Lyra, the harp, is a small constellation with a very recognizable shape. It is one of the few constellations that actually resembles the object for which it is named. Lyra is located between Hercules and Cygnus, and is best seen from May through November.
Lyra includes the brilliant star Vega, one of the brightest stars in the northern hemisphere's summer skies. Below Vega is a parallelogram formed by four 3rd-magnitude stars.
History and Mythology
Several myths exist about the origins of Lyra. It was said that Apollo was pleased by the music of the lyre, which was invented by Mercury. While walking along a beach, Mercury found a tortoise shell, and put string through its holes. He found that the shell made beautiful music.
Another myth tells us that when Orpheus' wife Eurydice died from a snake bite, he went into the underworld to beg for her return. He played his lyre for Hyades, who agreed to return Eurydice, on the one condition that Orpheus could not look at her as they traveled to the outer world. But as they approached the surface of the Earth, he turned to see if Eurydice was following him. She slipped back to the land of the dead forever. Orpheus soon died of a broken heart, and his lyre is now among the stars.
Notable Stars
Alpha Lyrae, the harp star, is commonly known as Vega. This name comes from an Arabic word "waqi" that means "vulture". In ancient Egypt and India, the constellation Lyra was represented as a vulture.
Alpha Lyrae is a brilliant, blue-white star 25 light-years away, and it is the 5th brightest star in the sky. It is three times larger than our Sun, and 60 times more luminous. Vega was the first star to be photographed in the 1850's. It was also one of the first stars to have a proto-planetary dusk disk discovered orbiting around it, by the IRAS satellite in 1983. This discovery was inspiration for Vega's role as the home to an extraterrestrial civilization in the famous science fiction movie, "Contact."
Around 10,000 BC Vega was the North Pole Star. It will be the pole star again in AD 14,500. Vega, Deneb in Cygnus, and Altair in Aquila form the Summer Triangle.
Beta Lyrae is traditionally named Sheliak, which is Arabic for "tortoise" or "harp." Located 880 light-years away, it is the prototype for the class of eclipsing binaries whose components are so close together that they deform each other by their mutual gravitation. Beta Lyrae's apparent magnitude changes from +3.4 to +4.6 over a period of 12.9 days.
The variable star R Lyrae is a red giant, changing between magnitude 3.9 and 5.0 over a 46 day period. Unlike Sheliak, it varies because of internal processes, not eclipses. Another fainter variable in Lyra, confusingly named RR Lyrae, is the prototype of an entire class of variables called RR Lyrae stars. These stars pulsate in a manner similar to Cepheid variables, but have shorter periods and lower luminosities. They are important "standard candles" used to measure distances to objects in the Milky Way, especially globular clusters.
Epsilon Lyrae is famous a quadruple star system known as the "Double Double". It is easily separated with binoculars into two stars of magnitudes 4.8 and 5.1. Each star, in turn, is a double system. Use a good telescope with high magnification to see its pairs, which are separated by 2.3 and 2.9 arcseconds.
Clusters, Nebulae, and Galaxies
The most famous deep sky object in Lyra is M 57, the Ring Nebula. It lies midway between the two lower stars in the parallelogram of Lyra. It is a 9th magnitude planetary nebula, which looks like a smoke ring or a pale donut. For a good view, use a 4 inch or larger telescope at a magnification of 200x.
The Ring Nebula is often regarded as the prototype of all planetary nebulae. These objects are the remains of sunlike stars which have blown away their outer envelopes, leaving planet-sized white dwarfs at their centers. The distance to M 57 is not very well known; estimates range from 1,400 to 4,100 light years. The current estimate is 2,300 light-years, making its physical size about one light year in diameter.
M 56 is a 9th magnitude globular cluster about 33,000 light-years away. It is clearly seen in an 8 inch telescope. NGC 6791 is an 11th magnitude open cluster located near the eastern edge of Lyra. It contains only about 20 stars, and it is about 17,000 light-years away. There are no prominent galaxies in Lyra.