Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Nov–Dec 2111 morning apparition. It will be shining brightly at mag -0.4.

From Fairfield , this apparition will be exceptionally well placed but tricky to observe, reaching a peak altitude of 17° above the horizon at sunrise on 30 Nov 2111.

Nov–Dec 2111 morning apparition of Mercury

13 Nov 2111 – Mercury at inferior solar conjunction
27 Nov 2111 – Mercury at dichotomy
29 Nov 2111 – Mercury at highest altitude in morning sky
30 Nov 2111 – Mercury at greatest elongation west
13 Jan 2112 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

26 Jun 2111 – Evening apparition
12 Aug 2111 – Morning apparition
22 Oct 2111 – Evening apparition
30 Nov 2111 – Morning apparition
12 Feb 2112 – Evening apparition
26 Mar 2112 – Morning apparition
07 Jun 2112 – 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 14h48m40s 13°36'S Libra 7.2"
Sun 16h05m 20°49'S Scorpius 32'24"

The coordinates above are given in J2000.0.

The sky on 25 May 2024

The sky on 25 May 2024
Sunrise
05:23
Sunset
20:13
Twilight ends
22:14
Twilight begins
03:23


Waning Gibbous

91%

17 days old

Planets
Rise Culm. Set
Mercury 04:34 11:27 18:20
Venus 05:19 12:37 19:55
Moon 21:55 02:14 06:32
Mars 03:24 09:49 16:14
Jupiter 05:13 12:28 19:43
Saturn 02:17 07:57 13:38
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 Nov 2111  –  Transit of Mercury
29 Nov 2111  –  Mercury at highest altitude in morning sky
30 Nov 2111  –  Mercury at greatest elongation west
12 Feb 2112  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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