Not all galaxies appear to us on Earth as face-on spiral structures: some are angled edge-on from our perspective, like the Needle Galaxy, for example, or galaxy NGC 3628 in the Leo Triplet.
Edge-on galaxy NGC 891 is 30 million lightyears away in the Andromeda constellation, and spans about 100,000 lightyears across.
NGC 891 is also known as Caldwell 23: part of the deep-sky Caldwell Catalogue compiled by Sir Patrick Moore, who famously said the galaxy looks like "two fried eggs clapped back to back".
A Hubble Space Telescope image showing a section of edge-on galaxy NGC 891. Credit: ESA/Hubble & NASA. Acknowledgement: Nick Rose
Observations of NGC 891 with the Hubble Space Telescope have revealed that the galaxy’s galactic halo - a sphere of thinly-dispersed stars and other cosmic material surrounding the galaxy - mostly contains ancient stars, many of which are found grouped in some of the most ancient objects in the Universe: globular clusters.
Hubble data also suggests that the halo is comprised of material similar in composition to other material in NGC 891, which could mean it has been expelled from the main galaxy and is expanding outwards into space.
The expulsion of this cosmic material may be caused by intense star birth or the explosion of ageing stars in events known as supernovae.
Edge on Galaxy NGC 891 by Bill Snyder, Connellsville Pa. USA. Equipment: Planewave 17in, Apogee U16, Paramount ME, Astrodon LRGB. Exposures R 1.5Hrs G 1.5Hrs B 1.5Hrs L 5.8Hrs LRGB 10min subs.
NGC 891 is a spiral galaxy, and while we may never get to appreciate its spiral structure face-on, its edge-on tilt relative to Earth gives astronomers an amazing view of the dark lane of cosmic dust and gas running through the galactic centre.
Below is a selection of pictures of edge-on galaxy NGC 891 captured by astrophotographers and BBC Sky at Night Magazine readers from around the world.
Edge on Galaxy NGC 891 by Simon Hollingdale, Sussex, UK. Equipment: C925 with 0.6 focal reducer, Atik 314L mono CCD with RGB filters, Skywatcher NEQ6 mount guided using web cam and finder scope.Edge on Galaxy NGC 891 by Chris Price, Cedartown GA. USA. Equipment: SkyWatcher 100ed APO, Celestron Advanced GT mount, Canon T3i.Edge on Galaxy NGC 891 by Chris Price, Cedartown GA. USA. Equipment: SkyWatcher 100ed APO, Celestron Advanced GT mount, Canon T3i.Edge on Galaxy NGC 891 by Mark Griffith, Swindon, Wiltshire, UK. Equipment: Teleskop service 12" Richey-Chretien telescope, Skywatcher EQ8 mount,Atik 383L camera, Astronomik LRGB filters, Hutech IDAS light pollution filter.Edge on Galaxy NGC 891 by Ron Brecher, Canada. Equipment: SBIG STL-11000M camera, Baader LRGB filters, 10" f/6.8 ASA astrograph, Paramount MX. Guided with STL-11000's internal guider.Edge on Galaxy NGC 891 by Terry Hancock, Michigan, USA. Equipment: 12" RC, QHY16200 Monochrome CCD,LRGB Filters.Edge on Galaxy NGC 891 by Dan Crowson, Animas, New Mexico, USA. Equipment: SBIG STF-8300M, Astro-Tech AT12RCT.Edge on Galaxy NGC 891 by Philip, Bamford, Derbyshire, UK. Equipment: Skywatcher 300PDS, Canon 60Da camera, NEQ6 Mount.Edge on Galaxy NGC 891 by Phill Froggett, Buckland, Hertfordshire, UK. Equipment: QHY8L cooled to -15, Skywatcher200p and NEQ6 (belt modified), Guided with an ASI120MC-s and PHD2.Edge on Galaxy NGC 891 by Mark Griffith, Swindon, Wiltshire, UK. Equipment: Celestron C11 Sct, Skywatcher NEQ6 pro mount,Atik 383L camera, motorised filter wheel and Astronomik filters.Edge on Galaxy NGC 891 by Brian. M. Johnson, Kelling Heath, UK. Equipment: Televue NP127
