Friday, 2 December 2016

THE DECEMBER SKY AT NIGHT

Dec 2016

Northern observers have both their main 'guides' on view. Orion attains a respectable altitude by mid-evening, and Ursa Major is well above the north-east horizon, even though the Great Bear does appear to be standing on its tail. Capella in Auriga is very close to the overhead point, which means that Vega is skirting the northern horizon and we have certainly lost the Summer Triangle, though in fact Deneb, like Vega, never actually sets over the British Isles. Cassiopeia is high in the north-west.

Pegasus remains visible in the west, though before very long it will start to merge into the evening twilight. Sirius has made its entry, and around midnight Leo appears over the eastern horizon. The Milky Way is at its best, running right across the sky from Cygnus through Cassiopeia, Perseus, Auriga and Gemini down to the horizon.

Southern observers lack Ursa Major, but Orion is excellently placed together with the Hunter's retinue; Achernar is close to the overhead point, and Canopus is also high and Pegasus well above the horizon. Capella is very low in the north, and the Southern Cross also is badly placed during December evenings. The Milky Way is superb, and so too are the Clouds of Magellan; it is sad that there are no comparable Clouds in the northern hemisphere of the sky.

moon

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Monday, 24 October 2016

The Night Sky: November 2016

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Northern hemisphere observers can once again use Orion, which rises in mid-evening though it is not at its very best until after midnight. Much of the Hunter's retinue is on view - Capella, Aldebaran, the Twins - though Sirius does not appear until later. Ursa Major is still low in the north, and Arcturus has disappeared; the W of Cassiopeia is almost at the zenith. We are losing the Summer Triang...le as a dominant feature, and Altair sets before midnight. Pegasus is still there, with Andromeda and Perseus; Cetus and Eridanus sprawl across the southern aspect, but we have to ail intents and purposes lost Fomalhaut in the evening twilight. This is a good time of the year to track the Milky Way, from Cygnus right across the zenith and down to Gemini in the east.

My new program: 'The Clouds of Magellan' will be available to watch soon :)

From southern countries, this is an ideal time to study the Clouds of Magellan, which, with the Southern Birds, are almost overhead. Orion is with us once more, and Sirius shines brilliantly in the east; Canopus is high up, and it is interesting to compare the two. Sirius looks much the brighter, and one has to use one's imagination to realize that compared with Canopus it is puny; according to the figures in the Cambridge catalogue, it would take more than 7500 stars of the luminosity of Sirius to equal the power of Canopus. Achernar is high, and the Cross still rather low in the south. The Square of Pegasus is setting in the north-east, but Andromeda remains visible low over the horizon. Cetus is well displayed, and we can see the whole of the River Eridanus, from the area of Orion through to the far south.

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Friday, 26 August 2016

The Autumn Sky | Northern hemisphere

0h 15 Sept

With the autumn equinox on 22 September the nights are now getting longer, and the autumn constellations are coming into view. Andromeda the chained maiden, Pegasus, the winged horse and Perseus the hero are all there, and so are Andromeda’s parents Cassiopeia, the queen, and Cepheus the King, all of which represent the famous legend of the stars.

According to the Greek legend, Andromeda was the beautiful daughter of Cepheus the King of Ethiopia. Her mother, Queen Cassiopeia, enraged the sea nymphs by boasting of her beauty. Neptune, in order to punish her for vanity and conceit that her cherished daughter should be chained to a rock by the seashore, where she would become pray of a terrible sea monster that was ravaging the coast.

The unfortunate Andromeda was forced to submit to this barbarous treatment, and in chains awaited her fate. Luckily, just as the monster Arrived on time, just as the monster was about to seize her, Perseus the champion flew down to her rescue bearing with him the hideous head of the Medusa. He held this up before the monster’s eyes and straight away the creature was turned into stone, and Perseus gallantly released Andromeda, and as a just reward he married her.

Low in the northern sky the seven bright stars marking the plough are low down, the two forward stars of the bowl, Marek and Dubhe, are known as the pointers because they lead the way to Polaris the Pole star which is high up. Continue the imaginary line further and you arrive at the doll’s house pattern of stars marking Cepheus with constellation of Cassiopeia close by. The five bright stars are a prominent so cannot be mistaken.

Cassiopeia lies in the Milky Way so this area of sky is rich in open star clusters all visible in a pair of 10x50 binoculars. Two of the stars point down into the NE along the Milky Way into the nearby constellation of Perseus. Midway between the two constellations is the lovely double star cluster NGC 869 which is wonderful to see in binoculars. A little further down is the relatively bright star Beta Persei, otherwise known as Algol, which represents the eye of the Gorgon, Medusa. It is a variable star that is usually of magnitude 2.3, but regularly at intervals of 2 days and 20 hours its brightness decreases. In 4½ hours in wanes to Mag 3.5, then after 20 minutes it brightens again to Mag 2.3.

Returning to the stars of Cassiopeia the opposite two stars lead the way onto the SSE where the constellation of Andromeda is on view high up. The 4 bright stars of Andromeda form a line a short distance across the sky originating in one corner of the great square of Pegasus. That star is named Alpheratz, next in line is Beta Andromedae, followed by Beta (Mirach), and finally Gamma (Alamak) which is a lovely double star; through a small telescope the two stars have a contrast of yellow & blue. The most celebrated object in constellation is the great Andromeda Galaxy M31, which can be found at the top of a line of 2 stars above Mirach the mid star of the figure.

The Andromeda galaxy is visible to the unaided-eye on crisp clear evenings, binoculars show it really well. M31 lies at a distance of 2.2 million light years and is a true spiral galaxy like our own Milky Way Galaxy. Its splendid appearance is clearly shown in deep sky photographs that can be captured by amateur astronomers with the right equipment; this image was taken by my friend Terry Hancock.

Another reasonably bright galaxy M33 lies directly below Mirach in the constellation of Triangulum.

The constellation low down in the SE is Cetus that represents the celestial monster in the Perseus & Andromeda legend.

Reasonably high up in the western sky are the 3 bright stars that make up the Summer triangle, Deneb in Cygnus the celestial swan, Vega in Lyrae, and Aquila the Eagle. Cygnus lies in the rich star field of the Milky Way and so binoculars will reveal a number of star clusters and nebula, which are colourful gas clouds in space.

Vega (α Lyrae) is a bright blue star, and close by is the lovely double star epsilon Lyrae, which is a multiple star system also visible with binoculars.

So there is much to see in the autumn sky, and a pair of binoculars is all you will need to see many of the lovely star clusters, nebulae and galaxies on show.

The Autumn Sky | Southern hemisphere

0h 15 Sept SH

Earth size planet discovered orbiting our nearest star