF, EOS 6.
M51 – Whirlpool Galaxy by David Attie, Abu Dhabi, UAE. Equipment: C11, focal reducer x0.63, Az-Eq6, OAG Skytrack, Lodestar x2, Moravian G2-4000 internal filter wheel (Baader filters)
M51 Whirlpool Galaxy by Roger Brooker, Kent, UK. Equipment: GSO 8″ F4 Newt, Eq6Pro via eqmod, SXvH9, Baader LRGB filters. Guided with the Ts9mm OAG. Captured in Maxim DL, Processed in Pixinsight.
M51 Whirlpool Galaxy by Mark Griffith, Swindon, Wiltshire, UK. Equipment: Celestron C11 Sct, Skywatcher NEQ6 pro mount,Atik 383L camera, motorised filter wheel and Astronomik filters.
M51 – Whirlpool Galaxy by Bill McSorley, Leeds, UK. Equipment: SW 150P Newtonian, EQ5 GoTo Mount, QHY8L cooled ccd camera.
M51 Whirlpool Galaxy by Jason Wiseman, Paignton, Devon, UK. Equipment: Celestron C9.25, Nikon D90
M51 by Chris Grimmer, Norwich, UK. Equipment: 10″ Astrosib RC, Starlight Xpress SXVR H694, Ioptron CEM60
Many of the 3rd Earl’s sketches and notes are available to view in the Science Centre at Birr Castle. This one shows sketches made during observations of the Whirlpool GalaxyCredit: Iain Todd/BBC Sky at Night Magazine
The Whirlpool Galaxy Daniel Mills, Hill Head, Hampshire, 15 May 2020. Equipment: Canon 600D DSLR, Sky-Watcher Explorer 130P-DS reflector, Sky-Watcher HEQ5 Pro mount
Messier 51, also known as the Whirlpool Galaxy, is one of the most famous examples of a beautiful spiral galaxy.Credit: NASA, ESA, S. Beckwith (STScI) and the Hubble Heritage Team (STScI/AURA)
Whirlpool Galaxy, David Attie, Abu Dhabi, UAE, 9 April 2016. Equipment: Moravian G2-4000 CCD camera, Celestron C11-A XLT Schmidt-Cassegrain, Sky-Watcher AZ-EQ6 GT mount.
A view of the Whirlpool Galaxy in optical light (white) and radio waves (red). Credit: NRAO/AUI/NSF; HST composite by B. Saxton
A GALEX ultraviolet image of the Whirlpool Galaxy. Credit: NASA/JPL-Caltech
The Whirlpool GalaxyHaim Huli, Namibia, June 2022Equipment: Moravian C3 Pro camera, ASA RC600 24-inch F4.5, ASA DDM200 mount
The Whirlpool Galaxy by John Cave, Huyton, Merseyside, UK. Equipment: 2m John Moore’s Telescope at La Palma.
