Brian Jones: Virgo

STARS THAT HERALD THE HARVEST

Virgo is a long and sprawling constellation which can be found straddling the south-eastern horizon during mid-evening in April and May. The stars of Virgo form a conspicuous Y-shape and the brightest star in the constellation, Spica, is quite prominent. Denebola, the star marking the tail of the adjoining constellation Leo (see last month’s column) lies just to the north west of Virgo, as shown here.

According to the early Greeks Virgo symbolised a pure and unpolluted Earth, although other legends associate the constellation with Ceres, the goddess of the harvest. In these accounts Spica represents an ear of wheat held in Virgo’s left hand. Egyptian mythology states that the misty band of light that we see as the Milky Way was formed by Virgo throwing millions of wheat heads up into the sky. Finally, on a somewhat bizarre note, the Greek philosopher Pliny said that if ever a comet was seen in the constellation, then great misfortune would befall all females here on Earth.

Spica is a brilliant blue-white star shining from a distance of around 275 light years. Spica is actually the 16^th brightest star in the sky and has a true luminosity of well over 2,000 times that of our Sun. Found a little way to the northwest of Spica is Porrima which shines from a distance of around 32 light years, making it one of the closest stars in the sky. The Arabic name for this star was Zawiat al Awwa. According to the Persian astronomer Al Biruni, ‘Awwa’ meant ‘turn’, referring to this star’s position at a turn, or bend, in the line of stars which it certainly is.

A little fainter than Porrima is Zavijah, a yellow-white star located at the western end of Virgo. Minelauva is situated to the north east of Porrima and has been found to lie at a distance of around 180 light years and to have a true luminosity of around 85 times that of the Sun. The Babylonians referred to this star as Lu Lim, which means stag, gazelle or goat. Stranger, and less romantic than this, is the ancient Chinese name Tsze Seang – meaning ‘the Second Minister of State’!

The name given to the yellow star Vindemiatrix is derived from the Latin for grape gatherer, a name derived from the fact that the star was seen to rise just before the Sun at around the time of the annual harvest. When seen through binoculars, Vindemiatrix offers a nice colour contrast with the white star Heze. Both shine from a distance of around 90 light years.

As you check out Virgo, you will notice a bright star like object a little to the east of Porrima. This is the ringed planet Saturn which, throughout 2011, is located in the same area of sky as Virgo. Its apparent location within the constellation is purely a line-of-sight effect. The stars we see in the night sky, including those forming the constellation Virgo, all lie at tremendous distances from us, unlike Saturn which, as a member of the Solar System, is a relatively close celestial neighbour.

Although the ring system for which Saturn is famous is not visible without at least a small telescope, it is interesting to watch the position of the planet change from week to week as it travels along its orbit around the Sun. Throughout April and May it will be seen to slowly move towards Porrima. If you check out its position every few days or so you will notice the change of position of Saturn against the backdrop of stars. In early-June it will be quite close to Porrima, after which it will slowly move away to the east. By late August Virgo, and Saturn, will be setting during the early evening and will be lost in the twilight glare.

Now that the warmer evenings beckon, stargazing is even more enjoyable, so why not check out the sprawling but distinctive constellation Virgo? Happy stargazing!