But before Messier cataloged it, another famous astronomer — Edmond Halley — discovered it. M13 is a globular cluster, so called because of its round shape.
Under a dark sky, you’ll spot M13 easily as a fuzzy “star” two-thirds of the way from Zeta (ζ) to Eta (η) Herculis, two of the stars in the constellation’s famous “Keystone” asterism. The Hercules Cluster contains many relatively bright stars, so you’ll be able to fully resolve them through even a 3-inch telescope.
Of the sky’s 10 brightest globular clusters, only two lie in the northern sky. M13, however, sits 35° higher than the other, M5, so it’s the brightest globular most amateur astronomers are familiar with.
Summer star parties just wouldn’t be the same without the Ring Nebula. At a glance, this object — a gaseous ring surrounding a faint white-dwarf star — illustrates the fate of Sun-like stars. In addition, the Ring is easy to find, midway between the Beta (β) and Gamma (γ) stars of the bright constellation Lyra.
Through a small telescope, the Ring Nebula appears ever-so-slightly oval-shaped, stretched in an east-west direction. At low magnification, it might appear evenly illuminated. Crank up the power, and you’ll see the outer ring’s brightness begin to outpace that of the central region.
Summer north of the equator is — by far — the best time to view our galaxy’s rich star fields. Numerous surprises await you. One is the spectacular Wild Duck Cluster that seems to fly through the Milky Way.
The common name originated in a book written by Admiral William Smyth in 1844. Of M11, Smyth wrote, “A splendid cluster of stars in the upper-right corner of Scutum the Shield. This object, which somewhat resembles a flight of wild ducks in shape, is a gathering of minute stars.”
From a dark site, those of you with sharp eyes will spot M11 with your unaided eyes. Just follow a curved line of stars of decreasing brightness. Start with 3rd-magnitude Lambda (λ) Aquilae; move to 4th-magnitude 12 Aquilae; finally, proceed to 5th-magnitude Eta (η) Scuti, which will lead you to M11.
Any size telescope will reveal several dozen stars in this cluster. Bigger scopes and higher powers will help you resolve additional stars, but some observers think a low-power view is best. Start by scanning M11’s core, which resembles a poor globular cluster. From it, streamers of stars and dark lanes emanate in all directions.
Good luck making the shape of a fox out of the stars of the constellation Vulpecula. This faint star pattern’s brightest star is magnitude 4.4 Alpha (α). But you won’t be pointing your telescope at Vulpecula to look at stars. You’ll be looking for the Dumbbell Nebula, also known as M27.
Messier discovered the Dumbbell Nebula July 12, 1764, making it the first planetary nebula discovered. He made it number 27 on his famous list.
The Dumbbell Nebula owes its common name to a double-lobe shape common among planetary nebulae. Astronomers think double stars may explain this shape. Strong magnetic fields also could have produced M27.
Even through binoculars, this object is easy to spot. To see its details, however, you’ll need a telescope.
Small telescopes show the two bright lobes and several stars scattered across M27’s face. This object responds well to high magnifications because of its high surface-brightness.
Few deep-sky objects with “common” names truly look like their namesakes. Not so with the North America Nebula, which also carries the designation NGC 7000. A quick glance at this object reveals the California coast, Mexico, the Gulf of Mexico, and even a faint Florida. It took more than 100 years, however, for people to see the similarity.
Sir William Herschel discovered the North America Nebula in 1786. German astronomer Max Wolf was the first to photograph it, in 1890. He dubbed it the America Nebula, and that’s where it gets its current name.
From a dark site, sharp-eyed observers can see NGC 7000 with their naked eyes. Look roughly 3° east of Deneb (Alpha [α] Cygni). You won’t see the whole continent at first glance. Find the brightest part — Mexico — then patiently, and with averted vision, try to see the rest.
Binoculars give a better view, as do small telescopes. Low-power eyepieces that provide at least a 2° field of view are best.
Our next summertime treat is the beautiful double star Albireo, also known as Beta (β) Cygni. This star marks the head of Cygnus the Swan, and, to the naked eye, it looks quite ordinary.
Point a small telescope at it, however, and you’ll split Albireo into a pair of colored stellar gems. To most observers, the brighter star appears golden, and its companion is a sapphire-blue.
I say “to most observers” because the eye’s color receptors vary a bit from one person to the next. So, you might see “white and blue” or “orange and green.” That’s OK. Star colors are not absolutes.
Although you can split Albireo with a low-power eyepiece, crank up the magnification to 100x or more so there’s some space between the two stars.
The constellation Scorpius offers several deep-sky treats visible with the unaided eye. Two of its standout deep-sky objects — open clusters M6 and M7 — lie about 5° east-northeast of the two bright stars that mark the Scorpion’s stinger. M7 is the brighter of the two, and it’s sometimes called Ptolemy’s Cluster. You’ll spot it easily from any reasonably dark site.
Greek philosopher Ptolemy mentioned M7 around A.D. 130, describing it as a “nebula following the sting of Scorpius.” Messier added it to his catalog in 1764. M7 is the southernmost object in his catalog.
M7 is large enough that 4 Full Moons could fit within its borders. Because it is so big, you’ll need to use a low-magnification eyepiece to observe the entire cluster. When you do, notice how the background richness of the Milky Way enhances the view.
Or, you can try this: Crank up the power and look for double stars, patterns the cluster’s stars form, or gaps between lines of stars that many observers have described. Through 10×50 binoculars, you’ll count 50 stars in M7. Double the aperture to a 4-inch telescope, and you’ll double the number of stars you see.
Around 1680, English astronomer John Flamsteed (1646-1719) discovered what became the eighth object on Messier’s list — the magnificent Lagoon Nebula, also known as M8.
You’ll easily spot this object with your naked eyes from a dark site. It measures 3 times as wide as the Full Moon, and you’ll be able to follow most of the nebulosity through your telescope.
A dark lane (the lagoon) cuts the object in half. On the eastern side of the rift, you’ll see three dozen stars of open cluster NGC 6530 embedded in the gas.
The brightest star west of the lane is 8th-magnitude 9 Sagitarii, which is responsible for the nebula’s glow. A bit more to the west is M8’s core, a region of intense brightness. Look for the Hourglass Nebula, a star-forming region with lots of young stars.
Only 1.5° north-northwest of M8 is the Trifid Nebula, an object Messier discovered in 1764. This object owes its common name to three dust lanes that converge in front of the emission nebulosity.
From a dark site, a small telescope will show you a lot of detail in this object. Look for a nice triple-star system just west of center.
These three stars, and two more, provide the ultraviolet radiation that causes M20 to glow. On the Trifid’s northern edge sits a reflection nebula, shown as blue in photos. This region reflects the light of the 9th-magnitude star that sits at its center.
Our final object is globular cluster M22. This easy naked-eye object ranks as the sky’s third-brightest globular.
When you observe M22, altitude (how high it appears in the sky) is everything. Many amateur astronomers in northern Europe, Canada, and the northern United States don’t know how great this cluster is because, for them, it hugs the southern horizon. See it high in the sky, however, and you’ll understand why it made this list.
Through even a 4-inch telescope, you’ll see a brilliant, condensed core with dozens of stars around it. Along with the cluster, pay attention to the bright starry background. I think it adds character to the scene. Try to figure out exactly where the outer boundary of M22 ends and the background begins.