As the Earth makes its annual orbit around the Sun, we are able to see different constellations in the night sky depending upon the season of the year, and our location on the planet. While all observers have their own favorites when it comes to the constellations, the onset of summer in the northern hemisphere brings the return of a familiar crop of star constellations that each stargazer will no doubt welcome, albeit for different reasons.
In this article, however, I will take the opportunity to explore three of the summertime’s most prominent constellations namely Hercules, Cygnus, and Lyra. First of all, here is a brief overview of the constellations that you can see in the summer sky from the northern hemisphere.
Overview of the summer constellations
Famously heading the list of summer constellations are three contained within an asterism known as the Summer Triangle, which appears in the east during the early evening, before dominating the overhead sky around midnight. The three brightest stars in this arrangement are Deneb in Cygnus, Antlia in Aquila, and Vega in Lyra, with the Milky Way passing between the latter two stars in the triangle.
Not far north-east of the star Vega in Lyra is the constellation of Hercules, which is the night sky’s fifth largest constellation, and whose four main stars form an asterism called The Keystone, although it is sometimes difficult to spot because its stars are all between magnitudes of just 3 and 4.
Meanwhile, low in the southern sky can be found the stunning constellation of Scorpius, which resembles the scorpion that it depicts, and never rises much above the horizon as it makes its way across the summer sky. Scorpius lies on a band of sky reserved for zodiac constellations called the ecliptic, with one of its nearby companions including Sagittarius to its east, which is recognizable by its distinctive asterism known as The Teapot.
Finally, there are five circumpolar constellations that can be observed in the northern hemisphere throughout the year, regardless of the season, which are Ursa Major, Ursa Minor, Cassiopeia, Cepheus, and Draco.
Hercules Constellation
Although Hercules has no first-magnitude stars, it is one of the most iconic northern hemisphere summer constellations, with records of it dating back as it does to ancient Sumerian times. In fact, Hercules is so old that even the ancient Greek astronomers were somewhat uncertain as to its exact origins. Nonetheless, the constellation is associated with the Roman demigod Hercules, who has an equivalent in the Greek hero Heracles, who in his turn, appears to have been modeled on the Sumerian hero, Gilgamesh.
Hercules is one of the few constellations that do not require loads of imagination to recognize. The figure of a man-like creature is fairly easy to discern, especially when the Keystone asterism that marks out the figure’s “torso” is identified. Look for the star Alpha Herculis, (Ras Algethi) atop the Keystone; this star marks out the figures’ head in traditional depictions. One meteor shower, the Tau Herculids, is associated with the constellation.
Quick Hercules Facts
- Constellation: Hercules
Image Credit: Torsten Bronger - Coordinates: Between latitudes +90° and -50
- Best seen: 21:00 (9 p.m.) Local Time during the month of July
- Brightest star: Kornephoros (Beta Herculis)- Apparent magnitude: 2.81
- Stars with planets: 15
- Size: Fifth largest constellation
- Area: 1225 square degrees
- Neighboring constellations: Aquila, Boötes, Corona Borealis, Draco, Lyra, Ophiuchus, Sagitta, Serpens Caput, and Vulpecula.
Objects of Interest in Hercules
Despite its prominence in the summer sky, Hercules contains relatively few objects of real interest to amateur astronomers. However, it does contain two Messier objects, both of which are spectacular globular star clusters that are easy targets for small amateur telescopes.
Messier 92 (M92, NGC 6341) is located about 26,700 light years away with an estimated age of around 14.2 billion years, making it almost as old as the Universe and one of the oldest star clusters known.
The Hercules Globular Cluster (M13, NGC 6205,) is 22,200 light years away, 145 light-years wide, and contains about 300,000 stars that span a full 20 minutes of arc of the sky. The cluster was included in Messiers’ catalog in June of the year 1764. In 1974, a message, now known as the Arecibo Message, was transmitted toward M13 in the hope that hypothetical extraterrestrials living in the cluster might one day intercept it. However, by the time the message arrives at the cluster in 20,000 years’ time, the cluster will no longer be in its current position.
Cygnus Constellation
The brightest star in Cygnus is also the 19th most luminous star in the entire night sky. Like Hercules, this constellation actually look somewhat like the figure it represents, in this case a swan with outstretched wings. Cygnus contains the famous (and hard to miss) asterism called the Northern Cross, which is made up of the stars Deneb (Alpha Cygni), Delta Cygni, Albireo (Beta Cygni), Gienah (Epsilon Cygni) and Sadr (Gamma Cygni), marking the center of the asterism.
Quick Cygnus Facts
- Constellation:
Image Credit: “Cygnus constellation map negative” by This file: WikiPedant Original file: User:Bronger is licensed under CC BY-SA 4.0 - Coordinates: Between latitudes +90° and -40°
- Best seen: 21:00 (9 p.m.) Local Time during the month of September
- Brightest star: Deneb ( Alpha Cygni) – Apparent visual magnitude 1.25
- Stars with planets: 97
- Size: 16th largest constellation
- Area: 804 square degrees
- Neighboring constellations: Cepheus, Draco, Lacerta, Lyra, Pegasus, and Vulpecula.
Objects of Interest in Cygnus
Cygnus contains a spectacular galaxy known as the Fireworks Galaxy (NGC 6946), as well as a number of interesting nebulae. These include the Pelican Nebula (IC 5070), the North America Nebula (NGC 7000), the Crescent Nebula (NGC 6888), and the famous Veil Nebula that is so big that various parts of it have their own NGC designations. Two meteor showers, the October Cygnids and the Kappa Cygnids, are associated with the constellation.
Apart from the beautiful double star Albireo, the constellation only contains two Messier objects, both of which are open clusters, and visible with modest amateur equipment. Below are some details:
Messier 29 (M29, NGC 6913), located relatively close by at a mere 4,000 light years distant, has an apparent visual magnitude of 7.1, making it an easy target for binoculars. M29 is also relatively young, being only about 10 million years old. The most luminous star in the little cluster has an apparent magnitude of 8.75, and the five hottest stars are all B0-type stars. Look for the cluster roughly 1.7 degrees southeastward of the star Gamma Cygni.
Messier 39 (M39, NGC 7092), located about 800 light years away, was discovered by Messier in 1764 and is estimated to be between 200-300 million years old, which puts it in the intermediate age bracket for clusters of this type. Having an apparent visual magnitude of 5.5, all the observed stars in the cluster are still on the main sequence, although the brightest stars in the cluster are expected to begin their transition into the red giant phase within the next several million years or so. Look for the M39 about 2.5 degrees to the southward of the star Pi-2 Cygni.
Lyra Constellation
Lyra may be among the smallest constellations, but it has a unique claim to fame and therefore deserves its place on this list of prominent summer constellations. It contains the star Vega, which is not only its brightest star, but also the second most luminous star in the northern hemisphere, and the fifth brightest star in the entire night sky overall.
Moreover, Vega is the first star after the Sun to have its picture taken, and its spectrum recorded which happened in July of 1850, and August of 1872, respectively. Another star of interest in Lyra is Epsilon Lyrae, a multiple-star system also referred to as “The Double Double.”
Quick Lyra Facts
- Constellation: Lyra
- Coordinates: Between latitudes +90° and -40°
- Best seen: 21:00 (9 p.m.) Local Time during the month of August
- Brightest star: Vega (Alpha Lyrae) – Apparent magnitude 0.03
- Stars with planets: 9
- Size: 52nd largest constellation
- Area: 286 square degrees
- Neighboring constellations: Cygnus, Draco, Hercules, and Vulpecula
Objects of Interest in Lyra
Lyra contains several objects of scientific interest. These include NGC 6745, a trio of galaxies that are caught in a violent merger, and the beautiful open star cluster NGC 6791. Three meteor showers, the Lyrids, the June Lyrids, and the Alpha Lyrids, are associated with the constellation.
Messier objects of interest for amateur stargazers include the Ring Nebula (M57), a planetary nebula with a white dwarf at its center. Lyra also contains Messier 56 (M56, NGC 6779), a globular cluster located about 33,000 light years away that is 13.7 billion-year-old and stretches across a full 84 light-years of space. The most luminous stars in the cluster are all about 13th magnitude, and it contains about a dozen or so known variable stars.
