January’s skies are the darkest, clearest and longest of the year where some of the most prominent and beautiful stars can be found. Vernon from the Callander and West Perthshire U3A Astronomy group shares what to look out for this month.
It is always helpful to have a star chart to follow when navigating and observing the heavens. A free star chart which also contains lots of additional observational notes is published monthly by Skymaps. Simply go to skymaps.com and scroll down to ‘Download the latest issue’. From here you will can download the northern hemisphere version and save it. This is then best printed double sided to an A4 sheet. It is worth noting that planets do not appear on skymaps. In this note of astronomical events I have only included items that can be seen either with the naked eye or with a pair of binoculars.
Should you venture outside you will need a torch. Use a red light head torch if you have one, or put red plastic over a torch to illuminate the skymap and preserve your night vision which improves greatly over time. Wrap up warm and with a little perseverance, about 20 minutes, you will feast your eyes on the universe that you live within. Enjoy and indulge!
Orion, the Hunter, is high in the southern sky with its bright red star Betelgeuse as his right shoulder and an even brighter white/blue star Rigel as his left foot. The clear to see three stars forming Orion’s belt have three stars hanging below which form the sword. The fuzzy patch behind the sword is the Orion Nebula also called M42 after French astronomer and cataloguer Messier who identified a total of 110 astronomical objects in 1774. The Orion Nebula is just visible to the naked eye and readily seen with binoculars. It is 1,344 light years away and is a star forming nursery. Taurus lies to the northwest of Betelgeuse, and so do the beautiful Pleiades and Hyades star clusters which make excellent subjects for binoculars. Orion’s dogs, Canis Major and Canis Minor, trail east of the hunter. The phrase “the dog days of summer”, when it is hot and sultry comes from the Dog Star, Sirius, which rises alongside the sun in summer. Ancient people believed the two stars together brought additional heat to the Earth. Sirius, brightest star in the night sky, even though twice the mass and just under twice the diameter of the Sun and puts out 26 times as much energy, is over 8.5 light years from the Earth so is too distant to have any seasonal influence.
Looking due north, the US Asterism “The Big Dipper”, (Plough in the UK), is a part of a much larger constellation Ursa Major, the Great Bear. Ursa Major is the third largest constellation and has been recognised as a bear by many civilisations since ancient times. The seven brightest stars form the body and tail and the 13 fainter stars form the legs and head. The Plough’s two brightest stars Merak and Dubhe are important signposts as they direct the observer to the pole star Polaris. Try identifying the star Mizar from the chart on Skymap.com and then look northwards at Mizar carefully through your naked eye. Mizar has a remarkably close neighbour, Alcor, which can just be seen if you are careful and persistent.
For navigation purposes it can be important to see the North Star, Polaris, but this is only the 48th brightest star in the sky. Identifying the pointer stars Mizar and Alcor are the only clear and certain route. Polaris is in the constellation of Ursa Minor, the most northern constellation in the sky. It is made up of seven moderately bright stars and has a pattern similar to the Plough. Should you wish to venture into the field of astrophotography this is probably a good place to begin. By focussing on Polaris and setting a long exposure you will achieve a stunning picture of Polar Trails where all the stars describe arcs while the central star, Polaris, remains at the centre. To the west of Ursa Minor there are good views of Cephus and Cassiopeia with Camelopardalis looking down from above.
Mercury is visible in the west shortly after sunset using great care just 13 degrees from the sun.
Venus the morning star starts the month sitting 20 degrees above the eastern horizon becoming a little lower each day.
Earth reaches its closest point to the Sun (perihelion) on the 2nd at 0.9833 au or 147,100,000 km.
Mars helpfully is not setting until after midnight this month but it is getting gradually fainter each evening. It can be found early in the month in Pisces and then moves into Aries.
Jupiter and Saturn following last months Great Conjunction are now drifting apart with Jupiter leading. They are now too close to the Sun to be observed.
Uranus is present in the evening and early hours sitting in the constellation of Aries.
Neptune is above the horizon and remains in Aquarius throughout 2021.
Eunomia is one of five minor planets that can be seen this year. Observations can be made when the minor planets are in opposition and become bright enough to see. Eunomia is in opposition on the 21st and can be found in the constellation of Cancer. The other four minor planets that can be see later in the year are Vesta in March, Hebe in July, Pallas in September and Ceres, the dwarf planet, in November.
The Quadrantids, 3rd & 4th, have a maximum hourly rate of 120 can be observed in the constellation of Bootes. They originate from Asteroid 2003EH.
Nights of interest
Some of the objects described below are expressed in degrees from the Moon. This is far less complicated to measure than you might think. To measure 10 degrees, hold your hand up towards the sky at arm’s length and turn your hand up so that it obscures part of your view. The width of your hand is 10 degrees and holding just one finger is two degrees.
2nd Jan 13.51 Earth at perihelion 0.983257 AU, 147,093,163 km from the Sun
3rd & 4th Jan Quadrantids meteor shower peak, maximum hourly rate of 120 meteors.
6th Jan 09.37 Last quarter of Moon
9th Jan 15.37 Moon at perigee, nearest to Earth (367,387 km)
9th Jan 21.00 Mercury 1.7 degrees south of Saturn
11th Jan 11.00 Mercury 1.5 degrees south of Jupiter
13th Jan 20.52 New Moon
17th Jan Crescent Moon forms triangle with Neptune and star Psi Aquarii
17th Jan 06.14 Neptune 4.5 degrees north of the Moon
21st Jan 05.37 Mars and Uranus in conjunction to the right of the Moon
21st Jan 18.37 Eunomia is in opposition in the constellation of Cancer (8.5 mag)
21st Jan 13.11 Moon at apogee, farthest from Earth (404,360 km)
23rd Jan Moon passes between Pleiades and Hyades Clusters
24th Jan 03.11 Saturn in conjunction with the Sun
28th Jan 19.16 Full Moon
29th Jan 01.40 Jupiter in conjunction with the Sun