Keenan's System
NGC 5216 and 5218 in Ursa Major
is a fascinating pair of interacting galaxies, 17,000,000 light-years from Earth. NGC 5216 (right) and NGC 5218 (left) have a debris trail between them, 22,000 light-years in length. P. C. Keenan noted this double galaxy in 1935 but his notes seem to have been overlooked, and the pair later ‘rediscovered’ by observers at the Lick and Palomar observatories. Both galaxies have a countertide- a fingerlike extension pointing in a different direction to the debris trail, a structure typical of interacting double galaxy systems. This photograph was acquired in 2008 from Linz, Austria by my friend Martin Winder. This image was selected as NASA's APOD (Astronomy Picture of the Day) for July 31, 2008.
is a fascinating pair of interacting galaxies, 17,000,000 light-years from Earth. NGC 5216 (right) and NGC 5218 (left) have a debris trail between them, 22,000 light-years in length. P. C. Keenan noted this double galaxy in 1935 but his notes seem to have been overlooked, and the pair later ‘rediscovered’ by observers at the Lick and Palomar observatories. Both galaxies have a countertide- a fingerlike extension pointing in a different direction to the debris trail, a structure typical of interacting double galaxy systems. This photograph was acquired in 2008 from Linz, Austria by my friend Martin Winder. This image was selected as NASA's APOD (Astronomy Picture of the Day) for July 31, 2008.