Key Takeaways:
- The New Moon occurs on December 18 at 8:43 P.M. EST, providing optimal conditions for viewing deep-sky objects.
- The Triangulum Galaxy (M33), a 6th-magnitude spiral galaxy in western Triangulum, is recommended for observation, positioned approximately 7° southeast of Mirach in Andromeda.
- Despite its magnitude, M33 exhibits low surface brightness, suggesting the use of binoculars or wide-field telescopes for initial detection before employing higher magnifications to resolve its brighter core and fainter spiral arms.
- M33 is a member of the Local Group of galaxies, located 2.7 million light-years away and spanning 70’ by 45’, with larger scopes potentially resolving the NGC 604 star-forming region within it.
Looking for a sky event this week? Check out our full Sky This Week column.
December 18: Mercury on the move
New Moon occurs at 8:43 P.M. EST. This is the best time to view deep-sky objects, so let’s set our sights on the lovely spiral galaxy M33, also known as the Triangulum Galaxy.
Highest in the sky around 8 P.M. local time, you’ll find M33 80° high in the south at this time. The 6th-magnitude galaxy is located in western Triangulum; the nearest bright star is 2nd-magnitude Mirach in Andromeda. From this star, the galaxy lies just 7° to the southeast.
Although M33 shines at 6th magnitude, its surface brightness is relatively low. The best way to find it is to search with binoculars or a wide-field scope, locating it first before zooming in with higher magnifications to look for structure, such as its brighter core and fainter spiral arms. Located some 2.7 million light-years away, M33 spans about 70’ by 45’ on the sky. It is a member of our Local Group of galaxies, along with the Andromeda Galaxy and numerous smaller members.
Observers with larger scopes can look for NGC 604, a bright star-forming region within M33, located northeast of its nucleus.
Sunrise: 7:18 A.M.
Sunset: 4:37 P.M.
Moonrise: 7:19 A.M.
Moonset: 4:01 P.M.
Moon Phase: New
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 10 P.M. local time from the same location.
