Mercury at superior solar conjunction

Sat, 17 Feb 2018 at07:12 EST(10 hours ago)
12:12 UTC

Dominic Ford, Editor
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The sky at

Mercury will pass very close to the Sun in the sky as its orbit carries it around the far side of the solar system from the Earth.

This occurs once in every synodic cycle of the planet (116 days), and marks the end of Mercury's apparition in the morning sky and its transition to become an evening object over the next few weeks.

At closest approach, Mercury will appear at a separation of only 1°58' from the Sun, making it totally unobservable for several weeks while it is lost in the Sun's glare.

Mercury will also pass apogee – the time when it is most distant from the Earth – at around the same time, since it will lie exactly opposite to the Earth in the Solar System. It will move to a distance of 1.38 AU from the Earth, making it appear small and very distant. If it could be observed, it would measure 4.9 arcsec in diameter, whilst appearing completely illuminated.

The exact position of Mercury at the moment it passes solar conjunction will be:

Object Right Ascension Declination Constellation Angular Size
Mercury 22h05m30s -13°50' Aquarius 4.9"
Sun 22h02m -11°59' Aquarius 32'22"

The coordinates above are given in J2000.0.

The sky on 17 February 2018
Sunrise 06:58
Sunset 17:47
Twilight ends
Twilight begins

2-day old moon
Age of Moon
2 days

All times shown in EST.
Rise Culm. Set
Mercury 07:09 12:26 17:43
Venus 07:30 13:01 18:31
Moon 08:08 13:49 19:30
Mars 02:20 07:07 11:54
Jupiter 00:36 05:41 10:46
Saturn 04:01 08:46 13:31


Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.


The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).

This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.

Related news

01 Jan 2018, 19:40 EST  –  Mercury at greatest elongation west
15 Mar 2018, 06:18 EDT  –  Mercury at greatest elongation east
29 Apr 2018, 11:06 EDT  –  Mercury at greatest elongation west
12 Jul 2018, 00:00 EDT  –  Mercury at greatest elongation east

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