The Night Sky
Ian Morison tells us what we can see in the northern hemisphere night sky during August 2017.
Highlights of the Month
August - Find the globular cluster in Hercules and spot the 'Double-double' in Lyra. Just to the left of the bright star Vega in Lyra is the multiple star system Epsilon Lyrae, often called the double-double. With binoculars a binary star is seen but, when observed with a telescope, each of these two stars is revealed to be a double star - hence the name!
August - A good month to observe Neptune with a small telescope. Neptune comes into opposition - when it is nearest the Earth - on the 2nd of September, so will be well placed both this month and next. Its magnitude is +7.9 so Neptune, with a disk just 3.7 arc seconds across, is easily spotted in binoculars lying in the constellation Aquarius as shown on the chart. It rises to an elevation of ~27 degrees when due south. Given a telescope of 8 inches or greater aperture and a dark transparent night it should even be possible to spot its moon Triton. (This is my objective around the end of the month!)
The Moon and Saturn - Late evening on the 2nd of August, the waxing Moon will be seen to the upper right of Saturn. Antares lies down to its lower right.
The mornings of August 12th and 13th: midnight to dawn - look out for the Perseid meteor shower. If clear, these mornings should give us a chance of observing the Perseid meteor shower - produced by debris from the comet Swift-Tuttle. The early morning of the 12th August will give us the best chance, if clear, of viewing the shower, but the peak is quite broad and so it is well worth observing on the nights before and after. Most meteors are seen looking about 50 degrees from the 'radiant' which lies between Perseus and Cassiopeia. This year a gibbous Moon rises before midnight so will be low in the sky for some time the early hours of the 12th so it will be best to observe them as soon as it is really dark. Moonlight will hinder our view, but it should still be possible to spot many meteors. NB: As we need to view a very wide area of sky, normal binoculars would be of no use, but the Vixen SG 2.1 x 42 that I have just reviewed in the Astronomy Digest, could be useful as they will darken skylight from the Moon somewhat and enable fainter meteors to be seen - albeit over a smaller field of view.
16th August 07:40 - 08:40 BST: A daylight Occultation of Aldebaran - In the early morning of the 16th, Aldebaran will be occulted by the Moon - visible with a telescope (but keep it well away from the Sun). The times are for London and will vary somewhat across the country. In a line from Leverburgh on the Isle of Harris across to Wick, a grazing occultation will be seen at 8:01 BST.
19th August - before dawn: Venus and a thin crescent Moon - Before dawn on the 19th, if clear, Venus will be seen just 2 degrees above a very thin waning crescent Moon.
25th August - after sunset: Jupiter below a thin crescent Moon - After sunset on the 25th, if clear, Venus will be seen below a thin waxing crescent Moon.
August 14th and 30th: The Straight Wall - The Straight Wall, or Rupes Recta, is best observed either 1 or 2 days after First Quarter (30th August: evening best) or a day or so before Third Quarter (evening of the 14th August best). To honest, it is not really a wall but a gentle scarp - as Sir Patrick has said "neither is it a wall nor is it straight"!
Claire Bretherton tells us what we can see in the southern hemisphere night sky during August 2017.
Kia ora and welcome to the August Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.
Last month we looked at some of the amazing objects in Scorpius and Sagittarius, towards the centre of the Milky Way. This month we'll move along a little from our Galaxy's bright centre to where it passes overhead through Centaurus, Crux, the Southern Cross, and the constellations of Carina, Vela and Puppis that make up the great ship Argo Navis.
Crux - Crux, the Southern Cross lies on its side after sunset in the south western sky, with the Diamond Cross and false cross below. Above Crux are Alpha and Beta Centauri, the brightest stars in the constellation of Centaurus. Known as the pointers, they guide our eye to Gamma Crucis, the star at the top of Crux, and help us identify the true Southern Cross.
Omega Centauri - To the right of the pointers, and just outside the main band of the Milky Way is the spectacular globular cluster Omega Centauri. This is by far the largest and brightest globular cluster in the Milky Way appearing as a fuzzy star to the naked eye. With binoculars it is an even more stunning sight, spanning almost a full degree of the sky, twice that of the full moon, whilst a small telescope will show a shimmering ball of stars, with many individual stars visible towards the outskirts.
The Jewel Box - Close to Beta Crucis, in the Southern Cross, is a different type of star cluster. NGC 4755, also known the "Jewel Box", is an open cluster about 6,500 light years away. It is rich and bright with the stars showing an array of different colours, highlighted by an orange-red supergiant. At magnitude 4.2, the Jewel Box can easily be seen with the naked eye. It is dominated by an A-shaped asterism of bright stars, which is observable with binoculars, whilst even a small telescope will reveal a stunning sight. The name comes from Sir John Herschel's vivid description of the cluster as a "casket of variously coloured precious stones".
Coal Sack - Just to the left is a dark patch known as the Coal Sack nebula. This is a huge cloud of interstellar dust and gas some 700 light years away. It is so thick and dense that it obscures the light from more distant stars, appearing as a darkened area against the bright backdrop of the Milky Way. Aboriginal astronomers have observed the Coalsack for at least 40,000 years, whilst to Māori here in New Zealand it is known as te Patiki or the flounder.
Carinae Cluster - Below the Coalsack, at the tip of the Diamond Cross asterism in Carina is the Theta Carinae cluster, or IC 2602, an open cluster containing around 60 individual stars. At magnitude 1.9 it is the third brightest open cluster in the sky and is often known as the Southern Pleiades, although it is still much fainter than its northern counterpart. The cluster spans around 50 arcminutes, over 1.5 full moon diameters, so it is best viewed with binoculars or a low powered telescope giving a wide field of view.
Carinae Nebula - Around 4 degrees to the right of Theta Carinae is the famous NGC 3372, the Eta Carina nebula, a huge cloud of glowing gas estimated to be around 7500 ly away. At 4 times the size of the Orion Nebula, it is one of the largest nebulae of its type in our skies. With the naked eye you'll be able to pick out the brightest central areas, but with binoculars you should be able to see Eta Carinae itself as a golden star within the nebula. Eta Carinae is actually a system of at least two stars, which combined are around 5 million times more luminous than our Sun. The largest has around 90 times the Sun's mass and is so bright that the radiation pressure it produces is almost too strong for the gravity holding it together, causing a constant stream of material out into space.
Highlights of the Month
Venus - In the morning skies, Venus is now rising around 5am. The Moon will pass nearby on the 19th, sitting just above Venus in the north east at sunrise. The two will move towards the north by midmorning, providing a perfect opportunity to try and spot Venus in the daylight, with Venus sat just to the right of a thin waning crescent Moon.
Wishing you clear skies from the team here at Space Place at Carter Observatory.
Provided courtesy of: http://www.jodcast.net/