Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Aug–Sep 2297 evening apparition. It will be shining brightly at mag 0.1.

From Cambridge , this apparition will not be one of the most prominent and very difficult to observe, reaching a peak altitude of 8° above the horizon at sunset on 7 Sep 2297.

Aug–Sep 2297 evening apparition of Mercury

07 Aug 2297 – Mercury at superior solar conjunction
09 Sep 2297 – Mercury at highest altitude in evening sky
20 Sep 2297 – Mercury at greatest elongation east
24 Sep 2297 – Mercury at dichotomy
15 Oct 2297 – Mercury at inferior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

12 Mar 2297 – Morning apparition
23 May 2297 – Evening apparition
11 Jul 2297 – Morning apparition
20 Sep 2297 – Evening apparition
31 Oct 2297 – Morning apparition
13 Jan 2298 – Evening apparition
23 Feb 2298 – Morning 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 13h24m00s 12°14'S Virgo 7.5"
Sun 11h52m 0°49'N Virgo 31'50"

The coordinates above are given in J2000.0.

The sky on 3 Jul 2024

The sky on 3 July 2024
Sunrise
05:09
Sunset
20:24
Twilight ends
22:37
Twilight begins
02:56


Waning Crescent

4%

27 days old

Planets
Rise Culm. Set
Mercury 06:44 14:12 21:39
Venus 05:47 13:21 20:56
Moon 02:34 10:37 18:50
Mars 01:52 08:57 16:02
Jupiter 02:57 10:23 17:48
Saturn 23:39 05:19 11:00
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

20 Sep 2297  –  Mercury at greatest elongation east
31 Oct 2297  –  Mercury at highest altitude in morning sky
31 Oct 2297  –  Mercury at greatest elongation west
13 Jan 2298  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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