Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Nov–Dec 2085 morning apparition. It will be shining brightly at mag -0.4.

From Cambridge , this apparition will be exceptionally well placed but tricky to observe, reaching a peak altitude of 17° above the horizon at sunrise on 24 Nov 2085.

Nov–Dec 2085 morning apparition of Mercury

07 Nov 2085 – Mercury at inferior solar conjunction
21 Nov 2085 – Mercury at dichotomy
22 Nov 2085 – Mercury at highest altitude in morning sky
23 Nov 2085 – Mercury at greatest elongation west
05 Jan 2086 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

19 Jun 2085 – Evening apparition
05 Aug 2085 – Morning apparition
15 Oct 2085 – Evening apparition
23 Nov 2085 – Morning apparition
06 Feb 2086 – Evening apparition
20 Mar 2086 – Morning apparition
31 May 2086 – 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 14h30m30s 12°15'S Libra 7.2"
Sun 15h45m 19°48'S Libra 32'22"

The coordinates above are given in J2000.0.

The sky on 16 Jun 2024

The sky on 16 June 2024
Sunrise
05:04
Sunset
20:23
Twilight ends
22:38
Twilight begins
02:49


Waxing Gibbous

75%

10 days old

Planets
Rise Culm. Set
Mercury 05:11 12:54 20:36
Venus 05:19 12:57 20:36
Moon 15:06 20:38 02:00
Mars 02:27 09:16 16:05
Jupiter 03:51 11:14 18:37
Saturn 00:45 06:26 12:06
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

07 Nov 2085  –  Transit of Mercury
23 Nov 2085  –  Mercury at highest altitude in morning sky
23 Nov 2085  –  Mercury at greatest elongation west
06 Feb 2086  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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