© 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 Aug–Sep 2050 morning apparition. It will be shining brightly at mag -0.5.

From Cambridge , this apparition will be well placed but tricky to observe, reaching a peak altitude of 16° above the horizon at sunrise on 12 Sep 2050.

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Aug–Sep 2050 morning apparition of Mercury

24 Aug 2050 – Mercury at inferior solar conjunction
10 Sep 2050 – Mercury at greatest elongation west
11 Sep 2050 – Mercury at dichotomy
11 Sep 2050 – Mercury at highest altitude in morning sky
06 Oct 2050 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

30 Mar 2050 – Evening apparition
15 May 2050 – Morning apparition
28 Jul 2050 – Evening apparition
10 Sep 2050 – Morning apparition
22 Nov 2050 – Evening apparition
31 Dec 2050 – Morning apparition
13 Mar 2051 – 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 10h10m50s 11°45'N Leo 7.0"
Sun 11h17m 4°35'N Leo 31'46"

The coordinates above are given in J2000.0.

The sky on 20 May 2024

The sky on 20 May 2024
Sunrise
05:15
Sunset
20:04
Twilight ends
22:06
Twilight begins
03:13

12-day old moon
Waxing Gibbous

94%

12 days old

Planets
Rise Culm. Set
Mercury 04:25 11:09 17:52
Venus 05:08 12:23 19:38
Moon 17:19 22:43 03:57
Mars 03:26 09:46 16:07
Jupiter 05:17 12:34 19:51
Saturn 02:28 08:07 13:47
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

10 Sep 2050  –  Mercury at greatest elongation west
11 Sep 2050  –  Mercury at highest altitude in morning sky
22 Nov 2050  –  Mercury at greatest elongation east
26 Nov 2050  –  Mercury at highest altitude in evening sky

Image credit

© NASA/JPL/MESSENGER

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Cambridge

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42.38°N
71.11°W
EDT

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