Messier 101

Date: 26 April 2022

Altitude: 59 - 64 degrees

Angular Size: 1° 00' x 0° 45'

Position Angle: 1° 01' from north through east

Orientation: North up; East left

Pixel scale: 1.30" per pixel

Total exposure time: 62 minutes

B filter: 33 x 45 seconds

V filter: 33 x 37 seconds

R filter: 33 x 30 seconds

Messier 101 is also known as NGC 5457 and the “Pinwheel Galaxy”

Galaxy: classification SABc

Constellation: Ursa Major

Diameter: 200,000 light years

Distance: 21 million light years

Age: 330 million years


The galaxy is asymetrical due to interactions with other galaxies. It has a high population of H

II regions, many of which are very large and bright due to ionizaton by large numbers of ex-

tremely bright and hot young stars. Some of these are prominent enough to receive New

General Catalogue numbers.

The galaxy was discovered by Pierre Méchain in 1781, and verified by Charles Messier, who

included it as one of the final entries in the Messier Catalogue.