Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Apr–May 2176 morning apparition. It will be shining brightly at mag 0.2.

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 sunrise on 27 Apr 2176.

Apr–May 2176 morning apparition of Mercury

30 Mar 2176 – Mercury at inferior solar conjunction
26 Apr 2176 – Mercury at highest altitude in morning sky
27 Apr 2176 – Mercury at greatest elongation west
30 Apr 2176 – Mercury at dichotomy
04 Jun 2176 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

22 Nov 2175 – Evening apparition
31 Dec 2175 – Morning apparition
13 Mar 2176 – Evening apparition
27 Apr 2176 – Morning apparition
09 Jul 2176 – Evening apparition
24 Aug 2176 – Morning apparition
04 Nov 2176 – 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 00h48m50s 2°07'N Cetus 7.5"
Sun 02h26m 14°26'N Aries 31'46"

The coordinates above are given in J2000.0.

The sky on 18 May 2024

The sky on 18 May 2024
Sunrise
05:17
Sunset
20:02
Twilight ends
22:03
Twilight begins
03:16


Waxing Gibbous

82%

10 days old

Planets
Rise Culm. Set
Mercury 04:26 11:06 17:46
Venus 05:09 12:21 19:33
Moon 15:14 21:22 03:19
Mars 03:30 09:48 16:07
Jupiter 05:23 12:40 19:57
Saturn 02:36 08:15 13:54
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

27 Apr 2176  –  Mercury at greatest elongation west
02 Jul 2176  –  Mercury at highest altitude in evening sky
09 Jul 2176  –  Mercury at greatest elongation east
24 Aug 2176  –  Mercury at greatest elongation west

Image credit

© NASA/JPL/MESSENGER

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