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 2015 it has had six stars with confirmed planets discovered within its boundaries.
The son of Zeus and Danaë, Greek mythological hero Perseus has a whole host of legends associated with him, and can be found in the celestial heavens surrounded by a family of constellations with related legends. These 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.
The constellation’s second brightest star is called Algol, which appears red in the night sky, but is actually a triple star system composed of two blue and one orange-red star. 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 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.
There are plenty of other interesting stars in Perseus, too, including one of Algol’s component stars (sub-giant), as well as Zeta Persei (super giant), Gamma Persei (giant yellow star), Gorgonea Tertia (red giant), Zeta Persei (blue super giant), Nash (orange giant), and more.
Deep Sky Objects
There are lots of Deep Sky objects (star clusters, nebulae and galaxies) here, too, such as the Alpha Persei Cluster, which is visible to the naked eye as a cluster of blue stars which are very young at just 60 million years old. 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 kilometers per second.
You can also find Messier 34, Messier 76, the California Nebula, and NGC 1333 floating about. 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. The California Nebula is eponymously named because it is shaped like the state of California. NGC 1333 is interesting because it is a Reflection Nebula. What this means is that its own stars are too weak to ionize the gas and make it glow (making it an Emission Nebula). 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 largest supernova ever recorded by modern scientists, being more than one hundred times more powerful than a typical supernova.
Perseid Meteor Shower
Perseus has one of the better meteor showers of any constellation in the sky. The Perseids occurs during a nice warm time of the year in the northern hemisphere, so many people take the time to go and have a look. It’s quite protracted, starting around the middle of July and building to its peak approximately August 10. It usually provides about one or two meteors per minute, or 60 to 100 meteors per hour.
But that’s not all, there’s also a minor shower following close on its heels called the September Perseids. Although called a minor shower, it has been known to produce some really interesting displays, and 2015 is looking rather promising, too, so it might be worth paying attention on September 9th when it peaks because we’ll only have a little sliver of Moon so whatever it produces should be quite visible.