Pinwheel Galaxy
What is Pinwheel Galaxy?
Galaxies· Distance ~21 million ly. A huge face-on spiral, 1.7 times the Milky Way's size, with more than 3,000 red star-forming regions studding its wide-flung arms. Its slightly lopsided shape records interactions with satellite galaxies; a supernova here in 2023 drew worldwide attention.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Pinwheel Galaxy is in your sky right now: https://nowsky.org/solar/sky?sel=pinwheel galaxy — location and time set automatically, no login.
Its place in the sky
A galaxy, in the direction of Canes Venatici, spanning about 29 arcminutes of sky — 0.9 times the width of the full Moon.
Distance and scale
| Distance | ~21 million ly |
|---|---|
| Diameter | ~170,000 ly |
| Stars | ~1 trillion |
| Constellation | Ursa Major |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Discovery and name
A face-on spiral twice the Milky Way's size; supernova SN 2023ixf erupted here in 2023.
Frequently asked
- How far is Pinwheel Galaxy from Earth?
- ~21 million ly.
- How big is Pinwheel Galaxy?
- ~170,000 ly.
- Where in the sky is Pinwheel Galaxy?
- In the direction of Canes Venatici.
- Where is Pinwheel Galaxy in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
SN 2023ixf, the most-observed supernova
On 19 May 2023 the Japanese amateur Koichi Itagaki discovered a supernova in M101. Brightening to 11th magnitude at 21 million light-years, it drew telescopes worldwide within hours of discovery and remains the most densely observed supernova to date. In the first days the light of the debris breaking through dense gas around the star was caught, confirming that the star had shed a great deal of material in the years before it exploded.
The star at the site had been photographed by Hubble and Spitzer: a red supergiant of 10 to 20 solar masses whose brightness had fluctuated in the years before the explosion — a rare case of matching pre- and post-explosion data to see what a star does just before it dies. Because M101's disk faces us, the supernova was not hidden by dust, and Itagaki added the find to a personal tally of more than 170 supernova discoveries.
The galaxy in depth
The Pinwheel Galaxy, M101, is a spiral about 21 million light-years away in Ursa Major. Its disc faces us directly, so the arms spread out like a pinwheel; at some 170,000 light-years across it is 1.7 times the Milky Way's size and holds around a trillion stars. Spread so wide, though, its surface brightness is low, and it shows only faintly outside dark skies.
Méchain discovered it in 1781, near the end of the Messier catalogue. Hubble's 2006 mosaic of M101 was the largest, most detailed galaxy image the telescope had made, revealing more than 3,000 giant emission nebulae strung along the arms. The galaxy's lopsided outline is the work of several satellite galaxies tugging at it. In May 2023 Supernova 2023ixf exploded here, bright enough for amateur telescopes and observed by enthusiasts worldwide.
It forms a triangle above Mizar and Alkaid at the end of the Big Dipper's handle. Select the Pinwheel in the Sky view to mark it; to see it for real, pick a moonless night and a low-power, wide field, and a hazy patch will emerge.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.