Messier Objects and Homebound Observing

Since we’re all spending a lot of time at home these days, now would be a cool time to do what’s called a “Messier Marathon”. It’s a one-night search for all the sky objects that astronomer Charles Messier cataloged while searching for comets. It’s something of a challenge, and not everybody finishes it, but the joy is in what you find while you’re on the hunt.

Messier’s Project

Charles Messier began studying the sky in the mid-18th century, and one of his goals was to record any comets that crossed the sky. Now, the sky is a big place, and there are a lot of things to observe. And, not surprisingly, as Messier searched for comets, he found a lot of other things that looked faint and fuzzy, but—alas—weren’t comets.

To update other observers, he decided to make a list of what he’d found and make it easier for comet hunters (especially) to ignore these objects. Today, the Messier Objects list contains information about 110 nebulae, star clusters, and galaxies and is referred to informally as “Messier Catalog”. It contains all the objects he personally studied by the naked eye and through his 100-mm telescope from his location in France, plus some others added later on.

What Are the Messier Objects?

The objects in Messier’s list range from star clusters to nebulae and galaxies. With today’s telescopes, it’s fairly easy to look at many of them and see some details. The star clusters he found, for example, make good targets and through a scope or a pair of binoculars, you can make out some individual stars in many of them. That’s better than Messier could see. Back in his day, these collections of stars probably looked fairly fuzzy through his telescope.

Other Messier objects, such as the globular cluster in the constellation Aquarius, are just barely visible to the naked eye. Brighter objects visible to the naked eye include the globular cluster M13 in Hercules.

There’s also M45, commonly known as the Pleiades. That one is a good example of an “open cluster,” a grouping of stars that travel through the galaxy together. They are usually “born” together in a batch. The stars remain loosely bound together by gravity for hundreds of millions of years. Eventually, they disperse as they travel through space. Compare an open cluster to a globular cluster. Those contain hundreds of thousands of stars and are globe-shaped stellar collections.

Messier Nebulae

Clouds of gas and dust in space are called “nebulae”. They exist throughout our galaxy and in many other galaxies as far astronomers can detect. Nebulae are much dimmer than stars. Some, such as the Orion Nebula (M42) or the Trifid Nebula (M20) in Sagittarius) are spottable with the naked eye. You just need good seeing conditions. The Orion Nebula is a starbirth region, while the Trifid is a cloud of hydrogen gas that glows. It’s called an “emission nebula” for that reason, and also has stars embedded in it.

The Messier list includes supernova remnants and planetary nebulae, which are “clouds” of a different sort. A Type II supernova, for example, occurs when a massive star dies. As part of the death process, it sends clouds of gas and other elements hurtling through space at high speed. One of the best-known Messier objects is called the Crab Nebula in the direction of the constellation Taurus, the Bull. It comprises the remains of a supermassive star that exploded thousands of years ago. The Crab is not visible to the naked eye. However, it can be viewed through a small telescope,

Not all stars die this way. Others, like our Sun, end up as planetary nebulae. In fact, our Sun WILL do that. Its outer layers will dissipate out to space. While that’s happening, what’s left of the Sun shrinks to become a white dwarf star.

Messier charted several of these faint little objects, including the famous Ring Nebula in the constellation of Lyra. It shows up at number57 on his list. It’s not visible to the naked eye but can be found using binoculars or a small telescope. If you do look at it through a fairly good telescope, you can spot a white dwarf at the heart of the ring.

Galaxies in the Messier List

There are 42 galaxies in the Messier Catalogue. The most famous is the Andromeda Galaxy, which is called M31. It’s the closest spiral galaxy to our own Milky Way. Most people can spot it with the naked eye on a good dark night (away from bright lights). It’s also the most distant object that can be seen with the naked eye. When you look at M31, you’re peering across about 2.5 million light-years of space. All other galaxies in the Messier Catalogue are visible only through binoculars (for the brighter ones). You need telescopes or binoculars for the dimmer ones.

“Running” a Messier Marathon

I mentioned above that it’s possible to see all the Messier objects in a one-night marathon. It is best to start in mid-March and can be done through mid-April. The prime viewing spots are from mid- to low-latitude areas in the northern hemisphere. If you want to do one, it’s best to start as soon after sundown as possible. Your search begins in the western part of the sky to catch a glimpse of any objects about to set.

Then, work your way east to try and see all 110 objects before the sky brightens near sunrise. Most observers who try this challenge spend much of the year looking for all the Messier objects individually. This familiarizes them with the area of the sky each object is in. This is particularly important for beginners.

You probably won’t get them all on your first try, but that’s okay. If you don’t have a telescope, try to get as many objects as you can with naked-eye or a pair of binoculars. What you discover along the way will bring you out night after night for more exploration. And, at a time when we’re all supposed to stay home, it’s a worthy goal for a skywatcher.

The Online Messier Hunt

Of course, not everybody wants to go outside and do observing. But, if you want to see all the Messier objects for yourself, there’s instant gratification online. The Hubble Space Telescope has observed most of the objects on the list. You can see many of the stunning images in the Space Telescope Science Institute’s Flickr catalog. Or, you can get a list of Messier objects (such as the one at Astropixels. Click on each object to get a full page of information about the famous sky sights that Messier made famous on his hunt for “famous fuzzy comets”.

The post Messier Objects and Homebound Observing appeared first on The Spacewriter’s Ramblings.