Messier 108, also known as NGC 3556, is a galaxy located in the constellation Ursa Major and can be observed on spring nights in the northern hemisphere. Discovered by the French astronomer Pierre Méchain on February 18, 1781, this surfboard-looking galactic structure is around 45 million light-years away from Earth!
M 108 appears elongated because we see it edge-on. See my photo and drawing below. It has a bright central region and is best viewed by suburban astronomers under clear, moonless skies. When observed through small or moderate-sized telescopes, the galaxy will appear as a wispy thin line or haze. This is why astronomers often refer to M 108 as the Surfboard Galaxy.
I recommend the following video on YouTube for additional insight on M 108:
My Observations
| Date | March 15, 2024 |
| Time | 10:15 p.m. |
| Location | Seattle, WA |
| Magnification | 169x |
| Scope | Meade 8″ SCT |
| Eyepiece | 12mm |
| Seeing | Average |
| Transparency | Average |
from the Seattle suburbs.
Photo shot on March 15, 2024, from Seattle, Washington.
45-min exposure.
Despite repeated attempts, I struggled to observe M108 through my 8-inch telescope. I then used averted vision as I scanned the area. With each slight movement of the scope, I finally noticed a thin fuzzy streak near a dim star.
Key Stats
| Constellation | Ursa Major |
| Best Viewing | Spring |
| Visual Magnitude | +9.96 |
| Absolute Magnitude | -20.00 |
| Distance from Earth | 32 million ly |
| Diameter | 37,000 ly |
| Apparent Size | 4.0 x 1.7 arcmin |
| My Viewing Grade | C |
| Designations | M108, Messier 108, NGC 3556, Surfboard Galaxy, UGB 6225 |
Historical Observations
Observation by Pierre Méchain
“A nebula near Beta in the Great Bear. Mr. Messier mentions, when indicating its position, two others, which I also have discovered and of which one is close to this one [this is M108], the other is situated close to Gamma in the Great Bear [M109], but I could not yet determine their positions.”1
For additional historical observations, please see this page.
Sources
The banner photo of Messier 108 is by the Sloan Digital Sky Survey. Source photo. The file is licensed under the Creative Commons Attribution 4.0 International license.
1 (2007, March 4). Messier 108. SEDS: THE MESSIER CATALOG. Retrieved March 16, 2024, from http://www.messier.seds.org/Mdes/dm108.html
Sketch and Seestar photo by Wayne McGraw
The Garden Astronomer 