Night Sky Notes January 2017

Night Sky Notes for January 2017                         Geoff Mitchell

The January night sky now sees some familiar winter constellations and the bright planet Jupiter rising by late evening.  The winter night sky contains many fine objects to view with both binocular and small telescopes.

Venus shines brightly in the south west after sunset, small telescopes show the phase to be just over 50 % in early January.  Venus reaches greatest elongation east of the Sun and hence 50% phase or Dichotomy occurs around the 12th January.  It is fun to estimate the phase by drawing the phase at the eyepiece and measuring the position of the terminator as a fraction of the diameter using a ruler. The Schroter effect named after Johann Schroter in 1793 can influence how an observer preserves the position of the terminator, Venus appearing slightly concave around half phase.

The red planet Mars is also visible low in the south west, presenting a tiny telescopic image. Mars returns to favourable opposition in July 2018.

The constellations of Cygnus and Lyra can be seen slipping into the west early evening; these are noted for the bright stars of Deneb and Vega which appear low in the north by late evening , both stars are circumpolar , i.e. are above the horizon from UK latitude .

The Milky Way stretches from the constellation of  Auriga , marked by the bright star Capella in the east up into Perseus  and through the `W` shaped constellation of Cassiopeia high overhead and down along the cross shaped constellation of Cygnus  low in the west . This faint band of stars best seen on dark moonless evenings

Auriga has the bright star Capella, which is circumpolar from UK latitudes and so is always visible. The constellation of Auriga contains some nice star fields and star clusters visible in binoculars.

In the south west  the constellation of Pegasus, noted for its `Square ` shape and the adjacent constellation of Andromeda noted for The Andromeda Galaxy (M31) , visible to the unaided eye as a faint fuzzy patch on moonless evening  can now be seen mid evening .  The Square of Pegasus is a useful sign post constellation and also is a good test for sky conditions, (how many faint stars you see within the square is indicates just how good your seeing conditions are).  Follow the two end stars (Scheat and Markab) down to find the star

In the north Ursa Major, The Plough or The Great Bear is seen low with its handle or tail parallel to the horizon mid evening.   Use the right hand pair of stars Dubhe and Merak (The pointers) to find the faint pole star Polaris and hence the position of North.

Look to the east early evening to see the seven sisters’ (Pleiades, M45) star cluster and constellation Taurus .The Hyades star cluster makes the characteristic `V` shaped asterism in the constellation of Taurus and is noted for the bright, red foreground star Aldebaren in Arabic Al Dabaran is `The follower ` of the Pleiades across the skies `, in old English known as Oculus Tauri, `the eye of the bull`.  Also in Taurus is the famous `Crab Nebula` M1, the first object catalogued by French astronomer Charles Messier, it is a remnant from a supernova explosion witnessed by Chinese observers in AD1054. Telescopically it looks like a grey oval shaped nebula, but larger instruments show some detail ie extensions that give it its name, looking like the claw of a crab. At the centre of the Crab Nebula is a rapidly rotating pulsar star, the remains of the supernova, surrounded by the expanding shell of gas that is the Crab Nebula.

By  mid evening the familiar winter constellations of Orion (The Hunter) is rising  with bright red star Betelgeuse (top left) , white star Rigel (bottom right ) and the three stars of Orion’s  belt Mintaka , Alnilam and Alnitak  . Below Orion’s belt can be seen the misty patch that is M42 / M43, visible to the unaided eye, it is one of the gem’s of the winter skies when seen with a telescope. This nebula some 30 light years across is illuminated by a group of four hot young stars that is known as the `Trapezium `asterism, visible under moderate magnification.

The Quadrantids meteor shower reaches maxima in the afternoon of January 3rd. Favourable moonlight, dark sky conditions may give a reasonable chance of seeing these blue/ yellow meteors on evenings over the period January 1st to January 6th .

 

Planets in January 2017

Mercury is low in dawn skies reaching greatest elongation west of the Sun on January 19th.

Venus sets several hours after the Sun, visible low in evening twilight its phase reducing to 42% by late January.

Earth reaches perihelion, its closest point in its orbit to the Sun on January 4th distance 147,100,998 km.

Mars is visible low in twilight evening skies, its apparent size just 5.2” by late January. (poor)

Jupiter shines brightly in the east by midnight at the end of the month, returning to early evening skies by March.

Saturn is positioned low in dawn skies in January in the constellation of Ophiuchus. An evening object by May.

Uranus is visible early evening in the constellation of Pisces. (Binocular / Telescope required).

Neptune is located in Aquarius (Binocular / Telescope required). The constellation of Aquarius is positioned low in the west; Mars and Neptune have a close conjunction on Jan 2nd (0.02°)

Moons phases in January  2017

New Moon         Jan 28th               Moonless, best time for deep sky observing.

First Quarter      Jan 8th                   Best days to see shadow details in lunar craters (early evening)

Full Moon            Jan 12th                 Best days to see bright ray craters like Copernicus / Tycho.

Last Quarter      Jan 18th               Moon visible in daytime skies.  Do not look directly at the Sun.

Meteor showers

Quadrantids range Jan 1st to Jan 6th, Max Jan 4th ZHR 80 / hour – very favourable.

The highlights of the month

Venus and Mars in twilight skies, Venus is half phase around greatest elongation January 12th

Milky Way visible high overhead on moonless evenings in darker skies.

M31 the Andromeda Galaxy is visible on moonless evenings, best seen in binoculars.

Double cluster, on the Perseus /Cassiopeia border, nice pair of star clusters.

Pleiades (Seven Sister’s) star cluster (M45) rising in the east best seen with binoculars.

Orion Nebula (M42) is a beautiful sight seen telescopically.

Beehive cluster (M44) visible to the unaided eye but best seen with binoculars.

Crescent Moon visibility:

  • ultra thin (0.6%) moon just 17 hours after new Moon (Jan 28th, 5pm, after sunset)
  • Jan 29th a thin 3% crescent Moon visible after sunset, moonset 6.41 pm.

(Caution , always wait until the sun has completely set below the horizon before looking for crescent Moon )

 

More detailed sky notes and LAS Newsletters, Finder charts are available to LAS members via the Members` page on the LAS Website www.lutonastrolink.org.uk

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