© NASA/JPL/MESSENGER

Mercury at inferior solar conjunction

Dominic Ford, Editor
From the Inner Planets feed

Objects: Mercury
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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°53' 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 0.66 AU from the Earth, making it appear with its largest angular size. If it could be observed, it would measure 10.2 arcsec in diameter, whilst appearing completely unilluminated.

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

Object Right Ascension Declination Constellation Angular Size
Mercury 12h57m00s 8°09'S Virgo 10.2"
Sun 13h00m 6°24'S Virgo 32'01"

The coordinates above are given in J2000.0.

The sky on 9 Oct 2021

The sky on 9 October 2021
Sunrise
06:48
Sunset
18:11
Twilight ends
19:45
Twilight begins
05:14

3-day old moon
Waxing Crescent

18%

3 days old

Planets
Rise Culm. Set
Mercury 06:54 12:27 18:00
Venus 10:56 15:27 19:58
Moon 10:34 15:29 20:17
Mars 06:46 12:29 18:12
Jupiter 16:02 21:08 02:14
Saturn 15:17 20:05 00:54
All times shown in EDT.

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 DE430 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

13 Sep 2021  –  Mercury at greatest elongation east
25 Oct 2021  –  Mercury at highest altitude in morning sky
24 Oct 2021  –  Mercury at greatest elongation west
07 Jan 2022  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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Longitude:
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42.38°N
71.11°W
EDT

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