Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Apr–May 2048 evening apparition. It will be shining brightly at mag -0.3.

From Fairfield , this apparition will be exceptionally well placed but tricky to observe, reaching a peak altitude of 18° above the horizon at sunset on 4 May 2048.

Apr–May 2048 evening apparition of Mercury

07 Apr 2048 – Mercury at superior solar conjunction
29 Apr 2048 – Mercury at dichotomy
03 May 2048 – Mercury at highest altitude in evening sky
04 May 2048 – Mercury at greatest elongation east
27 May 2048 – Mercury at inferior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

30 Oct 2047 – Morning apparition
13 Jan 2048 – Evening apparition
22 Feb 2048 – Morning apparition
04 May 2048 – Evening apparition
21 Jun 2048 – Morning apparition
01 Sep 2048 – Evening apparition
13 Oct 2048 – 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 03h48m40s 22°36'N Taurus 7.1"
Sun 02h29m 14°45'N Aries 31'45"

The coordinates above are given in J2000.0.

The sky on 25 Nov 2024

The sky on 25 November 2024
Sunrise
06:50
Sunset
16:26
Twilight ends
18:04
Twilight begins
05:13


Waning Crescent

23%

24 days old

Planets
Rise Culm. Set
Mercury 08:30 12:58 17:26
Venus 10:15 14:43 19:11
Moon 01:23 07:34 13:35
Mars 20:42 04:05 11:28
Jupiter 17:13 00:40 08:07
Saturn 12:57 18:29 00:01
All times shown in EST.

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

22 Feb 2048  –  Mercury at greatest elongation west
03 May 2048  –  Mercury at highest altitude in evening sky
04 May 2048  –  Mercury at greatest elongation east
21 Jun 2048  –  Mercury at greatest elongation west

Image credit

© NASA/JPL/MESSENGER

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