Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

Objects: Mercury
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Mercury will reach half phase in its Feb–Mar 1995 morning apparition. It will be shining brightly at mag 0.1.

From Ashburn , this apparition will not be one of the most prominent and very difficult to observe, reaching a peak altitude of 12° above the horizon at sunrise on 20 Feb 1995.

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Feb–Mar 1995 morning apparition of Mercury

03 Feb 1995 – Mercury at inferior solar conjunction
22 Feb 1995 – Mercury at highest altitude in morning sky
24 Feb 1995 – Mercury at dichotomy
01 Mar 1995 – Mercury at greatest elongation west

A graph of the phase of Mercury is available here.

Apparitions of Mercury

26 Sep 1994 – Evening apparition
05 Nov 1994 – Morning apparition
19 Jan 1995 – Evening apparition
01 Mar 1995 – Morning apparition
11 May 1995 – Evening apparition
29 Jun 1995 – Morning apparition
08 Sep 1995 – Evening apparition

Observing Mercury

Mercury's orbit lies closer to the Sun than the Earth's, meaning that it always appears close to the Sun and is lost in the Sun's glare much of the time.

It is observable for only a few weeks each time it reaches greatest separation from the Sun – moments referred to as greatest elongation. These apparitions repeat roughly once every 3–4 months.

Mercury's phase

Mercury's phase varies depending on its position relative to the Earth. When it passes between the Earth and Sun, for example, the side that is turned towards the Earth is entirely unilluminated, like a new moon.

Conversely, when it lies opposite to the Earth in its orbit, passing almost behind the Sun, it appears fully illuminated, like a full moon. However, at this time it is also at its most distant from the Earth, so it is actually fainter than at other times.

Mercury shows an intermediate half phase – called dichotomy – at roughly the same moment that it appears furthest from the Sun, at greatest elongation. The exact times of the two events may differ by a few days, only because Mercury's orbit is not quite perfectly aligned with the ecliptic.

Mercury's position

The coordinates of Mercury when it reaches dichotomy will be:

Object Right Ascension Declination Constellation Angular Size
Mercury 20h47m10s 17°21'S Capricornus 7.6"
Sun 22h31m -09°17' Aquarius 32'19"

The coordinates above are given in J2000.0.

The sky on 28 January 2022
Twilight ends
Twilight begins

26-day old moon
Waning Crescent


26 days old

Rise Culm. Set
Mercury 06:26 11:31 16:36
Venus 05:14 10:23 15:31
Moon 03:57 08:44 13:27
Mars 05:11 09:50 14:29
Jupiter 08:41 14:10 19:40
Saturn 07:43 12:48 17:53
All times shown in EST.


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

22 Feb 1995  –  Mercury at highest altitude in morning sky
01 Mar 1995  –  Mercury at greatest elongation west
09 May 1995  –  Mercury at highest altitude in evening sky
11 May 1995  –  Mercury at greatest elongation east

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