© 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 Jul–Aug 2152 morning apparition. It will be shining brightly at mag -0.3.

From Ashburn , this apparition will not be one of the most prominent and tricky to observe, reaching a peak altitude of 15° above the horizon at sunrise on 20 Jul 2152.

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Jul–Aug 2152 morning apparition of Mercury

22 Jun 2152 – Mercury at inferior solar conjunction
15 Jul 2152 – Mercury at greatest elongation west
19 Jul 2152 – Mercury at highest altitude in morning sky
19 Jul 2152 – Mercury at dichotomy
11 Aug 2152 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

03 Feb 2152 – Evening apparition
16 Mar 2152 – Morning apparition
28 May 2152 – Evening apparition
15 Jul 2152 – Morning apparition
24 Sep 2152 – Evening apparition
03 Nov 2152 – Morning apparition
17 Jan 2153 – 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 06h23m50s 21°33'N Gemini 7.0"
Sun 07h50m 21°00'N Gemini 31'28"

The coordinates above are given in J2000.0.

The sky on 28 Mar 2024

The sky on 28 March 2024
Sunrise
06:58
Sunset
19:29
Twilight ends
21:00
Twilight begins
05:27

18-day old moon
Waning Gibbous

87%

18 days old

Planets
Rise Culm. Set
Mercury 07:29 14:14 20:59
Venus 06:24 12:10 17:56
Moon 22:00 03:15 08:23
Mars 05:43 11:09 16:35
Jupiter 08:42 15:39 22:36
Saturn 06:07 11:43 17:19
All times shown in EDT.

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

19 Jul 2152  –  Mercury at highest altitude in morning sky
14 Sep 2152  –  Mercury at highest altitude in evening sky
24 Sep 2152  –  Mercury at greatest elongation east
04 Nov 2152  –  Mercury at highest altitude in morning sky

Image credit

© NASA/JPL/MESSENGER

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