EYES ON THE NIGHT SKY: AUGUST 2018
Welcome to Eyes on the Night Sky for August. This month is known as the start of the astronomy season as night falls at an earlier time and we can begin to enjoy studying galaxies and nebulae at their best. The Milky Way, part of the galaxy we live in, is visible at an earlier time this month. If the light pollution in your area isn't much of a problem, the Milky Way can be seen from your own home. Take a look at the light pollution map here – if you live in the green zone, you may see the Milky Way arching right over your head (at the Zenith). In light pollution-free areas such as the Elan Valley Dark Sky Park, rifts and bright, dusty lanes can be spotted stretching across the sky and will be truly jaw-dropping. As you look south towards the horizon, where the constellation of Sagittarius is situated, you are actually gazing into the centre of our Galaxy!
As we are looking southwards, grab some binoculars and study the Wild Duck Cluster (M11) in the constellation of Scutum. It was first discovered in 1681 and is known to contain nearly 3,000 young, hot stars. Through binoculars, this open cluster resembles a globular cluster due to the close nature of its many stars and looks like a flock of flying ducks. The Wild Duck Cluster is around 5,500 light years away. To find it, look for the star Altair in Aquila and its two neighbouring stars, Tarazed and Alshain. Follow the central spine of this constellation in a 5 o'clock position until you get to the tail. M11 lies between the tail and the top part of the Scutum constellation. If you have a telescope, you will be able to see this cluster in more detail.
Whilst in the area, we will study the Omega Nebula (M17) in the constellation of Sagittarius. This target is just about visible with the unaided eyes in a very dark, moonless sky. Look for the teapot asterism that forms part of the Sagittarius constellation and the Omega Nebula sits in a 1 o’clock position above the ‘lid’ (a star called Kaus Borelalis). This nebula is a massive nursery, giving birth to hot stars and from our perspective, is seen edge on. Its precise distance isn’t known but may be up to 6000 light years away. Through binoculars it appears as an oval shape but through telescopes of 4 inches of aperture and larger, the nebula starts to resemble a graceful swan. It is also known as the Swan Nebula for that very reason. The official designation is M17 or NGC6618.
A third target for this month is the Ring Nebula (M57), further up in the sky, at the feet of the constellation Lyra. Look for the bright star Vega, which forms part of the Summer Triangle and just below it at the 8 o’clock position, look for a four star parallelogram. At the base of this shape, in between the two stars Sulafat and Sheliak, lies this curious planetary nebula. It’s quite a tricky nebula to find but well worth the effort. Resembling a ring, this nebula is the remains of a sun-like star and lies 2000 light years away. You won’t be able to see this through binoculars due to its small size but you will be able to see the ring structure in an 8 inch telescope. A filmy texture can be seen through larger telescopes of 14 inches and above and the central star has been spotted through 16” telescopes on exceptionally dark nights.
The highlight of this month is the best meteor shower of the year: the Perseids. The New Moon on will not hamper visibility during the peak of this shower, which falls between the nights of 11th and 13th August, which means we could be in for a treat. This year, it is thought that we may see between 60 and 70 meteors per hour. To view them at their best, go out into the countryside, away from light pollution and get comfortable for a few hours after midnight. The Perseids are caused by the Earth passing through the orbit of the comet Swift-Tuttle which has left debris in its wake.
We hope you enjoyed the partial lunar eclipse last month. This month, you may be able to catch some earthshine during the Moon’s waxing crescent moon from 12th to 17th August and during the waning crescent phase around 5th to 10th August. The New Moon falls on 11th August and the Full Moon on 26th August.
See you next month for some more amazing night sky targets.