Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Jan–Feb 2145 evening apparition. It will be shining brightly at mag -0.6.

From Cambridge , this apparition will be well placed but tricky to observe, reaching a peak altitude of 15° above the horizon at sunset on 12 Feb 2145.

Jan–Feb 2145 evening apparition of Mercury

09 Jan 2145 – Mercury at superior solar conjunction
10 Feb 2145 – Mercury at greatest elongation east
10 Feb 2145 – Mercury at dichotomy
11 Feb 2145 – Mercury at highest altitude in evening sky
25 Feb 2145 – Mercury at inferior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

09 Aug 2144 – Morning apparition
19 Oct 2144 – Evening apparition
28 Nov 2144 – Morning apparition
10 Feb 2145 – Evening apparition
24 Mar 2145 – Morning apparition
05 Jun 2145 – Evening apparition
23 Jul 2145 – 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 22h38m50s 7°39'S Aquarius 7.2"
Sun 21h30m 14°43'S Capricornus 32'25"

The coordinates above are given in J2000.0.

The sky on 21 Nov 2024

The sky on 21 November 2024
Sunrise
06:40
Sunset
16:16
Twilight ends
17:55
Twilight begins
05:01


Waning Gibbous

53%

20 days old

Planets
Rise Culm. Set
Mercury 08:38 12:59 17:20
Venus 10:08 14:29 18:51
Moon 20:55 04:36 12:04
Mars 20:43 04:09 11:36
Jupiter 17:18 00:49 08:20
Saturn 13:06 18:36 00:07
All times shown in EST.

Warning

Never attempt to point a pair of binoculars or a telescope at an object close to the Sun. Doing so may result in immediate and permanent blindness.

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

10 Feb 2145  –  Mercury at greatest elongation east
11 Feb 2145  –  Mercury at highest altitude in evening sky
16 Mar 2145  –  Mercury at highest altitude in morning sky
24 Mar 2145  –  Mercury at greatest elongation west

Image credit

© NASA/JPL/MESSENGER

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