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THE NIGHT SKY FOR JANUARY 2018

Northern Hemisphere

Ian Morison tells us what we can see in the northern hemisphere night sky during January 2018.

  • Jupiter. Jupiter is now a pre-dawn object rising some three and a half hours before the Sun at the beginning of the month with its 33 arc second disk, shining at a magnitude of -1.8, to be seen under clear skies. As the month progresses, its apparent diameter increases to 35.8 arc seconds and it brightens to magnitude -2. The elevation before dawn will then be sufficiently high to enable crisp views of the giant planet to be seen with the equatorial bands, sometimes the Great (but reducing in size) Red Spot and up to four of its Galilean moons visible in a small telescope.

  • Saturn. Saturn passed behind the Sun on December 21st (superior conjunction) on December 21st and reappears in the pre dawn sky this month at the start of its new apparition. It is unlikely to be seen in the first week of January, but climbs higher and so becomes easier to spot as the month progresses as its brightness increases to +0.6 magnitudes. The rings were at their widest a few months ago and are still well open.

  • Mercury. Mercury reaches greatest elongation west on New Year's Day shining at magnitude -0.3. It will be seen low in the Southeast before dawn and will be visible for a couple of weeks before sinking back towards the Sun. Its angular diameter reduces from 6.7 to 4.9 arc seconds but, as the percentage illuminated surface area increases from 62% to 95%, its brightness remains constant throughout the month.

  • Mars. At the start of the month Mars lies in Libra but moves down into Scorpius at the end of the Month. A morning object at the start of its new apparition, it rises four hours or so earlier than the Sun. During the month, Mars has a magnitude increasing from 1.5 to 1.2 and an angular size of just 4.8, increasing to 5.6, arc seconds so no details will be seen on its salmon-pink surface. Moving eastwards, Mars has a very close conjunction with Jupiter on the 6th of January.

  • Venus. Venus, passes through superior conjunction (on the far side of the Sun) on January 9th and so cannot be observed this month.

  • Highlights

  • Around the 17th of January (with no Moon in the sky): find M31 - The Andromeda Galaxy - and perhaps M33 in Triangulum Around new Moon (17th January) - 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).

  • January 5th before dawn: A waning Moon closes on Regulus in Leo. If clear before dawn on the 5th, a waning Moon between Full Moon and Last Quarter lies just a few degrees from Regulus in Leo.

  • January 6th before dawn: Mars and Jupiter up close. If clear before dawn on the 6th and looking to the South-Southeast, Mars, at magnitude 1.4 will be seen just to the right of Jupiter shining at magnitude -1.8. At their closest they will be just 23 arc seconds apart.

  • January 13th before dawn: Saturn and Mercury. Looking Southeast before dawn on the 13th and given a very low eastern horizon, one might be able to spot Saturn at the start of its new apparition lying just above Mercury. A very thin crescent Moon will be seen up to their right. Binoculars may well be needed but please do not use them after the Sun has risen.

  • January 26th: Two Great Lunar Craters. This is a great night to observe two of the greatest craters on the Moon, Tycho and Copernicus, as the terminator is nearby.

  • Claire Bretherton from the Carter Observatory in New Zealand speaks about the southern hemisphere night sky during January 2018.

    This month we will continue our tour of some of the clusters and nebulae along the Milky Way, which stretches across the eastern sky after dark, becoming brightest in the south towards the Southern Cross /Te Punga.

  • Orion still dominates our Eastern skies after dark. Just above and to the right of Sirius, at distance of around 4 degrees, is M41, or NGC 2287. M41 is an open cluster of stars, covering an area around the size of the full moon. It is just about visible as a blurry smudge to the naked eye from a clear, dark location. Through binoculars or a small telescope you will start to resolve a number of individual stars, showing hints of red and orange, including a prominent 6.3 magnitude K3 giant close to the cluster's centre.

  • Canopus. Canopus is the brightest star in the constellation of Carina, the keel, which along with Vela, the sails, and Puppis, the poop deck, once formed part of the southern constellation of Argo Navis. Straddling the Milky Way, this represented the great ship used by Jason and the Argonauts in their search for the Golden Fleece. The constellation was split into the three components used today by French Astronomer Nicolas Louis de Lacaille in 1763.

  • Eta Carina. Eta Carinae is now back to around 4th magnitude, but it is brightening again. It is expected to end its life in a huge supernova within the next few thousand years.

  • Nebulae in Eta Carinae. Also worth looking out for in Carina is NGC 2516, known as the southern beehive, located just above the false cross, and NGC 3532, the football cluster, or wishing well cluster. Both are visible to the naked eye, but a good pair of binoculars will reveal a stunning view. NGC 3532 in particular is a great target, a favourite of English astronomer John Herschel, and the very first object to be observed by the Hubble Space Telescope in May 1990. You'll find it roughly half way between Crux and the False Cross, close to Eta Carinae.

  • Planets. Mercury sits low in the morning twilight throughout most of January and is soon joined by Saturn, with the two sitting right next to each other on the morning of the 13th. Saturn continues to rise higher whilst Mercury, on its inner orbit, sinks back into the twilight.

  • Wishing you clear skies, and a very happy 2018, form the team here at Space Place at Carter Observatory.

    Compiled by Ian Morison


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