For three evenings from 26–28 February 2020, observers in Western Europe including the British Isles can watch the waxing crescent Moon’s changing configuration with brightest planet Venus in the west-southwest at dusk. The pair are closest for UK-based observers on the evening of Thursday, 27 February, simultaneously visible in low-power binoculars.
Mercury is poised to put on a fine evening show for Northern Hemisphere observers at dusk, attaining a greatest elongation 18.2 degrees east of the Sun on Monday, 10 February 2020. For ten evenings starting 3 February, the innermost planet and its brightest sibling, Venus, maintain an almost constant angular separation low in the west-southwest 40 minutes after UK sunset.
At around magnitude +9, C/201 W2 (Africano) is the brightest comet currently on show, passing closest to Earth on 27 September slightly less than half an astronomical unit away. Speeding through the constellations of Pegasus, Pisces and Aquarius, Comet Africano also lies within a binocular field of view of outermost planet Neptune on the night of 3–4 October.
Mercury attains a very favourable western elongation of almost 28 degrees from the Sun on 11 April, which means that the innermost planet is a morning object in the eastern sky before sunrise. Antipodean skywatchers are in the enviable position of being able to see Mercury and Venus close together for several mornings in a dark sky before the onset of astronomical twilight.
Have you ever seen planet Uranus? If skies are clear in the UK and Western Europe on the evening of Sunday, 10 February, see this icy gas giant less than 2 degrees (or four lunar diameters) from Mars and 6 degrees from the 5-day-old crescent Moon. In fact, you’ll see all three in a single view of wide-angle binoculars like 7×50s.
Observers should direct their gaze to the southern sky at dusk on Saturday, 12 January to view the 6-day-old waxing Moon in the constellation of Pisces. Look a little closer around 6pm GMT in the UK this night to see Mars as a magnitude +0.6 orange-coloured ‘star’ above the lunar crescent. If you own wide-angle 7× or 8× binoculars, you can see the Moon and Red Planet in the same field of view.
Have you ever seen the closest planet to the Sun? If you wish to tick Mercury off your To-See list, particularly if you live in the Southern Hemisphere, now until the middle of May is the time to be scrutinising the eastern sky about an hour before sunrise. Mercury also has a close encounter with an old crescent Moon on 14 May.
As shooting-star devotees prepare for the naked-eye spectacle of the Geminid meteor shower in mid-December, owners of small telescopes can also witness the close passage of the meteors’ parent body — a curious “rock comet” known as 3200 Phaethon, galloping through the constellations of Auriga, Perseus, Andromeda, Pisces and Pegasus at a rate of up to 15 degrees/day.
Mercury attains a greatest easterly elongation of 19 degrees from the Sun on 1 April. This solar separation combined with a favourable inclination of the ecliptic to the western horizon an hour after sunset, means that the period 25 March to around 8 April offers the year’s best evening showing of the innermost planet for Northern Hemisphere observers.