© NASA/JPL/MESSENGER

Mercury at inferior solar conjunction

Tue, 12 Dec 2017 at20:43 EST(Tomorrow)
01:43 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 between the Sun and Earth.

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

At closest approach, Mercury will appear at a separation of only 1°43' from the Sun, making it totally unobservable for several weeks while it is lost in the Sun's glare.

Mercury will also pass perigee – the time when it is closest to the Earth – at around the same time, since it will lie on exactly the same side of the Sun as the Earth in the Solar System. It will move to within a distance of 0.68 AU from the Earth, making it appear with its largest angular size. If it could be observed, it would measure 9.9 arcsec in diameter, whilst appearing completely unilluminated.

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

Object Right Ascension Declination Constellation Angular Size
Mercury 17h21m10s -21°24' Ophiuchus 9.9"
Sun 17h20m -23°07' Ophiuchus 32'29"

The coordinates above are given in J2000.0.

The sky on 12 December 2017
Sunrise 07:18
Sunset 16:46
Twilight ends
18:22
Twilight begins
05:42

24-day old moon
Age of Moon
24 days

All times shown in EST.
Rise Culm. Set
Mercury 07:18 12:06 16:55
Venus 06:48 11:34 16:20
Moon 01:56 07:52 13:47
Mars 03:17 08:43 14:10
Jupiter 04:14 09:28 14:41
Saturn 07:53 12:38 17:23

Warning

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.

Source

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

23 Nov 2017, 21:22 EST  –  Mercury at greatest elongation east
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

Image credit

© NASA/JPL/MESSENGER

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Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EST

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