The Night Sky This Month: January 2017

Tycho and Copernicus on the Moon
Image Credit: Frank Barrett/celestialwonders.com

Happy New Year! January 2017 offers stargazers an opportunity to see the winter sky’s most prominent constellations, as well five planets, and a wonderful meteor shower called the The Quadrantids. Here’s our monthly guide that will help you know exactly what to look out for in the coming weeks.

Constellations

Orion, can be observed towards the south around midnight, and acts as a useful guide in locating the other Winter Constellations of Taurus, Gemini, Canis Major, Canis Minor and Auriga.

Just north-west of Orion can be found a beautiful triangular arrangement of stars called the Hyades which represents the bull’s head in the constellation Taurus, while a little further on can be seen one of the finest open star clusters in the night sky called the Pleaides. North of Orion lies Auriga, which contains Capella, the 6th brightest star in the sky; while to Orion’s north-east is the constellation of Gemini, whose two brightest stars, Pollux and Castor, depict the heads’ of the heavenly twins.

Finally, Orion’s two hunting dogs, Canis Minor and Canis Major can be found towards its east and south-east respectively, with the “lesser dog” containing Procyon, the night sky’s 8th brightest star at magnitude 0.34, and the “greater dog” containing Sirius, the brightest star in the sky at magnitude -1.46.

The Moon

The first week of January 2107 offers a wonderful opportunity to view two of the greatest craters on the Moon using binoculars, namely Tycho and Copernicus, since the terminator (dividing line between the lit and unlit part of the Moon) will be close to both craters on the 7th of the month. Tycho is difficult to miss in the Southern Lunar Highlands, while Copernicus, almost due north of Tycho, is a spectacular feature in the eastern reaches of the Oceanus Procellarum, just beyond the termination of the Apennine Mountains.

Moon Phases

First Quarter: 5th
Full Moon: 12th
Last Quarter: 19th
New Moon: 28th

The Planets

Since all the major planets are currently dipping towards the south, now would be good time for serious northern hemisphere stargazing hobbyists to invest in a good quality Atmospheric Dispersion Corrector in order to improve their views of the planets. Good quality dispersion correctors are available online for around £120 ($150) or so, which is a small price to pay to tease a planetary view from a murky atmosphere close to the horizon.

– Mercury is not visible until the 6th of the month, when it appears as a pre-dawn object shining at magnitude +0.9 to the lower south-west of the planet Saturn. Over the following week or so, the little planet will sink towards the horizon, increasing in brightness to shine at magnitude -0.2 on about the 21st of the month. Bear in mind that spotting Mercury will require the use of binoculars during much of January, so exercise care not to look for the planet when it’s too close to the Sun.

– Venus will dominate the early western sky during January, setting about 3.5 hours after the Sun, and it will reach maximum elongation (its furthest point from the Sun) at 47 degrees east of the Sun on the 12th of the month. Venus is now travelling northward along the ecliptic as it moves out of Aquarius and into Pisces, which it will reach by the 23rd. As the planet traverses the sky, it will reach a maximum elevation of about 36 degrees, and its angular diameter will increase from about 21.7 seconds of arc to about 30.4 seconds of arc, while its percentage of illumination will reduce from 57% to 40%, which means that its brightness will remain fairly constant during the month at about magnitude -4.5 or so.

– Mars starts the month in Aquarius, and moves eastward toward the southern reaches of the constellation Pisces, which it will reach on the 19th. Although the Red planet’s magnitude decreases from +0.9 to around +1.1 as the result of its angular diameter decreasing from 5.7 to 5.1 seconds of arc, it will still be easy to spot towards the upper left of Venus by the month’s end, when the two planets will be separated by a mere 5.5 degrees. However, Mars’ angular diameter will be too small to discern any surface detail during January.

– Jupiter starts the month rising at about midnight, shining at magnitude -1.9 just above the star Spica in the lower part of the constellation Virgo. By the end of January, Jupiter will be due south at an elevation of about 35 degrees, and about three degrees above Spica. As January wears on, Jupiter’s’ angular diameter increases from 35.5 to 38.9 seconds of arc, which should make it easy to spot major surface details like the equatorial bands, and even the Great Red Spot.

– Saturn passed behind the Sun in the early part of December 2016, and therefore, it is now a pre-dawn object, rising as it does about 90 minutes or so before the Sun on New Year’s Day, shining at magnitude +0.5. By the end of January, however, it will rise about 3 hours before the Sun in the southern reaches of the constellation Ophiuchus, about 15 degrees or so leftward of the star Antares in the constellation Scorpius. During January, Saturn’s magnitude will increase slightly as its angular diameter increases from 15.2 to 15.5 seconds of arc, with the ring system now spanning 35 seconds of arc. Note that even though the planets’ ring system is now inclined toward our line of sight by more than 26 degrees, great views of the system will only be possible a few months from now.

Meteor Shower

– The Quadrantids, also sometimes known as the “Bootids” after the modern constellation, Boötes, is a meteor shower associated with the asteroid 2003 EH1, which orbits the Sun once every 5.5 years. Although the Quadrantids is active between the last days of December and the second week of January, the peak is usually on the night of January 3rd/4th, and only lasts for a few hours before dawn. Nevertheless, it still produces an impressive 60 to 200 Quadrantid meteors per hour under ideal conditions.