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.
The innermost planet’s best evening showing of the year for northern observers occurs during the fortnight starting 20 February. Skywatchers will get optimal views by sourcing a location that offers an unobstructed view of the horizon from west-southwest through west at the end of civil twilight, which is about 40 minutes after sunset for the heart of the British Isles.
Mercury attains a greatest easterly elongation of 18 degrees from the Sun on 15 March, the innermost planet’s best evening showing for Northern Hemisphere observers for the entire year. From 12–20 March, planets Mercury and Venus remain just 4 degrees apart low in the west 45 minutes after sunset as seen from the British Isles.
Have you ever seen Mercury with the naked eye? If not, now is the time to check the elusive innermost planet off your list. Mercury reaches greatest easterly elongation from the Sun on Monday, 18 April, the highlight of a very favourable dusk apparition in the west-northwest for observers in Western Europe and the British Isles.
Even casual observers cannot fail to notice dazzling Venus currently gracing the western horizon at dusk. Owing to a favourable set of circumstances, the brightest planet is visible long after sunset. How late can you see it set in the British Isles? For those north of the Arctic Circle, Venus is presently circumpolar and doesn’t set at all!