The Night Sky in November, 2017

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1 The Night Sky in November, 2017 Several people contacted me in October to thank me for explaining the Harvest Moon, Hunter s Moon and a Blue Moon. If any of you have any questions you would like to ask then please contact me. I will be able to include replies to these in this Newsletter. Two interesting events occurred in October and I would like to start by mentioning these. The first was the very red Sun which was visible on October 17 th. This was caused by dust from the Sahara brought in by Hurricane Ophelia. It made the sun look like the science fiction images of Mars! Below is an image taken by a fellow astronomer Julian Mole. For the keen photographers among you, Julian took this with a Canon 7D Mk II camera mounted on a tripod. The camera settings were 1/800 sec, ISO 400 and f/9. He used a 400mm lens with a 1.4 teleconverter which is a lens inserted between the camera body and the main lens as shown in the second image below. It enlarges the central part of the image. The other interesting event is that gravitational waves have been detected again. These were caused by the collision of two neutron stars which occurred 130 million years ago! The waves have only just reached us! If the you haven t seen the video of this then click on the link million-years-ago. As the neutron stars spiralled together, they emitted gravitational waves that were detectable for about 100 seconds; when they collided, a flash of light was emitted and seen on Earth about 2 seconds after the gravitational waves. The waves were detected by the two LIGO detectors in the USA and the VIRGO detector in Italy. Neutron stars are the smallest, densest stars known to exist and are formed when a massive star explodes in a supernova. The stars consist only of neutrons one of the particles that forms the nucleus of an atom. The star is so dense that a teaspoonful of matter from it would weigh billions of tons! Some neutron stars spin very rapidly and emit radio waves in the form of a pulse rather like the beam of light from a light house as shown in the image below. They are known as pulsars and were discovered by a British astronomer, Dame Jocelyn Bell Burnell working on a radio telescope in Cambridge.

2 Now to the night sky in November. There will be a Full Moon on November 4 th and a New Moon on November 25 th so the middle and end of the month will be the best for stargazing. This is also good for the Leonid meteor shower which will be visible from November 6 th until the 30 th but and will peak at 16:30 on November 17 th. The best time to see them will be after midnight on the 18 th. The radiant for this shower is in the constellation of Leo the Lion in the sickle which forms the head of the lion as seen in the image below. Note that the Big Dipper is the American name for the Plough. The star chart below shows the sky in the east over Oxfordshire at 2am on November 18 th. You can see that Leo has just risen. The Leonids are caused by the Earth passing through the debris left by the comet Temple-Tuttle which takes 33 years to orbit the Sun once. The shower is famous since it can sometimes produce a storm of thousands of meteors per hour. This last happened in 1998 and won t happen again for about another 15 years. An hourly rate of approximately meteors is expected this year. If you don t want to be out in the cold in the early hours, then do not despair. You may be lucky and see a meteor at other times. If you happen to be awake around 7:30 am on November 18 th then look low in the southeast and you will be treated to the sight of Jupiter, Venus and Mars as shown in the star chart below.

3 However, November is not a good month for planets this year but it is a good time to do some deep sky observing. This you can do whether you only have a pair of 10x50 binoculars or whether you have 15x70 binoculars or a telescope. The region around the constellation of Cygnus the Swan is a good area for this. The star chart below shows the sky in the west at 21:00 on November 17 th. In the middle near the horizon you can see the constellation of Cygnus. The long neck of the swan is pointing down and the wings are shown each side. This constellation is sometimes known as the Northern Cross since it is like a large cross. Its brightest star is Deneb. Above this is the small constellation of Lacerta the Lizard which I have highlighted. To the left of it is Pegasus and to the right is Cepheus which looks like the gable end of a house. To the right of this is the pole star Polaris and Ursa Minor (the little bear). Below this is the meandering constellation of Draco the Dragon. Most of the stars in this are quite dim but the head of the dragon is a distinctive asterism and is known as the lozenge. The brightest star in the head is Eltanin. To the right of Cygnus near the horizon is the constellation of Lyra the Lyre with it very bright star Vega. To the left of Cygnus are the small constellations of Sagitta (the arrow), Delphinus (the dolphin), Equuleus (the little horse) and Vulpecula (the little fox). See if you can identify these constellations the larger ones with the naked eye and the smaller ones with binoculars.

4 You can see that there are 8 Messier objects in the star chart above, their names begin with M. Remember that a Messier object can be one of only 3 things. It can be a cluster of stars which are all born out of the same cloud of gas at the same time. These can be open clusters or globular clusters. A Messier object can also be a planetary nebula or a distant galaxy. The term planetary nebula means a cloud of gas and has nothing to do with planets. Here is my challenge for this month how many of these can you spot? Here they are listed: M15 (NGC 7078) is a globular cluster in Pegasus. It is very round and bright even though it is 30,600 light years away M71 (NGC 6838) is a globular cluster in Sagitta and is 13,000 light years away M27 (NGC 6853) is the Dumbbell Nebula in Vulpecula. It is a favourite target for imagers and is 815 light years away M29 (NGC 6913) is an open cluster in Cygnus and is 4,400 light years away M39 (NGC 7092) is an open cluster in Cygnus and is 950 light years away It is positioned about halfway between this constellation and Lacerta. M56 (NGC 6779) is a globular cluster in Lyra and is 31,000 light years away M57 (NGC 6720) is the famous Ring Nebula in Lyra It is another favourite with imagers and is 1,140 light years away M102 (NGC 5457) is also known as M101 since Messier famously made a mistake and put a duplicate of this in his catalogue. It is called the Spindle galaxy and is a face-on spiral galaxy which is 17.5 million light years away You will notice that all the Messier objects have NGC numbers which means they are in the New General Catalogue (see last month s newsletter). Last month I also mentioned IC objects in the Index Catalogue and C objects in the Caldwell catalogue. But there are more ways of labelling celestial objects! Many are in the HIP catalogue, M102 is also HIP HIP stands for the Hipparcos Catalogue which was compiled from the data gathered by the Hipparcos satellite launched by ESA, the European Space Agency. This satellite gathered high quality data between November 1989 and March It also produced the Tycho-2 Catalogue which documents 2.5 million stars with names beginning with TYC! Now to the Southern hemisphere!

5 What's Up in the Southern Hemisphere? From the beginning of the month onwards, you will have the pleasure of seeing the planet Mercury together with Saturn low on the southwestern horizon. The star chart below shows the sky over Sydney at 20:00 on November 18 th. There you can see Mercury close to the constellation of Scorpius and Saturn above it in Sagittarius. To the left of the chart you can see the Southern Cross and the two pointer stars to the right of it. You will also be able to see the Leonid meteor shower but the best time for you will be around 3 am. The star chart below shows the sky in the east over Sydney at 03:00 on November 18 th. There you can the constellation of Leo with the sickle representing the head of the lion. This is where the radiant will be the point from which the meteors appear to be coming. Notice also that Mars is visible close to the eastern horizon.

6 I can t set you the same challenge I set to the people in the northern hemisphere since Cygnus is way below your western horizon. However, the star chart below shows you what you will see over Sydney in the northwest at 21:00 on November 17 th. I have highlighted the little constellation of Lacerta the Lizard which is just about to set. In the northwest you can just see the star Gienah which is in one of the wings of Cygnus. To the left of this is Vulpecula and then Sagitta. Above this you can see Delphinus and Equuleus. In the top right is Pegasus. Here is my challenge for this month there are 8 Messier objects in the above chart. How many of these can you spot? Here they are listed: M15 (NGC 7078) is a globular cluster in Pegasus. It is very round and bright even though it is 30,600 light years away M71 (NGC 6838) is a globular cluster in Sagitta and is 13,000 light years away M27 (NGC 6853) is the Dumbbell Nebula in Vulpecula. It is a favourite target for imagers and is 815 light years away M72 (NGC 6981) is a globular cluster in Aquarius and is 56,400 light years away M73 (NGC 6994) was catalogued by Messier as an open cluster in Aquarius It is now known that these stars are not close together in space and it is now defined as an asterism. So, this is an unusual Messier object. M2 (NGC 7089) is a globular cluster in Aquarius and is 37,000 light years away M31 (NGC 224) is the Andromeda galaxy and is 2.3 million light years away M32 (NGC 221) is a dwarf elliptical galaxy at the same distance as M31 Well that is all until next month. Meanwhile happy stargazing! Dark skies! Valerie Calderbank FRAS