In the 17th century, Galileo first turned a telescope upward toward the heavens. By doing so, he revealed a treasure trove of nebulae, galaxies, comets and other deep sky gems never before seen. Centuries later astronomers are still cataloging all that we see but charting the heavens owes its first list to a man named Charles Messier.
Messier Charts the Sky
As more people began peering through telescopes, patterns in the sky began standing out. Some deep sky objects appeared to move from night to night, named comets, while others remained stationary, generally called nebulae at the time. Comet hunting became a popular pasttime for 18th century observers, and between 1758 and 1782, French Astronomer Charles Messier (pronounced MESS-ee-ay) set out to create a definitive list of deep sky objects that were not comets.
This way, observers could see an object and consult the list to find out if it was a comet or not since many comet-hunters were essentially finding the same bright deep sky objects and tracking them to see if the objects were newly found comets.
The Messier List
What Messier ended up with after his years of cataloging was a list of 110 of the sky’s prettiest galaxies, nebulae and star clusters that is a staple must-see for new observers today. The list is also used for aptly-named Messier Marathons, in which focused observers can techincally see all 110 objects in one night. The annual event occurs across the mid-Northern latitudes during the early months of Spring, when the conditions are best for the all-night race.
Though all originally called nebulae by early astronomers, optical refinement over the years revealed the list to actually be composed of:
- 12 Nebulae
- 26 Open star clusters
- 29 Globular clusters
- 40 Galaxies
- 3 non-deep sky objects, or asterisms
“M” Objects
Most observers refer to each object on the list as “M” followed by the object’s designated number. The Andromeda Galaxy, for example, is also known as “M31.” Many other Messier objects have been dubbed with more descriptive names, including:
- M27: The Dumbbell Nebula
- M11: The Wild Duck Cluster
- M64: The Blackeye Galaxy
The Messier Award
The list is so popular that the Astronomical League offers a certificate and pin for members who observe and log all 110 objects. The objects are bright enough that most small to midsize telescope owners will be able to find and see the objects with relative ease--anywhere from a 4.5 to 8 inches in aperature for reflectors and 1.5 to 3 inch reflectors. An observer who wants to see all the objects on the Messier list will probably need to purchase a star chart, however, even a beginner’s sky map will usually have the locations of these heavenly gems.
Messier Fever
What started as a simple catalog of objects to ignore has become one of the most celebrated observing lists for amateur astronomers.
Further Reading
Year-Round Messier Marathon Field Guide, by Harvard Pennington, Published 1997
Deep Sky Companions: The Messier Objects (Deep-Sky Companions), by Stephen James O'Meara, Published 2000
