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THE NIGHT SKY FOR NOVEMBER 2017

Northern Hemisphere

Ian Morison tells us what we can see in the Northern Hemisphere night sky during November 2017.

The Planets

  • Jupiter

    Jupiter passed behind the Sun on October 26th and so will become visible again in the pre-dawn sky after the first week or so November. It will then lie down to the lower left of Venus. However, by the end of November it will rise some two hours before the Sun allowing its 31 arcsecond disk, shining at a magnitude of -1.7, to be observed under clear skies. The low elevation will, of course, hinder our view.

  • Saturn

    Saturn can be seen low in the southwest during twilight this month dropping down towards the horizon a little more each week. Shining at magnitude +0.5, it sets around 2 hours after the Sun on the 1st but little more than one hour by month end. It starts the month moving slowly eastwards in Ophiuchus but reaches the boundary of Sagittarius on the 18th. Last month, Saturn's rings reached their maximum tilt to the line of sight of 27 degrees and it is a real pity that Saturn is so low in the sky. Sadly, this will not improve for quite a few years as Saturn moves slowly through the lowest part of the ecliptic. Towards the end of the month Saturn edges closer to Mercury, but with both so low above the horizon after sunset, will be difficult to spot.

  • Mercury

    Mercury passed between us and the Sun (Superior conjunction) on October 8th and will become visible again after sunset in the latter part of the month. From around the 17th, it might be glimpsed with binoculars low in the southwest 20 minutes after sunset shining at magnitude -0.4. It reaches greatest elongation, 22 degrees east of the Sun on November 23rd but, due to the shallow angle of the ecliptic to the horizon, never lies far above the horizon. In the last few days of the month its magnitude falls to -0.2 and it only lies ~5 degrees above the horizon 30 minutes after sunset.

  • Mars

    Mars, lying in Virgo, has now become a morning object at the start of its new apparition and rises three to four hours earlier than the Sun. During the month, Mars has a magnitude of 1.7 and an angular size of just 3.9 (increasing to 4.2) arc seconds so no details will be seen on its salmon-pink surface. On the 4th, Mars is just three degrees to the upper right of Porrima, Gamma Virginis. This closes to two degrees by the 6th whilst, at the end of the month, it will lie just 3 degrees to the upper left of Spica, Alpha Virginis.

  • Venus

    Venus, now moving back towards the Sun, rises some 90 minutes before dawn at the start of the month but this falls to 45 minutes by month's end. Its magnitude remains at -3.9 during the month as its angular diameter shrinks from 10.4 to 10 arc seconds. However, at the same time, its illuminated phase increases from 96% to 99% - which explains why its magnitude does not change. At the beginning of the month, it lies close to Spica, Alpha Virginis, with Venus some 100 times (5 magnitudes) brighter than Spica. By month's end, binoculars might be needed to spot it low above the eastern horizon. But please do not use them after the Sun has risen.

    HIGHLIGHTS

  • November - a good month to observe Neptune and Uranus with a small telescope.

    Neptune came into opposition - when it is nearest the Earth - on the 2nd of September, so will be well placed to spot this month. 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 charts. 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. Uranus reached opposition on October 19th and so is visible all night. It will be highest in the sky in the south around 1 am BST shining at magnitude 5.7 and with a disk 3.7 arc seconds across. It lies in Pisces, one degree and 18 arc minutes up to the right of Omicron Pisces as shown in the accompanying chart. Its turquoise green colour should be seen in a small telescope and it will be easily spotted in binoculars.

  • Around the 18th of November (with no Moon in the sky): find M31 - The Andromeda Galaxy - and perhaps M33 in Triangulum

    In the evening, the galaxy M31 in Andromeda is visible in the south. The chart provides two ways of finding it:

    1. Find the square of Pegasus. Start at the top left star of the square - Alpha Andromedae - and move two stars to the left and up a bit. Then turn 90 degrees to the right, move up to one reasonably bright star and continue a similar distance in the same direction. You should easily spot M31 with binoculars and, if there is a dark sky, you can even see it with your unaided eye. The photons that are falling on your retina left Andromeda well over two million years ago!
    2. You can also find M31 by following the "arrow" made by the three rightmost bright stars of Cassiopeia down to the lower right as shown on the chart.

    Around new Moon (18th November) - and away from towns and cities - you may also be able to spot M33, the third largest galaxy after M31 and our own galaxy in our Local Group of galaxies. It is a face on spiral and its surface brightness is pretty low so a dark, transparent sky will be needed to spot it using binoculars (8x40 or, preferably, 10x50). Follow the two stars back from M31 and continue in the same direction sweeping slowly as you go. It looks like a piece of tissue paper stuck on the sky just a bit brighter than the sky background. Good Hunting.

  • November early mornings: November Meteors.

    In the hours before dawn, November gives us a chance to observe meteors from two showers. The first that it is thought might produce some bright events is the Northern Taurids shower which has a broad peak of around 10 days but normally gives relatively few meteors per hour. The peak is around the 10th of November but then the Moon is close to third quarter so its light will intrude. The meteors arise from comet 2P/Encke. Its tail is especially rich in large particles and, this year, we may pass through a relatively rich band so it is possible that a number of fireballs might be observed!

    The better known November shower is the Leonids which peak on the night of the 17th/18th of the month. Happily, the Moon is new so will not hinder our view. As one might expect, the shower's radiant lies within the sickle of Leo and meteors could be spotted from the 15th to the 20th of the month. The Leonids enter the atmosphere at ~71 km/sec and this makes them somewhat challenging to photograph but it is worth trying as one might just capture a bright fireball. Up to 15 meteors an hour could be observed if near the zenith. The Leonids are famous because every 33 years a meteor storm might be observed when the parent comet, 55P/Temple-Tuttle passes close to the Sun. In 1999, 3,000 meteors were observed per hour but we are now halfway between these impressive events hence with a far lower expected rate.

  • November late night: Comet 2107 O1 (ASASSN).

    Throughout November, with binoculars or a small telescope, it should be possible to spot Comet 2107 O1 (ASASSN) as it nears the Pole Star. It was discovered in July by the 'All Sky Automated Survey for Supernovae' and brightened rapidly. Its brightness is now falling but, at magnitude +8 or +9, should be visible near the Pole Star this month.

  • November 6th - very early morning: The Moon occults Aldebaran and the Hyades Cluster

    In the early hours of the 6th November, a near full Moon, passing across the Hyades Cluster (at a distance of 153 light years) will occult the red giant star Aldebaran which lies at a distance of 65 light years in front of the Hyades Cluster.

  • November 15th - 1 hour before dawn: Mars and a crescent Moon

    In the hour or so before dawn, Mars will be seen to the right of a thin Crescent Moon.

  • November 16th - before dawn: three planets and a crescent Moon

    Just before dawn, Mars, a very thin Crescent Moon, Jupiter and Venus will form a lineup along the ecliptic. In the dawn glare, binoculars and a very low eastern horizon will be needed to spot them all but please do not use the binoculars after the Sun has risen.

    Claire Bretherton from the Carter Observatory in New Zealand speaks about the Southern Hemisphere night sky during November 2017.

    Kia ora and welcome to the November Jodcast from Space Place at Carter Observatory in Wellington, New Zealand.

    The Planets

      Mercury now joins Saturn in our western evening skies. Unfortunately it won't be as easy to spot as its last evening appearance in July-August, as it sets before twilight ends. At the start of the month orange Antares, the brightest star in Scorpius or Te Matau a Maui, will sit between the two planets, but as the stars and Saturn slowly sink closer to the horizon from night to night Mercury climbs higher, sitting level with Antares on the 14th and with Saturn on the 24th, when it also reaches its greatest elongation east.

    Constellations

      Scorpius/Te Matau a Maui has been dominating our evening skies over the winter months, but is now disappearing from view, ready to reappear in the morning over the coming months. As Scorpius sets in the west, his arch enemy, and our summer constellation, Orion rises towards the east along with Taurus and Canis Major. Antares, which marks the heart of the Scorpion, is also known as Rehua to Maori. It represents one of the four Pou, or pillars, that hold Ranginui, the sky father up in the sky. It sits just above the south western horizon at around 11pm at the beginning of the month. These four pou form the basis of a celestial compass, a map of the night sky that was used to navigate the vast pacific oceans and bring our Polynesian ancestors to Aotearoa/New Zealand.

      The other three pou are marked by Matariki (the Pleiades), Tautoru (the belt of Orion) and Takurua (Sirius), which line up along the eastern horizon. Matariki supports one of Rangi's shoulders and marks the rising point of the Sun at the winter solstice. Takurua (Sirius) supports the other shoulder and is the closest bright star to the Sun's rising point at the summer solstice. These two stars represent the extent of the Sun's movement throughout the year. In between, rising directly east, is Tautoru, or the belt of Orion, marking the rising point of the Sun at the time of the equinox.

      Stretching from Scorpius around to Orion is Te Waka o Tamareriti, or Tamarereti's canoe, which lines up along the southern horizon in our evening sky. The front of the canoe is marked by the tail of Scorpius, with the sting representing the beautifully carved wood that adorns the prow. The star at the end of the Scorpion's curving tail marks the place where the bow meets the water, whilst Rehua or Antares, marks the crest of a wave as the great waka glides through the waters of the Milky Way.

      The Southern cross marks the anchor, Te Punga and the pointers Alpha and Beta Centauri are the anchor line, Te Taura.

      Orion marks the stern of the canoe, with the elaborately carved stern post rising all the way up from red Betelgeuse to bluish Rigel. A tall mast rises from the waka all the way to Achernar, high in the south, the brightest star in the southern constellation of Eridanus, the river, which we explored last month. A little below Achernar, the two small fuzzy patches of light that make up the Large and Small Magellanic Clouds mark the waka\92s sails.

    • Mythology

      One story tells of Tamarereti sailing across the sky in his waka with all the stars in kete or baskets. He places the key seasonal and navigational stars in their correct positions in the sky, but he finds he has lots of smaller stars left over. So he capsizes his waka spilling all the smaller stars into the sky forming Te Ika Roa, or the Milky Way. Another story tells of Tamareriti scattering bright pebbles in the dark, lightless sky to help guide his way home. The pebbles became the stars and the wake of his waka formed the Milky Way. The sky we see in the mid-evening in October/November each year is, in fact, the same sky we see just before sunrise around June, the time we celebrate Matariki, or Maori New Year. It is said that the bright star Canopus, or Atutahi (the ariki or high chief of the heavens), pulls up the anchor at the start of the year starting the waka in motion. During the year you can track the progress of Tamarereti's waka as it moves across the sky, one day at a time.

    • Pegasus

      On the opposite side of the sky is the Great Square of Pegasus, the flying horse, leaping over the northern horizon. Last month we talked a little about this wonderful constellation, its brightest star Enif, marking the horse's muzzle, and the beautiful globular cluster, M15. But we can also use Pegasus to help us find some of our nearest galactic neighbours.

    • Alpheratz and M31

      The star at the bottom right of the Great Square of Pegasus is in fact Alpha Andromodae, or Alpheratz, the brightest star in the constellation of Andromeda. Located some 97 light years from Earth it is a spectroscopic binary star whose two components orbit each other in just 100 days. M31 is approaching the Milky Way at 110 km/s and is expected to collide and merge with our own Galaxy in around 4 billion years.

    • M33

      A little higher and towards the east, the Triangulum galaxy or M33 is better placed in our skies. At around 3 million light years from Earth and shining at magnitude 5.7 it is just at the limit of naked eye visibility under excellent conditions, making it one of the most distant objects able to be glimpsed unaided. To find M33, head back from Andromeda towards Mirach and then continue a similar distance to the other side. Whilst spotting it with the naked eye is a real challenge, it is easily observable in a pair of binoculars. With the mass of 10s of billions of Suns, M33 is also approaching us, at around 100,000 kilometres per hour. The most striking feature of the Triangulum Galaxy is a massive region of star formation, known as NGC604, which can be seen with a small telescope. NGC604 is 100 times larger than the Orion Nebula and contains over 200 hot, massive blue stars formed just 3 million years ago. In fact, if it were at the same distance as the Orion Nebula, it would be second brightest to only the Moon in the night time sky.

    • Leonids Meteor Shower

      Look out for the Leonid meteor shower, which peaks around the 17th -18thof the month, when the Earth passes through the trail of dust and debris left behind by the comet Temple-Tuttle. Whilst normally a reliable but fairly quiet meteor shower, observers have noticed that roughly every 33 years the number of meteors observed during the shower shows a marked increase as the Earth passes through the denser parts of the cometary debris trail. The radiant of the shower, from which the meteors appear to originate, is located in the constellation of Leo, which rises only a couple of hours before the Sun in our morning sky. The best time to observe the Leonids is about 2-3 hours before sunrise on the mornings around the peak. Look around 20 degrees away from the radiant point for the best chance of meteor spotting.

    Wishing you clear skies from the team here at Space Place at Carter Observatory.

    Compiled by Ian Morison


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