Our celestial neighbourhood in January

PICK OF THE MONTH: Venus

Best time to see: 31 January, 07:00 UT Altitude: 9˚ (low)
Location: Sagittarius
Direction: Southeast
Features: Phase, faint shaded markings.
Recommended equipment: 75mm, or larger

Venus is in its crescent phase this month. You might be fortunate enough to catch the planet in the evening sky right at the month’s start, but it’s heading for inferior conjunction on 9 January so you don’t have long. On the 1st, a telescope will show Venus as a slender 2%-lit crescent, a remarkable sight if you have clear skies. Being thin and low in altitude, this crescent is susceptible to the unstable atmosphere we have to look through for objects close to the horizon, so plan to catch it as early as you can after sunset. As ever, be safe when hunting for Venus and make sure the Sun is below the horizon before looking for it. If you’re more experienced, it is possible to locate Venus during the day when the Sun is up, but as it’s getting close to the Sun now, this is not recommended unless you know what you’re doing.

Following inferior conjunction on the 9th, Venus rapidly re-emerges into The planets in January the morning sky, greatly assisted by the planet being north of the ecliptic plane – the plane of Earth’s orbit around the Sun, which also marks out the apparent path of the Sun against the background stars.

On 14 January, a telescope will reveal Venus as a 1%-lit crescent, 1 arcminute across. This is at the limit of resolution for the human eye. On this date the planet rises an hour before the Sun. By the 14%-lit, its apparent diameter having shrunk to 49 arcseconds. Observing Venus will have time the end of the month has arrived, the phase of Venus will have increased to become a little easier too, the planet now rising 135 minutes before the Sun.

---

Mercury

Best time to see: 7 January, 30 minutes after sunset
Altitude: 8˚ (low)
Location: Capricornus
Direction: Southwest Mercury shines at mag. –0.7 in the evening twilight at the month’s start when it sets, with Venus, about 80 minutes after sunset. It reaches greatest eastern elongation on the 7th, setting 100 minutes after the Sun, but dimming to mag. –0.5. The dimming continues and on the 13th, now shining at mag. +0.4, Mercury appears 3.4˚ from mag. +0.9 Saturn.

Mars

Best time to see: 31 January, 07:15 UT Altitude: 6˚ (low)
Location: Sagittarius
Direction: Southeast Mars is a morning planet at the start of 2022, rising two hours before the Sun on the 1st when mag. +1.5 Mars lies 5.5˚ from its sky rival Antares (Alpha (α) Scorpii). This offers a good opportunity to compare the planet with its mag. +1.0 stellar rival; the name Antares means ‘rival of Mars’. Mars never gains much altitude under January’s brightening dawn.

Jupiter

Best time to see: 1 January, 17:00 UT
Altitude: 23˚
Location: Aquarius
Direction: South-southwest Jupiter is a bright evening planet, visible from 17:00 UT at January’s start, 23˚ above the south-southwest horizon. It shines at mag. –2.0. A waxing crescent Moon passes near Jupiter on the evenings of the 5th and 6th. By the end of January, Jupiter appears against the dusk twilight as its evening observational window draws to a close.

Saturn

Best time to see: 1 January, 17:00 UT
Altitude: 12˚
Location: Capricornus
Direction: Southwest Saturn is an evening planet, but not well placed, affected by the evening post-sunset twilight glow. Mag. +0.9 Saturn is joined by mag. –0.6 Mercury and a thin 5%-lit waxing crescent Moon on 4 January. Look for the trio 80 minutes after sunset. Venus is there too, but closer to the Sun. Jupiter completes the line-up, following 19˚ to the east. Mercury appears 3.6˚ from Saturn on the 14th. On this date Mercury and Saturn appear similar in brightness.

Uranus

Best time to see: 1 January, 20:00 UT
Altitude: 52˚
Location: Aries
Direction: South Uranus is well placed at the month’s start, reaching over 50˚ altitude when due south, as seen from the UK’s centre. But the planet’s visibility degrades towards the month’s end. Uranus shines on the edge of naked-eye visibility at mag. +5.7 in southern Aries.

Neptune

Best time to see: 1 January, 18:15 UT
Altitude: 30˚
Location: Aquarius
Direction: South-southwest On the 1st, mag. +7.9 Neptune is about 30˚ above the south-southwest horizon as darkness falls. By the month’s end, this value will have decreased to 15˚. Optical assistance is required to spot Neptune, the minimum equipment being binoculars.

More ONLINE

Print out observing forms for recording planetary events

The planets in January

The phase and relative sizes of the planets this month. Each planet is shown with south at the top, to show its orientation through a telescope

Jupiter’s moons: January

Using a small scope you can spot Jupiter’s biggest moons. Their positions change dramatically during the month, as shown on the diagram. The line by each date represents 00:00 UT.