Scorpius is a constellation known for its distinctive shape and for being one of the 13 constellations of the zodiac, a belt-shaped area of the night sky that the sun, moon, and planets appear to pass through.
It is one of the brightest constellations in the night sky. The name is Latin for scorpion, or literally translated as the "creature with the burning sting."
Where is the Scorpius constellation?
You can see all or some of Scorpius from the Southern Hemisphere and much of the mid-Northern Hemisphere between May and August. While it appears high in the sky in the center of the Milky Way in the Southern Hemisphere, it is close to the southern hemisphere in places where it is visible in the Northern Hemisphere. Because of its unusual shape and relative brightness, Scorpius is not difficult to spot. In either hemisphere, the best time to view the constellation is July and August, and it is at its highest point around 9 pm in mid-July, according to EarthSky.
How many stars does Scorpius have?
Scorpius has 18 named stars, including Antares, the so-called "rival of Mars," a red giant star named for its bright hue, and Shaula and Lesath, sometimes called the "Cat's Eyes" because they are so close together. It also has 14 stars known to have planets orbiting them. One of these, PSR B1620-26 b, is nicknamed "Methuselah" because of its extreme old age. It's estimated to be 12.2 billion years old, plus or minus a billion years (for comparison, the universe is estimated to be about 13.8 billion years old). The constellation is also home to potentially habitable planets, including some orbiting the red dwarf star Gliese 667C.
Related: Night sky: What you can see tonight [maps]
Scorpius constellation observing targets
Because of its location near the center of the Milky Way, Scorpius has many interesting objects to observe, including stars, open and globular clusters, and nebulas. Though some are visible with the naked eye, most benefit from some amount of magnification to view clearly, from a good pair of binoculars to a small or medium-sized telescope. If you need equipment, our best binoculars and best telescopes guides may help.
Jargon buster
Magnitude: An object's magnitude is a measure of how bright an object appears from Earth. Brightness is measured on a numbered scale, with lower numbers being brighter than higher numbers. And it even goes negative!
Right ascension (RA): Right ascension is the sky's equivalent to longitude on Earth, and it helps astronomers locate celestial objects. It covers the east-west direction and is measured in hours, minutes and seconds.
Declination (Dec): Declination also helps astronomers locate celestial objects in the sky — it is akin to latitude on Earth. It marks how high an object will rise in the sky, covering the north-south direction in units of degrees, arcminutes and arcseconds (60 arcseconds in an arcmin, 60 arcmins in a degree).
Bug Nebula
Magnitude: 9.1
Approximate distance from Earth: 3,400 light-years
Location: 17h 13m 44.63s (right ascension), -37° 06' 11.3" (declination)
Also known as NGC 6302, Caldwell 69, or the Butterfly Nebula, you can view this object's gorgeous "wings" with a pair of 80-mm aperture binoculars or a small telescope, according to The Sky Live.
Named for its bug or butterfly-like shape, it is a planetary nebula, formed when a dying red giant star ejects its outer layers, creating a shell of glowing gas. The Bug Nebula is also called a bipolar planetary nebula because of its butterfly or hourglass-like shape, which happens when material is funneled towards the poles of the dying star, according to NASA.
Butterfly Cluster
Magnitude: 4.2
Approximate distance from Earth: 1,590 light-years
Location: 17h 40m 20.7s (right ascension), -32° 15' 15" (declination)
This open cluster of stars, also called NGC 6405 or Messier 6, bears a much more vague resemblance to the shape of a butterfly. This cluster was formed from a giant cloud of gas and dust between 50 and 100 million years ago, according to NOIRLab.
Most of its bright stars are hot, blue stars with masses between four and five times that of our sun, but its brightest star is an orange giant, BM Scorpii, according to Messier-Objects.com. In an area with dark skies, the Butterfly Cluster is just barely visible with the naked eye, but more clearly viewed using a pair of binoculars, according to The Sky Live.
Ptolemy's Cluster
Magnitude: 3.3
Approximate distance from Earth: 980 light-years
Location: 17h 53m 51.2s (right ascension), -34° 47' 34" (declination)
Officially NGC 6475 or Messier 7, this open cluster can easily be seen with the naked eye or with binoculars. Because of its location at the southern tip of Scorpius, it can be hard to spot in the Northern Hemisphere, since Scorpius often does not rise all the way above the horizon. In these areas, the best time to view it is in the summer, when Scorpius reaches its highest height.
It has been known since antiquity and is one of the objects cataloged by the Greek astronomer and mathematician Claudius Ptolemy in the second century. The cluster has around 80 stars, according to Messier-Objects.com.
Messier 4
Magnitude: 5.4
Approximate distance from Earth: 6,300 light-years
Location: 16h 23m 35.40s (right ascension), -26° 31' 31.9" (declination)
One of several objects sometimes called the "Cat's Eye," Messier 4, or NGC 6121, is the closest globular cluster to Earth, according to NASA. It can even faintly be seen with the naked eye but is more easily seen with binoculars or a small telescope, and is near the red giant Antares, one of the brightest stars in the sky.
Unlike open clusters, globular clusters like this one contain stars that formed at many different times, held together with gravity and with more stars concentrated at their centers. Messier 4 contains over 100,000 stars, including 40,000 white dwarfs. These are the ancient remnants of stars that have expelled their outer layers. Messier is home to some of the oldest astronomical objects known, such as the exoplanet "Methuselah," and could be up to 13 billion years old, according to NASA.
Messier 80
Magnitude: 7.3
Approximate distance from Earth: 28,000 light-years
Location: 16h 17m 02.51s (right ascension), -22° 58' 30.4" (declination)
One of the densest globular clusters in the Milky Way, this globular cluster contains hundreds of thousands of stars, as per NASA. You can use a small telescope to spot it, and like much of Scorpius, it is the most clearly visible in July. In 1860, observers recorded a nova in this cluster, which can happen when a white dwarf collects gas from a nearby star, reigniting the fusion process that it has long since exhausted. Messer 80 is also known for having an usual amount of stars that are far younger and more massive than most of its other stars.
Meteor showers and recurring events
Two meteors showers, the Alpha Scorpiids and the Omega Scorpiids, are associated with Scorpius, and are so named because they appear to radiate from the stars Alpha Scorpii (Antares) and Omega Scorpii, respectively. The Alpha Scorpiids happen every year between May 1 and 31, according to the Custer Observatory. It peaks around May 16. On average, five meteors are visible per hour during the shower's peak.
The Omega Scorpiids takes place between May 23 and June 15, according to the Custer Observatory. They are divided into two showers — the North and South Omega Scorpiids, depending on which hemisphere they are seen from, and peak around June 2. Their peak rate is about five meteors per hour.
Scorpius is home to the b star U Scorpii, a recurrent nova and the fastest known nova, which experiences eruptions, or flares in brightness, about every ten years. Its most recent eruption was in 2022, according to the American Association of Variable Star Observers.
Scorpius Q&A with an expert
Ashley Pagnotta is an assistant professor at the College of Charleston. Pagnotta's research interests include observational astrophysics of novas, supernovas and other variable stars.
Where is U Scorpii?
U Scorpii, also known as U Sco, is located in the constellation Scorpius, up near the top left pincer claw, as you're looking at the constellation in the sky.
Two separate — but very close — stars make up the system we call U Sco, and usually they are much too faint to see with the unaided eye. Approximately every ten or so years, however, an eruption called a recurrent nova occurs on the surface of one of the stars and the system brightens dramatically. Even at peak brightness, it's not quite visible to the human eye, but is easily within the range of most binoculars (not to mention telescopes), especially from a dark viewing site.
What is a recurrent nova?
A nova is an eruption that occurs on the surface of a white dwarf in a double (or binary) star system. A white dwarf is essentially the ember of a dead star — it's the hot, dense, leftover remnant of a low-mass star that has run out of fuel to sustain nuclear fusion. With no available fuel left, fusion ceases and the star is no longer continuously producing energy.
If the white dwarf is in a binary star system, and if the other star in the binary is close enough, the white dwarf can gravitationally pull hydrogen gas from the outer layers of the companion star onto its surface. The gas builds up in a layer on the surface of the white dwarf until it gets hot and dense enough at the base of that layer for runaway hydrogen fusion to ignite.
The fusion of all of that hydrogen releases a massive amount of energy, causing the system to quickly get much brighter, which is what we call a nova! In most stars, this only occurs once every 10,000 or so years, but in some special systems, the nova eruptions happen much more frequently, recurring on a timescale of less than about 100 years, hence the name recurrent nova.
What causes U Scorpii's eruptions?
U Sco's eruptions are caused by the process described above, but because of some particular conditions in the system, they happen very frequently and pretty regularly, about once every ten years.
The U Sco system consists of a very massive white dwarf and a companion star that is starting to move through the end stages of its life. There are two key things happening there.
One, the conditions on the surface of a high-mass white dwarf like U Sco's are such that less hydrogen gas needs to accumulate before a nova eruption is triggered, and two, as the companion star evolves, it slowly expands, which causes the rate of hydrogen transfer between the two stars to be higher than usual.
So less mass is required to cause the eruption and that mass is accumulating faster than normal, so there are more frequent eruptions. Because the mass of the underlying white dwarf likely does not change much during a single eruption and because the mass transfer rate is also relatively constant, the amount of time for the necessary mass to accumulate is pretty consistent, and thus so is the time between eruptions.
How is U Scorpii different from other recurrent novas?
U Sco has the shortest known recurrence time of any recurrent nova in our Milky Way Galaxy, and the second-shortest of all known recurrent novae. (There is a system in the nearby Andromeda Galaxy that recurs about once a year!) Because of its short recurrence time and relatively predictable time between outbursts, we have been able to study it in great detail with many different telescopes and at many different wavelengths, especially during its 2010 and 2022 outbursts. This has led to a better understanding of recurrent novae in general, as well as the discovery of some unexpected, and still unexplained, effects.
Scorpius mythology
Scorpius and Orion are often intertwined in Greek mythology. According to one myth, Orion boasted that he would kill every animal on the earth. The goddess-hunter Artemis and her mother, Leto, dispatched a scorpion to kill Orion. Zeus put the scorpion in the heavens after it won the battle. In another myth, the god Apollo, Artemis's twin brother, grew angry and sent a scorpion to attack Orion because he claimed to be a better hunter than Artemis. Zeus put Orion and Scorpius in the sky, but they are visible at different times of the year.
In astrology, which is not a science, the constellation is called Scorpio. It is the eighth sign in the Zodiac and represents those born between Oct. 24 and Nov. 22. The traits of those born under the sign are said to include determination and loyalty.
Scorpius is not a scorpion to everyone. The Javanese people of Indonesia call this constellation Banyakangrem, meaning "the brooded swan" or Kalapa Doyong, meaning "leaning coconut tree." In Hawaii, it is known as the demigod Maui's Fishhook. In Chinese mythology, the constellation was part of the Azure Dragon.
Additional resources
Explore Scorpius in spectacular detail in this photograph published on NASA. Learn more about the South Omega Scorpiids meteor shower with these resources from UniverseGuide.com. Read more about the Scorpius constellation and how you can see it in the summer sky with these resources from the National Science Teaching Association.
Bibliography
Messier Objects (2015a). Messier 6: Butterfly Cluster | Messier Objects. [online] www.messier-objects.com. Available at: https://www.messier-objects.com/messier-6-butterfly-cluster/[Accessed 26 Jul. 2023].
Messier Objects (2015b). Messier 7: Ptolemy’s Cluster. [online] Messier Objects. Available at: https://www.messier-objects.com/messier-7-ptolemys-cluster/
Garner, R. (2023). Messier 80. [online] NASA. Available at: https://www.nasa.gov/feature/goddard/2017/messier-80 [Accessed 26 Jul. 2023].
NOIRLab (2020). M6, NGC 6405; Butterfly Cluster. [online] www.noirlab.edu. Available at: https://noirlab.edu/public/images/noao-02637/[Accessed 26 Jul. 2023].
McClure, B. (2023). EarthSky | Scorpius? Here’s your constellation. [online] earthsky.org. Available at: https://earthsky.org/constellations/scorpius-heres-your-constellation/ [Accessed 26 Jul. 2023].
Popering, D. van (n.d.). Custer Institute. [online] www.custerobservatory.org. Available at: https://www.custerobservatory.org/meteors.html [Accessed 26 Jul. 2023].
theskylive.com. (n.d.). Messier 6 (Butterfly Cluster) - Open Cluster in Scorpius | TheSkyLive.com. [online] Available at: https://theskylive.com/sky/deepsky/messier-6-butterfly-cluster-object [Accessed 26 Jul. 2023].
theskylive.com. (n.d.). NGC 6302 (Bug Nebula) - Planetary Nebula in Scorpius | TheSkyLive.com. [online] Available at: https://theskylive.com/sky/deepsky/ngc6302-bug-nebula-object[Accessed 26 Jul. 2023].
www.aavso.org. (n.d.). U Sco reported in outburst | aavso. [online] Available at: https://www.aavso.org/u-sco-june-2022 [Accessed 26 Jul. 2023].
Join our Space Forums to keep talking space on the latest missions, night sky and more! And if you have a news tip, correction or comment, let us know at: community@space.com.
