Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Feb–Apr 2034 morning apparition. It will be shining brightly at mag 0.1.

From Fairfield , this apparition will not be one of the most prominent and very difficult to observe, reaching a peak altitude of 11° above the horizon at sunrise on 27 Feb 2034.

Feb–Apr 2034 morning apparition of Mercury

11 Feb 2034 – Mercury at inferior solar conjunction
01 Mar 2034 – Mercury at highest altitude in morning sky
05 Mar 2034 – Mercury at dichotomy
09 Mar 2034 – Mercury at greatest elongation west
21 Apr 2034 – Mercury at superior solar conjunction

The table below lists the altitude of Mercury at sunrise over the course of the apparition. All times are given in Fairfield local time.

Date Sun
rises at
Mercury
rises at
Altitude
at sunrise
Direction
at sunrise
Mag Phase
15 Feb 203406:4506:06east3.55%
18 Feb 203406:4105:49south-east2.112%
21 Feb 203406:3705:3510°south-east1.320%
24 Feb 203406:3205:2511°south-east0.728%
27 Feb 203406:2805:1811°south-east0.436%
02 Mar 203406:2305:1311°south-east0.343%
05 Mar 203406:1805:1011°south-east0.249%
08 Mar 203406:1305:0810°south-east0.154%
11 Mar 203406:0905:0710°south-east0.159%
14 Mar 203407:0406:06south-east0.063%
17 Mar 203406:5906:05south-east-0.067%
20 Mar 203406:5406:05south-east-0.070%
23 Mar 203406:4906:04east-0.173%
26 Mar 203406:4406:04east-0.277%
29 Mar 203406:3906:03east-0.280%
01 Apr 203406:3406:02east-0.383%

Mercury will brighten rapidly at the start of its morning apparition as it emerges from inferior conjunction. Prior to its apparition, it passed between the Earth and Sun, at which time it had its unilluminated side turned towards the Earth and so appeared as a thin, barely illuminated crescent. As the apparition proceeds, this crescent waxes and becomes gibbous.

Since Mercury can only ever be observed in twilight, it is particularly difficult to find when it is in a thin crescent phase. Thus, it will be significantly easier to see in the days after it reaches its highest point in the sky – when it will show a gibbous phase – than in the days beforehand.

A graph of the phase of Mercury is available here.

Apparitions of Mercury

04 Oct 2033 – Evening apparition
13 Nov 2033 – Morning apparition
26 Jan 2034 – Evening apparition
09 Mar 2034 – Morning apparition
20 May 2034 – Evening apparition
08 Jul 2034 – Morning apparition
16 Sep 2034 – 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 21h20m50s 15°27'S Capricornus 7.6"
Sun 23h04m 5°57'S Aquarius 32'15"

The coordinates above are given in J2000.0.

The sky on 5 Mar 2034

The sky on 5 March 2034
Sunrise
06:18
Sunset
17:47
Twilight ends
19:18
Twilight begins
04:47


Waning Gibbous

98%

15 days old

Planets
Rise Culm. Set
Mercury 05:12 10:19 15:26
Venus 07:00 12:58 18:56
Moon 17:39 00:05 06:23
Mars 08:20 15:13 22:07
Jupiter 06:34 12:18 18:01
Saturn 12:29 19:58 03:26
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

01 Mar 2034  –  Mercury at highest altitude in morning sky
09 Mar 2034  –  Mercury at greatest elongation west
18 May 2034  –  Mercury at highest altitude in evening sky
20 May 2034  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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