Dundee Astro - Sky Notes

January 1st.    sunrise    0846 UT          sunset 1545 UT
January 15th   sunrise    0835 UT         sunset 1607 UT
January 31st    sunrise    0810 UT        sunset   1641 UT

In mid-January, the sky is reasonably dark between 1730 and 0700 UT.

The Sun travels through the zodiacal constellation of Sagittarius for the first part of January, moving into neighbouring Capricornus on Sunday 19th.

The Earth is at perihelion – the closest point to the Sun on its annual orbit – on Saturday January 4th, when it lies at a distance of 91.4 million miles (147 million kilometres). This is around 3% closer than at its most distant in July.

The Moon is a narrow, young waxing crescent at the start of January, becoming visible low above the south-west horizon after sunset from Thursday 2nd onwards. On the evening of Friday 3rd, the crescent Moon will appear about 2˚ to the lower left of the bright planet Venus; on the following evening, Saturday 4th, the Moon will be very close to Saturn, and will actually occult the planet between 1720 and 1828 UT (see below for more details). The Moon will then slowly move away to the upper left of Saturn.

First Quarter is on the evening of Monday January 6th; the half-illuminated Moon will appear high in the south as the sky grows dark.

On the evening of Thursday 9th, the gibbous Moon will lie just to the lower left of the Pleiades star cluster, and will cross the south-eastern part of the cluster in the early hours of the morning, occulting several of its brightest stars. On the next night, Friday 10th, the Moon will lie just above the planet Jupiter.

Full Moon falls on the evening of Monday January 13th. The Moon rises in the north-east over an hour before sunset, shines high in the south at midnight and sets again in the north-west an hour after sunrise. The Moon will appear close to the planet Mars throughout the night.

Last Quarter is on the evening of Tuesday January 21st; the half-illuminated Moon rises in the south-east in the early hours of the morning and is low in the south at dawn.

The narrowing crescent Moon may be followed into the dawn twilight up until the morning of Saturday 25th.

New Moon is on Wednesday January 29th, and the young crescent Moon will become visible low in the south-west again from Friday 31st onwards. On that evening, the narrow Moon will appear to the lower right of the planets Saturn and Venus.

Mercury is rising about 1½ hours before the Sun in early January and appears very low above the south-east horizon at dawn. However it is now moving back in towards the Sun and is a little lower each morning; by the middle of the month it will be lost in the bright dawn twilight.

Venus is at its greatest elongation from the Sun on January 10th and appears as a dazzling ‘Evening Star’ of magnitude -4.5 above the south-west horizon at sunset, setting well over four hours after the Sun.

Mars reaches opposition on January 16th, when it will shine as a magnitude -1.4 orange ‘star’ low in the east at sunset and almost 60˚ high in the south around midnight. During January, Mars is also moving retrograde – from east to west against the background stars – and travels from the constellation of Cancer into Gemini, ending the month to the lower right of the bright stars Castor and Pollux (the position of Mars on the star chart below is shown for mid-month). However, this is a rather unfavourable opposition, with Mars only approaching to just under 60 million miles from the Earth and showing at best a disc of just over 14 seconds of arc (oppositions of Mars vary over a 15- to 17-year cycle, and at more favourable oppositions - such as those of 2018 and 2035 - it can approach to within 35 million miles and appear over 24” in diameter).

Jupiter shines brightly and steadily at magnitude -2.6 in the south-east as the sky grows dark and is around 55˚ high in the south around mid-evening, lying among the stars of Taurus.

Saturn is low in the south-west in the evening twilight, at magnitude 1.1, and by the end of the month is setting around 2000 UT. It gradually approaches Venus as the month progresses, with the two planets appearing just 2˚ apart at their closest on the night of Saturday 18th; after this, Venus gradually draws away to the upper left of Saturn.

Uranus lies in eastern Aries about 18˚ to the west of Jupiter and 8o to the south-west of the Pleiades, and is easily seen in binoculars at magnitude 5.7.

Neptune is at magnitude 7.9 in south-west Pisces, about 12˚ north-east of Saturn; Venus also comes to within 3o of Neptune in the closing days of January.

OCCULTATION OF SATURN

The Moon will pass directly in front of the planet Saturn and occult it on the early evening of Saturday 4th January, when both objects will be in the south-south-west. At Dundee, Saturn disappears at 1720 UT with the Moon 24˚ high; reappearance is just over an hour later at 1828 UT when the Moon will be 20˚ up.

The annual Quadrantid meteor shower peaks on Friday January 3rd. The shower has a very sharp maximum, and although this is predicted to fall around midday this year, high meteor rates may be seen between midnight and dawn that morning, and possibly also during the following evening. With the Moon just a narrow crescent in the evening sky, there will be no interference this year from moonlight and rates of 40-50 meteors per hour are possible.

The Quadrantids take their name from the now-discarded constellation of Quadrans Muralis, the Mural Quadrant; the radiant point that the meteors seem to radiate out from lies near the handle of the Plough, which is low in the north during the evening and highest in the north-east at dawn.

January evenings sparkle with a spectacular array of stars – a single glance to the south takes in five of the ten brightest stars in the entire night sky, including Sirius, the brightest of them all.

Centrepiece of this dazzling celestial panorama is the large and distinctive outline of Orion the Hunter, with his central belt of three stars, shoulders above and knees below. The red giant star Betelgeuse marks his left shoulder, and blue-white Rigel his right knee. Following the line of the belt stars upwards to the right leads to the orange star Aldebaran in the V-shaped head of Taurus the Bull; a little further along this line is the star cluster of the Pleiades or Seven Sisters. This winter, the planet Jupiter makes a bright addition to the stars of Taurus.

Orion’s belt points downwards to Sirius, often known by its nickname, the Dog Star. As well as being the brightest of the night-time stars, Sirius is also one of the closest, lying about 8.5 light years away – around 50 million million miles. Although it is actually a white star, Sirius always twinkles strongly, appearing to flash different colours as it does so.

The Square of Pegasus and the stars of Andromeda are in the south-west, with the ‘W’ of Cassiopeia just above. Below Andromeda are the small but notable constellations of Triangulum and Aries, the Ram. Low in the south-west is the large and rather faint outline of Cetus, the Whale.

Almost overhead are the stars of Perseus and Auriga, while the zodiacal constellation of Gemini with its twin stars Castor and Pollux is high in the south-east, this January joined by orange Mars. Below Gemini is the bright star Procyon, often referred to as the ‘little Dog Star’. Low in the east is Leo, with the bright star Regulus at the bottom of the distinctive ‘Sickle’ of stars representing the Lion’s head.

The seven stars of the Plough are in the north-east, the two ‘pointer’ stars showing the way to the Pole Star; low in the north-west are the stars Deneb in the cross-shaped constellation of Cygnus the Swan, and Vega in the small group of Lyra, the Lyre.

The Milky Way appears as a faint band of light, stretching from Deneb in the north-west, overhead through Cassiopeia, Perseus and Auriga, and into the south-east between Orion and Gemini. January evenings are among the best of the year for exploring the winter Milky Way with binoculars and small telescopes.