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The Sky at Night for August 2016

Events in DARK text happen during darkness. LIGHT text during daylight, i.e. we can't see them.

Note: Times are calculated for Liverpool and will vary slightly across the UK

Planet Date Rises ? Transits ? Sets ?
Planet Event ? Date Time Sun Angle ? Each month, we identify the best constellations to be seen from the UK between 9pm and 10pm.

This month we'll be looking for the summer constellations of Lyra, and Scutum,
which can be found towards the south in the August night sky.

Night Sky in August

Lyra - is named after the Latin word for 'Lyre', which is a type of harp that was used by the ancient Greeks. Whilst it is a relatively small constellation, being only 52nd largest of the 88 modern constellations, its main star, Vega, is the fifth brightest star in whole the night sky. This makes the locating of Lyra a fairly easy task, especially given its position within the Summer Triangle - see below. Vega has been extensively studied by astronomers, and was the first star, other than the Sun, to have its photograph taken and the first to have its spectrum photographed. Due to the precession of the Earth (its rotation axis changing direction - a bit like a spinning top), Vega was once the northern pole star at about 12,000 BC and will be so again around 14,000 AD. Lyra is a rapidly rotating star (once every 12.5 hours) that is just over twice the mass and radius of the Sun, and pumps out around 50 times as much energy. It is white-ish coloured star that appears bright to us because it is just 25.3 light years away.

Scutum - is named after the Latin word for 'shield' and is one of the few constellations that owes its name to a historical figure, rather than a mythological being of object. It was so named back in 1683 after the Polish King, John III Sobieski, following a famous victory at the battle of Vienna. It is a very small constellation, at just 84th largest of the 88 modern constellations, and contains no bright stars. This makes is somewhat difficult to identify, and requires knowledge of the Summer Triangle to start off from, followed by a good deal of patience. Scutum contains several open clusters, as well as a globular cluster and a planetary nebula. The most notable object in Scutum is M11, the Wild Duck Cluster, which is a dense open cluster containing around 2900 stars.

Summer Triangle - is not actually a constellation, but is three bright stars called Vega, Altair and Deneb, which make up a triangular shape during the summer months and can help us to identify less obvious constellations in the vicinity. Because the stars all look about the same brightness, it's easy to think that they are about the same distance away. However, Deneb is actually 100 times more distant than Altair, which is only 17 light years away. For Deneb to appear almost as bright as Altair in our sky means that Deneb must be far brighter than Altair in terms of true light output. In fact astronomers estimate that it pumps out around 60,000 times more light than our Sun, while Altair outshines the Sun by just 13 times. Vega, by comparison, is 25 light-years away and some 50 times brighter than the Sun. The reason Deneb is so bright is because it's a type of star known as blue supergiant, whose size is around 200 times larger than the Sun. Because supergiants are in the last stages of their lives, it's likely that Deneb will become a supernova in the next couple of million years - which could cause significant problems for us still stuck on Earth when it goes off.