Blue Planet Project

May to July Sky School
 


To start finding this month's featured constellations, find the Big Dipper.

Perhaps the easiest shape to pick out is the Northern Crown, Corona Borealis, with its nice little arc of stars centred on Alphecca, also known as Gemma, the gem of the crown.  To find it, run off the end of the Big Dipper's handle, toward the south-eastern horizon, by about the length of the handle.

From there you can find Bootes, the Herdsman, sitting between the Crown and the Big Dipper's handle.  The brightest star in Bootes, yellow-coloured Arcturus, is easy to find. It is the fourth-brightest star in the sky, and certainly the brightest in a large area of sky south-east from the tip of the handle.  Once you have found Arcturus, which marks Bootes' hip, you can follow the rest of Bootes' body and head.

On the other side of the Crown, to the East, find Hercules.  It can be hard to trace Hercules.  Like the Greek hero it's named for, Hercules is large and rather dim.  As well, the line across his throat out along his arm is similar in shape to the line across the tip of his club and along the top of his head.  Use the Crown's curve to get oriented. Note that there is a small 'extra' star on the corner of Hercules' rectangular head opposite the Crown.

Lead across Hercules toward the eastern horizon and find the sky's fifth-brightest star, Vega in the Lyre.  Interestingly, the Earth's toy-top wobble that causes the Sun to drift through the seasons, also makes Earth's pole wander among the stars on a vast, slow circle.  In a mere 12,000 years, Vega will be the pole star.

Mythology
The myths of Hercules are the best-known Greek myths in Western culture, having formed the basis for a number of movies and TV shows.  Hercules was the son of the god Zeus and a mortal woman, which really annoyed Hera, wife of Zeus.  She delayed Hercules' birth and then put snakes in his cradle.  She later drove him mad so he would kill his wife and children.  When he went to the Delphic oracle for guidance, Hera made the oracle tell him to do 12 labours, which she thought would be impossible. The labours involve at least five constellations:

  • Leo represents the Nemean Lion, which Hercules killed with its own claw.  Ever after, he wore its skin for protection (but this is not the inspiration for Michael Ondaatje's In the Skin of a Lion)
  • Taurus represents the Cretan Bull
  • Hydra, the many-headed snake, was defeated by Hercules, in spite of Hera sending the Crab, Cancer, to nip his toes
  • Draco is the dragon he had to kill before getting the golden apples
Corona Borealis represents the crown of Princess Ariadne, daughter of King Minos of Crete.  She fell in love with Theseus, the Athenian hero whom she helped to defeat the minotaur.  She left Crete w/ him and his Athenian pals but he dumped her on an island.  Bacchus came to comfort her, and tossed her crown up amongst the stars.

The Lyre is, of course, the lyre of Orpheus, son of sun-god Apollo and the muse Calliope.  Orpheus played so well that the trees and rocks would weep.  When his wife, Eurydice, died and travelled to the underworld, Orpheus went there and charmed Pluto and Persephone with his music, so that they agreed to let her go back to her life on Earth.  There was a condition, though (there always is): he was not to look back at her until they reached the surface.  Well, he did, so she had to go back down.  He came to a gory end some years later when the Thracian women, whom he avoided after his wife's death, tore him apart.  On the bright side, he then got to go to the underworld and be with Eurydice, and Zeus tossed his lyre into the stars.

Interesting Objects

  • Globular cluster M13 (marked with a tiny triangle on the side of Hercules' head opposite the small 'extra' star) is easily seen in binoculars, and is a perennial favourite in a telescope.  Globular clusters are balls of thousands or even millions of stars orbiting the Milky Way galaxy.  The stars are mostly old, and there is very little gas or dust to make new stars.  Until recently they posed a real problem for cosmologists: they seemed to be older than the Universe.  A planet in M13 would never experience real darkness - even at night the entire sky would be illuminated by so many stars it would be as bright as a full moon is for us.

  • "If a model of M13 were constructed using grains of sand to represent its million stars with an overall diameter of three hundred miles, then the average distance between the grains would be three miles! Even at the centre the grains would be nearly a mile apart." (Brent Watson "Finder Charts for Bright Telescopic Objects" (c) 1995)
  • The Ring nebula is marked with a tiny triangle between the two stars marking where the Lyre's two strings meet the body of the Lyre, opposite Vega.  It is a planetary nebula, a spherical shell of gas and dust thrown off by a star in its death throes.