Scorpius is by far one of the most easily recognizable constellations in the night sky. It is also one of the most prominent constellations of the zodiac, and has been known since ancient times. The 2nd Century Greek astronomer Ptolemy had a catalogue of the constellations formally recognized during that era. Scorpius is definitely one of them, and features throughout many other cultures and historical records, even pre-dating the Greeks and Ptolemy’s catalogue.
Scorpius can be seen in most parts of the world, but it actually lies south of the celestial equator and quite close to the centre of the Milky Way galaxy. This makes it harder to see very far North, but visible for several months to southern observers.
The constellation has the distinct shape of a scorpion, which it represents. Scorpius houses many bright stars – including the one of the brightest in the night sky – the red star Antares found at its centre. The star’s red hue is so that its name literally means “Rival of Mars”.
How To Locate Scorpius
Scorpius is probably one of the easiest constellations to find. It is a very large constellation, has many bright stars and a distinct scorpion-like shape. You will find the constellation Libra to the west of Scorpius and Sagittarius to the east. July and August are generally the best months to view Scorpius in the Northern Hemisphere.
For most northern latitudes in the states, Scorpius never climbs high in the sky but appears to just be skirting along the horizon. You will need a good unobstructed view of the south to see the full constellation. And of course, the further north, the less of the constellation you can see. Indeed, the tail does stay partially hidden below the horizon for most of its appearance in the extreme northern latitudes, but the brilliant star Antares remains steadily visible as far north as southern Alaska.
The constellation can easily be seen from March to October in the Southern Hemisphere, where it is ideally located.
Scorpius Mythology and History
Scorpius is the Latin for scorpion. In both Roman and Greek history, the mythology of Scorpius is closely linked to the mythology of Orion the Hunter. The story goes that Orion, a strong but somewhat arrogant huntsman, proudly boasted to goddesses Artemis and Leto that he was cable of killing any animal on Earth.
Gaia, goddess of the Earth, protected animals and did not take kindly to Orion’s boastful threat. She sent the scorpion to deal with Orion, during the battle between the man and beast, Orion was killed by the scorpion. The rest of the myth goes that Zeus placed Scorpius on the opposite side of the sky from the Orion. Other variations of the myth tell of different motives for Artemis sending the scorpion to kill Orion, and still others have Artemis herself slay the hunter.
The Babylonians recognized the constellation dating back 3000 years, and called it MUL.GIR.TAB which translates to ‘Scorpion’. The literal translation can be read as ‘creature with a burning sting’.
There are ancient Babylonian and Arabic descriptions of the Scorpius in which the constellation Libra is treated as the scorpion’s claws rather than as its own independent constellation.
In spite of the constellations distinct shape as we know it in modern/ Western astronomy, there are old cultures which recognize Scorpius as something else. In Indonesia, the constellation is called Banyakangrem, a swan; and also sometimes called Kalapa Doyong, meaning a leaning coconut tree.
In Hawaii, Scorpius is associated with the Big Fishhook of Māui.
Stars in the Constellation Scorpius
Scorpius is home to several bright stars. The constellation has almost a dozen stars all below magnitude 3.
- Antares/ Alpha Scorpii: Antares is the brightest star in the constellation Scorpius. Its dusty red hue is obvious even to the unaided eye, and is often compared to Mars thanks to its distinct color, brightness and apparent size. It is one of the brightest stars in the night sky. Antares is commonly known as both the rival of Mars and the heart of the scorpion. Antares is a slow and irregular variable star fluctuating between magnitudes 0.6 and 1.6 approximately. It is also a binary star system lying some 550 light years from the Solar System. The primary of the pair is a red supergiant star with a diameter well over 850 times that of the Sun.
- Shaula/ Lambda Scorpii: Despite its designation as Lambda Scorpii, Shaula is actually the second brightest star in Scorpius. It is part of a triple star system located about 600 light years from the Solar System. Along with another star Lesath, the two have the informal nickname “Cat’s Eyes”. This is due to their close proximity to one another and their brightness.
- Sargas/ Theta Scorpii: Sargas is a white giant star, approximately 25 solar radii large (25 R☉). The giant star lies about 300 light years from Earth.
- Dschubba/ Delta Scorpii: Dschubba is a multiple star system. Currently, astronomers are sure that it is a triple star system, but it is possible that it could be a 4-star system. Delta Scorpii’s primary star is a blue giant. The star is approximately 15 solar masses.
- Graffias/ Acrab/ Beta Scorpii: Beta Scorpii appears to be a binary star, but closer observations of the star revealed that it is actually a multiple star system made up of six stars. The name Graffias is the Italian for the “claws”. The star’s other traditional name Acrab, is Arabic for the “Scorpion”.
- Al Niyat/ Sigma Scorpii: Another multiple star system in Scorpius, Sigma Scorpii is comprised of a group 4 stars located about 700 light years from the Solar System. The multi-star system has a combined apparent magnitude of 2.88. Like the multi-star system in Delta Scorpii, Sigma’s primary is also a blue giant star. This blue giant has a diameter around 12 or 13 times that of the Sun. Sigma Scorpii’s traditional name, Al Niyat is also not unique to the system. Another star in the constellation, Tau Scorpii, is also called Al Niyat. The star’s traditional name comes from the Arabican-niyāţ, meaning “the arteries” of the scorpion’s heart.
- Lesath/ Upsilon Scorpii: This is a blue sub-giant star. Its surface temperature is around 4 times hotter than the Sun, and it lies around 600 light years from Earth. The name Lesath comes from an Arabic phrase which roughly translates to “bite of a poisonous animal.”
- Jabbah/ Nu Scorpii/ 14 Scorpii: Nu Scorpii is another multiple star system in the constellation, this time comprised of two close groups of stars. The system lies well over 400 light years from Earth and contains a mix of stars including sub-giants and main sequence dwarf stars. Nu Scorpii illuminates the reflection nebula IC 4592.
- Al Niyat/ Tau Scorpii: Tau Scorpii is the other star in Scorpius known as Al Niyat. It is a hot, main sequence dwarf star about 15 times more massive than the Sun, over 18,000 more luminous, and a radius around 6 times that of the Sun. The star has an apparent magnitude of 2.82. Tau Scorpii lies almost 500 light years away and is a popular target for astronomers. This is due in part to how hot and luminous it is, but mainly because of the star’s strong and clear spectrum due to its slow rotation.
- U Scorpii: U Scorpii is a very interesting star. In astronomy, a nova is an event that causes the sudden appearance of an extremely luminous and apparently “new” star. These novae are usually old dwarf stars that suddenly flare up, becoming brilliantly bright before fading again over several weeks. There are several things that can cause this, such as a companion star accreting matter onto a dwarf until a sort of nuclear ignition occurs. U Scorpii is one of only a dozen or so known recurring nova in the Milky Way: stars that go through this nova event a number of times. It is also the fastest known nova. Its last eruption was seen in 2010, while the next eruption is expected sometime next year in 2020.
- HD 159868: This is a yellow dwarf star about 170 light years from Earth. It is of particular interest because it homes two exoplanets. One was discovered in 2007 and is thought to be a gas giant, while the other was discovered in 2012.
- Scorpius X-1: Scorpius X-1 is a binary star system about 9,000 light years from Earth. It is a historically significant star as it was the first X-ray source detected beyond the Solar System, and the strongest X-ray source in the sky second to the Sun. It was discovered by a team of researchers in 1962. The astrophysicist who led the team, Riccardo Giacconi, laid the foundations of X-ray astronomy and won a Nobel Prize for his work in 2002.
Deep Sky Objects in the Constellation Scorpius
Scorpius’ location against the backdrop of the Milky Way, close to the galactic centre, makes it quite rich in deep sky objects, including some wonderful Messier objects which can be seen with the naked eye.
- Messier 4 (M4)/ NGC 6121: M4 is one of the closest globular clusters to the Solar System, lying some 7,200 light years away. The entire cluster is approximately 75 lights years across. M4 is also historically significant as it was the first cluster in which the individual stars were resolved. Like the majority of globular clusters, M4 is very old, about 12.2 billion years old! M4 has an apparent magnitude of 5.9, placing it just within naked eye reach and making it an especially lovely target to view through binoculars and small telescopes. A good pair of binoculars is an especially good choice for viewing clusters thanks to their wide field of view. Look for M4 west of Scorpius’ brightest star Antares.
- Butterfly Cluster/ M6/ NGC 6405: Another beautiful cluster in Scorpius perfect for scanning with binoculars is the open cluster M6; more commonly known as the Butterfly Cluster due to its flared out and almost symmetrical shape through a telescope. The cluster was discovered by the Italian astronomer Giovanni Batista Hodierna in 1654. Most of the stars in the cluster are very hot, B-type stars. These are main sequence stars – like the Sun – but bigger, hotter and more luminous. Most of the stars are also very young, only about 100,000 million years old. One of the exceptions is the brightest star in the cluster, BM Scorpii (HD 160371), an orange giant. The cluster is magnitude of 4.2, so it stands out nicely on a dark night. Binoculars are a good choice for viewing the cluster, though you may only resolve a dozen or so of the cluster’s 300+ stars. A small telescope will reveal up to 80 stars. You can find the cluster in the region of stars that make up in the constellation’s stinger.
- Ptolemy Cluster/ M7/ NGC 6475: M7 is an open cluster, also called the Ptolemy Cluster after the 2nd century astronomer who discovered it in 130 AD. At magnitude 3.3, the cluster is easily visible to the naked eye, and another great target with binoculars and small telescopes. The cluster bears a slight resemblance to the Pleiades, and includes about 80 young stars of around 200 million years old. The entire cluster has a radius of about 25 light years.
- Messier 80/ NGC 6093: M80 is a globular cluster in the Northern Skies, sometimes dubbed a rival or counterpart to the southern globular cluster (and biggest in the Milky Way) Omega Centauri. Globular clusters are usually very old, and contain stars that are billions of years old. M80 has a surprising number of young, massive stars – twice as many as what is typical for most globular clusters. The cluster houses hundreds of thousands of stars, all densely crammed a space less than 100 light years across. This places M80 among the most populated globular clusters in the Milky Way. M80 has an apparent magnitude of 7.87, so it is an ideal target for small telescopes and binoculars You can find M80 wedged about half way between Antares and Acrab. A supernova observed in the late 19th century when the star T Scorpii went supernova, Nova 1860 AD, was located in M80.
- Cat’s Paw Nebula/ Bear Claw Nebula/ Gum 64/ NGC 6334: If you are on the hunt for some deep sky objects, the Cat’s Paw Nebula is a good stop in Scorpius. It is only 50 lights away. The emission nebula is home to some 10,000 stars in total. Most of the stars in this in the nebula are newly formed, massive stars which illuminate the nebula. It is best viewed though medium sized telescopes with a special filter for viewing nebulae.
- Butterfly Nebula/ Bug Nebula/ NGC 6302/ Caldwell 69: the Butterfly Nebula is a planetary nebula almost 4000 light years away from Earth. Planetary nebulae are the result of giant, ageing stars blowing off their outer layers of gas and other materials. This particular planetary nebula was created from red giant star shedding its outer shells in a process that continued for over 2,000 years. It is structurally complex and spans about 2 lights across. The nebula’s overall magnitude is 7.1.
- War and Peace Nebula/ NGC 6357: This diffuse nebula gets its fascinating name from its slight resemblance to a human skull on the eastern half, and a dove on the western half when viewed in infrared light. The nebula contains many young stars and also the open cluster Pismis 2.
Scorpius Meteor Showers
The main meteor shower in Scorpius is the Alpha Scorpiids which roughly occurs between April 21st and May 26th. The shower usually peaks around May 15th every year. Antares is the closest star to the radiant point.
The Alpha-Scorpiids is a faint meteor shower with a Zenith Hourly Rate (ZHR) of 3 -5. That just means that you will only see about 3 – 5 meteors per hour radiating from that point in Scorpius. This number can sometimes increase, though not very dramatically.