Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Dec 2136–Jan 2137 morning apparition. It will be shining brightly at mag -0.3.

From Fairfield , this apparition will be well placed but tricky to observe, reaching a peak altitude of 16° above the horizon at sunrise on 21 Dec 2136.

Dec 2136–Jan 2137 morning apparition of Mercury

04 Dec 2136 – Mercury at inferior solar conjunction
18 Dec 2136 – Mercury at dichotomy
19 Dec 2136 – Mercury at highest altitude in morning sky
22 Dec 2136 – Mercury at greatest elongation west

A graph of the phase of Mercury is available here.

Apparitions of Mercury

19 Jul 2136 – Evening apparition
02 Sep 2136 – Morning apparition
13 Nov 2136 – Evening apparition
22 Dec 2136 – Morning apparition
05 Mar 2137 – Evening apparition
19 Apr 2137 – Morning apparition
01 Jul 2137 – 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 16h10m40s 18°25'S Scorpius 7.3"
Sun 17h38m 23°19'S Ophiuchus 32'30"

The coordinates above are given in J2000.0.

The sky on 27 Nov 2024

The sky on 27 November 2024
Sunrise
06:52
Sunset
16:25
Twilight ends
18:03
Twilight begins
05:14


Waning Crescent

8%

26 days old

Planets
Rise Culm. Set
Mercury 08:19 12:49 17:19
Venus 10:16 14:45 19:15
Moon 03:23 08:52 14:13
Mars 20:35 03:58 11:22
Jupiter 17:04 00:31 07:58
Saturn 12:50 18:22 23:54
All times shown in EST.

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

18 Nov 2136  –  Mercury at highest altitude in evening sky
20 Dec 2136  –  Mercury at highest altitude in morning sky
22 Dec 2136  –  Mercury at greatest elongation west
06 Mar 2137  –  Mercury at highest altitude in evening sky

Image credit

© NASA/JPL/MESSENGER

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