© NASA/JPL/MESSENGER

Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

Objects: Mercury
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Mercury will reach half phase in its Jan–Feb 2293 morning apparition. It will be shining brightly at mag -0.1.

From Fairfield , this apparition will not be one of the most prominent and tricky to observe, reaching a peak altitude of 14° above the horizon at sunrise on 21 Jan 2293.

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Jan–Feb 2293 morning apparition of Mercury

03 Jan 2293 – Mercury at inferior solar conjunction
20 Jan 2293 – Mercury at dichotomy
20 Jan 2293 – Mercury at highest altitude in morning sky
25 Jan 2293 – Mercury at greatest elongation west

A graph of the phase of Mercury is available here.

Apparitions of Mercury

22 Aug 2292 – Evening apparition
04 Oct 2292 – Morning apparition
17 Dec 2292 – Evening apparition
25 Jan 2293 – Morning apparition
07 Apr 2293 – Evening apparition
24 May 2293 – Morning apparition
05 Aug 2293 – 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 18h12m50s 21°13'S Sagittarius 7.5"
Sun 19h53m 20°51'S Sagittarius 32'30"

The coordinates above are given in J2000.0.

The sky on 24 Nov 2024

The sky on 24 November 2024
Sunrise
06:49
Sunset
16:27
Twilight ends
18:04
Twilight begins
05:12

23-day old moon
Waning Crescent

28%

23 days old

Planets
Rise Culm. Set
Mercury 08:34 13:01 17:28
Venus 10:14 14:42 19:09
Moon 00:22 06:55 13:17
Mars 20:46 04:08 11:31
Jupiter 17:18 00:45 08:11
Saturn 13:01 18:33 00:05
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

21 Dec 2292  –  Mercury at highest altitude in evening sky
20 Jan 2293  –  Mercury at highest altitude in morning sky
25 Jan 2293  –  Mercury at greatest elongation west
07 Apr 2293  –  Mercury at highest altitude in evening sky

Image credit

© NASA/JPL/MESSENGER

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