Welcome to the July night sky. The warm nights of this month offer the ideal conditions for all-night stargazing.
If you look towards the south in the early evening, we have the milky way constellations of Scorpius and Sagittarius visible, and looking overhead we can see the summer constellations of Cygnus, Aquila and Lyra. The brightest stars of these three constellations form a recognisable shape called the ‘summer triangle’.
The apex of this triangle points downwards towards the south during the long summer nights and the stars involved are Altair at the lower tip, and Deneb and Vega at the top.
Although these three stars appear to be visually of similar brightness, they are quite different. For example, Vega is a bright but very young star at less than 10% the age of our Sun. Altair is one of the closest stars to our solar system at approximately 16 light years’ distance. And Deneb is one of the brightest stars in our galaxy at approximately 10,000 times brighter than Altair but it appears to be a similar brightness because it is 100 times further away.
Close to the ‘summer triangle’ there is an area in the sky that the Kepler Space Telescope is looking at. This small area is being studied to reveal the presence of extra-solar planets, and more than 2,000 exoplanets to date have been confirmed and thousands of others are awaiting confirmation.
The mission has officially ended but is now being extended for a further two years. Undoubtedly many hundreds more exoplanets will be discovered. The purpose of the Kepler’s Telescope mission is to discover just how common planets are in our galaxy, as up until now there was no definite evidence of the quantity that existed. It now turns out that planets are common and most stars have their own “solar systems”. This practically guarantees the existence of many Earth-like worlds in our galaxy.
The last week of July has the Capricornid meteor shower visible. Traditionally, this shower has a number of bright meteors visible and the Moon will at last quarter this time so we should still have a dark sky.
The gas giant planet Jupiter sets in the west in the early evening this month, leaving still visible in the southern sky, close to the constellation of Scorpius, the red planet Mars and the ringed planet Saturn.
The moon is new on the fourth, first quarter on the 12th, full on the 19th and last quarter on July 27.
By Clive Jackson
Clive Jackson is the Director of the Camera Obscura (next to the Castle in Tavira), specialising in education and public outreach.
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To see the July Sky Map click on the pdf link below