Mercury reaches greatest elongation east (GEE) on April 18th when it's positioned 19.9 degrees from the Sun. The nearest planet to the Sun will be visible during April low down above the west-northwestern horizon shortly after sunset. This months apparition offers the best opportunity (evening) for observers at northern latitudes to spot the elusive planet this year. From equatorial regions Mercury is also visible during April but from mid-southern latitudes unfortunately not.

Observing Mercury

When searching for Mercury a clear unobstructed view of the west-northwestern horizon is essential. Observers should be able to spot the planet about 45 minutes after sunset against the twilight backdrop. What is surprising when looking for Mercury is how close the planet clings to the horizon. For example from London, England (51.5 degrees N) Mercury will be 6 degrees above the horizon 45 minutes after sunset on April 8th. On this evening the nearby thin nearby waxing crescent Moon will acts as a convenient marker. A good period to look is between April 13th and April 23rd when Mercury will be at it's highest in the sky about 10 degrees above the horizon. After that it's altitude decreases quickly until it's lost to the bright twilight near the end of the month. Observers should note that the planet is at its brightest at the start of the month - it decreases from mag. -1.4 to +2.1 as the visibility period progresses.

The diagram below shows the altitude of Mercury 45 minutes after sunset when viewed from London, England. The view will be similar from other northern temperate locations.

Mercury Data Table April 2016

See also

The Planets this Month - April 2016