Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Feb–Mar 2160 morning apparition. It will be shining brightly at mag 0.0.

From Cambridge , this apparition will not be one of the most prominent and very difficult to observe, reaching a peak altitude of 12° above the horizon at sunrise on 13 Feb 2160.

Feb–Mar 2160 morning apparition of Mercury

26 Jan 2160 – Mercury at inferior solar conjunction
12 Feb 2160 – Mercury at highest altitude in morning sky
15 Feb 2160 – Mercury at dichotomy
20 Feb 2160 – Mercury at greatest elongation west

A graph of the phase of Mercury is available here.

Apparitions of Mercury

17 Sep 2159 – Evening apparition
28 Oct 2159 – Morning apparition
10 Jan 2160 – Evening apparition
20 Feb 2160 – Morning apparition
01 May 2160 – Evening apparition
19 Jun 2160 – Morning apparition
29 Aug 2160 – 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 20h00m40s 19°21'S Sagittarius 7.6"
Sun 21h45m 13°30'S Capricornus 32'24"

The coordinates above are given in J2000.0.

The sky on 27 Nov 2024

The sky on 27 November 2024
Sunrise
06:47
Sunset
16:13
Twilight ends
17:53
Twilight begins
05:07


Waning Crescent

9%

26 days old

Planets
Rise Culm. Set
Mercury 08:15 12:41 17:06
Venus 10:12 14:37 19:02
Moon 03:16 08:44 14:02
Mars 20:23 03:50 11:17
Jupiter 16:52 00:22 07:53
Saturn 12:42 18:13 23:44
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

12 Feb 2160  –  Mercury at highest altitude in morning sky
20 Feb 2160  –  Mercury at greatest elongation west
01 May 2160  –  Mercury at highest altitude in evening sky
01 May 2160  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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