© 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 Oct–Nov 2073 morning apparition. It will be shining brightly at mag -0.5.

From Jacksonville , this apparition will not be one of the most prominent and tricky to observe, reaching a peak altitude of 18° above the horizon at sunrise on 5 Nov 2073.

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Oct–Nov 2073 morning apparition of Mercury

19 Oct 2073 – Mercury at inferior solar conjunction
02 Nov 2073 – Mercury at dichotomy
04 Nov 2073 – Mercury at highest altitude in morning sky
04 Nov 2073 – Mercury at greatest elongation west
12 Dec 2073 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

28 May 2073 – Evening apparition
16 Jul 2073 – Morning apparition
24 Sep 2073 – Evening apparition
04 Nov 2073 – Morning apparition
17 Jan 2074 – Evening apparition
27 Feb 2074 – Morning apparition
10 May 2074 – 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 13h22m30s 6°25'S Virgo 7.2"
Sun 14h30m 14°48'S Libra 32'14"

The coordinates above are given in J2000.0.

The sky on 15 Jun 2024

The sky on 15 June 2024
Sunrise
06:21
Sunset
20:29
Twilight ends
22:07
Twilight begins
04:44

9-day old moon
Waxing Gibbous

71%

9 days old

Planets
Rise Culm. Set
Mercury 06:25 13:30 20:35
Venus 06:35 13:38 20:41
Moon 14:41 20:41 02:33
Mars 03:28 09:59 16:30
Jupiter 05:06 11:59 18:52
Saturn 01:23 07:11 13:00
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

24 Sep 2073  –  Mercury at greatest elongation east
04 Nov 2073  –  Mercury at highest altitude in morning sky
04 Nov 2073  –  Mercury at greatest elongation west
17 Jan 2074  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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