Who Was Charles Messier?

Charles Messier was a French astronomer who lived from 1730 to 1817. Working in Paris during the late 1700s, Messier was passionate about discovering comets. In an era when comet discoveries brought great scientific prestige, he spent countless nights scanning the skies with a 100 mm refracting telescope.

While searching for comets, Messier repeatedly encountered faint, fuzzy objects that looked similar to comets but did not move across the sky. To avoid confusing these objects with real comet discoveries, he began recording their positions.

That list eventually became one of the most famous catalogs in astronomy.

What is the Messier Catalogue?

The Messier Catalogue is a list of 110 deep-sky objects including galaxies, nebulae, and star clusters. Messier created the catalog to help astronomers quickly identify objects that were not comets, but the list eventually became something much more valuable.

Today, the Messier objects are some of the most famous observing targets in the night sky. All are bright enough for small telescopes and binoculars under dark skies, making them ideal objects for amateur astronomers.

Some of the most famous Messier objects include:

• M13 – The Great Hercules Cluster: A dense globular cluster containing hundreds of thousands of stars.

  

• M31 – The Andromeda Galaxy: The closest major galaxy to the Milky Way and visible to the naked eye under dark skies.

  

• M33 – The Triangulum Galaxy: A large spiral galaxy in our Local Group.

  

• M42 – The Orion Nebula: A stellar nursery where new stars are actively forming.

  

• M45 – The Pleiades: A bright open cluster often called the Seven Sisters.

  

• M81 & M82 – Bode’s Galaxy and the Cigar Galaxy: A striking galaxy pair in Ursa Major.

  

• M101 – The Pinwheel Galaxy: A large face-on spiral galaxy with beautiful arms.

  

What is a Messier Marathon?

A Messier Marathon is an observing challenge where astronomers attempt to view all 110 Messier objects in a single night.

This is only possible during a short window in March, when the position of the Earth allows all the objects to be visible between dusk and dawn. Earlier in the winter some objects are too close to the Sun, while later in spring others set before darkness begins.

Because the challenge requires the entire night, dark skies and careful planning are essential.

When, Where, and How Should I Marathon?

The best time to attempt a Messier Marathon is during the new moon, when the sky is at its darkest. In 2026, the new moon occurs on March 18, making the surrounding nights excellent opportunities for the challenge.

A particularly good time for Denver-area observers will be the Denver Astronomical Society Dark Sky Weekend at the Kline-Dodge Dark Site from March 13–15. Located east of Deer Trail, the Kline-Dodge site offers dark skies and wide horizons that are ideal for marathon observing.

If you’re looking for other observing locations around the metro area, check out our guide: Where to Explore the 2026 Denver Night Skies. This article highlights dark-sky locations across the Front Range and throughout Colorado.

Tips for a Successful Marathon

Completing a Messier Marathon takes preparation and endurance. Here are a few tips to improve your chances of success:

Pick the Right Location and Night
Choose a site with dark skies and clear horizons. The fewer obstructions you have near the horizon, the easier it will be to catch objects that are rising or setting.

Prepare Before Sunset
Set up your telescope while it’s still light outside and make sure your finder scope, charts, and equipment are ready.

Follow a Strategic Sequence
Some objects are only visible for a short time near dusk or dawn, so the order you observe them matters.

Stay Flexible
If you can’t locate an object quickly, move on and come back later rather than losing valuable time.

Take Care of Yourself
Bring warm clothing, snacks, and hot drinks. A Messier Marathon can last up to 12 hours, so staying comfortable makes a big difference.

Recommended Messier Marathon Sequence

(for ~40° N latitude such as Denver and the Kline-Dodge Dark Site)

Below is the recommended observing sequence of the Denver Astronomical Society grouped by hour blocks. The Optical Aid column shows whether the object is commonly observable with the naked eye, binoculars, or telescope under dark skies. You can also download this list in either a csv (Excel) or skylist (SkySafari) format. If you’d like to create your own sequence, a great resource can be found at Larry McNish’s Messier Marathon Planner.

Targets marked with ☀️ will be difficult to see due to the sunlight and the target’s close position to the horizon.

Keep Looking Up

The Messier Marathon is one of the most exciting challenges in amateur astronomy. Whether you attempt all 110 objects or simply spend the night exploring a few of your favorites, the experience connects you with centuries of astronomical discovery.

If you plan to take on the challenge this March, consider joining fellow observers at the Kline-Dodge Dark Site during the March 13–15 Dark Sky Weekend, when the moonless skies will offer ideal conditions.

With good planning, warm clothing, and plenty of coffee, you might just complete the entire Messier Catalogue in one unforgettable night.

Clear skies and happy marathoning!