M100 (Galaxy)
A large face-on spiral in Coma Berenices, the brightest spiral of the Virgo galaxies on Messier's list (magnitude 9.5). Its distance comes from Cepheid variable stars in its arms: about 50 million light-years.
Galaxy in Coma Berenices. Magnitude 9.5.
Can you see it from Guyana?
From Georgetown (6.8° N) it climbs to 81° above the northern horizon at its highest; from Lethem (3.4° N), to 78° above the northern horizon. It is highest at midnight on the night of 26 Mar, in the middle of its season. The page works out tonight's rise, highest point and set for both towns in Guyana time (UTC-4), and where the Moon is.
What you'll see
- Your eyes: Not visible to the eye. It lies 8.3° east of Denebola.
- 10x50 binoculars: Just detectable in binoculars from a dark site, as a faint smudge.
- A small telescope (80 to 100 mm): A round glow with a bright core; its arms need a larger telescope and a dark sky.
- A camera: Tiny on camera: it needs 2,000 mm or more of focal length on a tracking mount. The photo above is a near-infrared VLT view.
How big, how bright, how far
- Size on the sky: 6.1′ × 5.6′, 20% of the Moon's width (the Moon is about 31′ wide).
- Brightness: magnitude 9.5. Fainter than the faintest stars in Georgetown (4.3) and Lethem (6.0): binoculars or a telescope.
- Distance: 50 million light-years. The light reaching your eye left it about 50 million years ago.
- True size: 93,000 light-years across its catalogued outline; light crosses it in 93,000 years.
Apparent size from OpenNGC (Mattia Verga), CC-BY-SA-4.0.
What it is made of
- Type
- Spiral galaxy, seen face-on
What is in it, not measured:
- Stars: an older central bulge and a disc of younger stars
- Gas and dust: in the spiral arms, where new stars form
- Dark matter: inferred from how fast it spins
How we know: Distance from Cepheid variable stars: NED-D (NASA/IPAC Extragalactic Database, redshift-independent distances), median of 27 Cepheids estimates: 16.10 Mpc, 14.52-17.28 Mpc (16th-84th percentile); e.g. 2008A&ARv..15..289T, 2006ApJS..165..108S, 2006A&A...452..423P; retrieved 2026-10-21. True size: the apparent size times the distance (apparent size: OpenNGC (Mattia Verga, CC BY-SA 4.0), commit 4e2398a2).
More deep-sky objects: Coma Pinwheel (M99) · M98 (Galaxy) · M85 (Galaxy) · M88 (Galaxy) · M84 (Galaxy) · M86 (Galaxy)