Perseus is visible to observers located between +90° and −35° lattitude, and can be seen in the Northern hemisphere from August to March, and in the Southern hemisphere during spring and early summer. It is the 24th biggest constellation in the night sky, and its brightest star, Mirfak, is a yellow-white supergiant 592 light years away that shines with an apparent magnitude of 1.8, making it the 35th brightest star in the entire sky. Being located along the Milky Way, Perseus has many interesting stars and deep sky objects to explore, and as of 2017 it has had seven stars with confirmed planets discovered within its boundaries.
As the son of Zeus and Danaë, Perseus was one of Greek mythology’s most celebrated heroes, and had a whole host of legends associated with his adventures. Likewise, the constellation of Perseus can be found in the celestial heavens surrounded by a family of other constellations closely associated with his exploits. This include his wife, Andromeda, as well as his murderous in-laws, Cepheus and Cassiopeia, who left their daughter Andromeda chained to a rock so Cetus, the Sea Monster, could kill her instead of destroying their city. Also nearby is faithful Pegasus, the legendary winged horse who served Perseus and Andromeda all his mortal life.
– Mirfak (Alpha Persei), the constellation’s brightest star, is a blue-white supergiant situated 592 light years away that shines with a visual magnitude of 1.806. It is about 7.3 times more massive than the Sun, 60 times bigger, and around 5,000 times more luminous. The star Mirfak is also known as Algenib, with their names derived from the Arabic for “elbow” and “flank” respectively.
– Algol (Beta Persei), the second brightest star in Perseus, appears red in the night sky, but is actually a triple star system composed of two blue and one orange-red stars. The system is located 92.95 light years away and shines with an apparent magnitude of 2.09, making it the 60th brightest star in the entire night sky. Algol is also a very well-known star as it was the first-discovered eclipsing-binary, and every couple of days it dims to a magnitude of 3.4 before returning back to being bright again.
Historically, Algol seems to have been equally despised or feared by everyone who ever put a name to it. It was known as Satan’s Head to the Hebrews, Tseih She (Piled Corpses) to the Chinese, and in skylore is associated with the Gorgon Medusa, who had snakes instead of hair and could turn a person to stone with a single glance. The Arabs also called it the “Demon Star”, and the word Algol is actually derived from their name for it – ra’s al-ghul (Head of the Ogre), which incidentally is also the name of the supervillian in the DC comics who heads the League Of Assassins.
– Atik (Zeta Persei), the constellation’s third brightest star, is a blue-white supergiant located 750 light years from our solar system with a magnitude of 2.86. It has around 27 times our sun’s radius, 16 times its mass, and about 47,000 times its luminosity.
There are plenty of other interesting stars in Perseus, too, including Gamma Persei (giant yellow star), Gorgonea Tertia (red giant), Zeta Persei (blue super giant), Nash (orange giant), and more.
Notable Deep Sky Objects
There are lots of notable deep-sky objects (star clusters, nebulae and galaxies) in Perseus to enjoy, such as the Alpha Persei Cluster, which is visible to the naked eye as a group of blue stars, and at just 60 million years old is astronomically speaking very young . Another is Caldwell 14, sometimes called simply The Double Cluster, which is less than 13 million years old and despite presently being 7,500 light years away is also heading right for us at a rate of 22 kms per second.
You can also find Messier 34, Messier 76, and the California Nebula (NGC 1499), in this constellation. Messier 34 is an open cluster with 400 stars, and it is just barely discernible with the naked eye in pitch dark conditions with no Moon; Messier 76 is a planetary nebula found 2,500 light-years away which is also known as the The Little Dumbbell Nebula because it resembles the Dumbbell Nebula (M27) in Vulpecula; and the California Nebula is eponymously named after the state of California, whose shape it is said to resemble.
Perseus also contains an interesting Reflection Nebula called NGC 1333. What this means is that its own stars are too weak to ionize the gas and make it glow (making it an Emission Nebula), and instead, its illumination is dependent on the surrounding stars. Typically its gas has a great deal of carbon in it, in the form of diamonds, which makes it very reflective. In addition, it usually has very high levels of iron, the particles of which align themselves with the galactic magnetic field, which in turn causes the light to be polarized.
Of course the most frequent visual target in Perseus is NGC 1260, a spiral galaxy containing one of the brightest stellar objects we’ve ever seen, the remnants of supernova SN 2006g. On September 18th, 2006, in a galaxy 240 million light-years distant astronomers detected what turned out to be the second largest supernova ever recorded by modern scientists, being more than one hundred times more powerful than a typical supernova.
Perseid Meteor Shower
Perseus boasts one of the most impressive meteor showers of any constellation, The Perseids, which occur during a nice warm time of the year in the northern hemisphere, thus encouraging many people to go outside and take a look. It’s quite protracted, lasting from around July 17th to August 24th, and peaking around August 9-13th when about one or two meteors per minute, or 60 to 100 meteors per hour can be seen.
But that’s not all, there’s also a minor shower following close on its heels called the September Perseids, which takes place between September 5th and 17th, with a peak on the 9th of around 3 meteors per hour. Although called a minor shower, it has been known to produce some really interesting displays, so don’t forget to give Perseus’ lesser know meteor shower due attention. Interestingly, although The Perseids and the September Perseids seem to appear from the same radiant, the two showers are separate and are formed from different comets.