Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Aug–Sep 1992 morning apparition. It will be shining brightly at mag -0.4.

From Los Angeles , this apparition will be well placed but tricky to observe, reaching a peak altitude of 17° above the horizon at sunrise on 23 Aug 1992.

Aug–Sep 1992 morning apparition of Mercury

02 Aug 1992 – Mercury at inferior solar conjunction
20 Aug 1992 – Mercury at greatest elongation west
21 Aug 1992 – Mercury at highest altitude in morning sky
22 Aug 1992 – Mercury at dichotomy
14 Sep 1992 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

09 Mar 1992 – Evening apparition
23 Apr 1992 – Morning apparition
05 Jul 1992 – Evening apparition
20 Aug 1992 – Morning apparition
31 Oct 1992 – Evening apparition
09 Dec 1992 – Morning apparition
20 Feb 1993 – 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 08h57m00s 16°58'N Cancer 7.0"
Sun 10h09m 11°24'N Leo 31'38"

The coordinates above are given in J2000.0.

The sky on 28 Apr 2024

The sky on 28 April 2024
Sunrise
06:04
Sunset
19:34
Twilight ends
21:06
Twilight begins
04:32


Waning Gibbous

74%

20 days old

Planets
Rise Culm. Set
Mercury 05:11 11:26 17:41
Venus 05:43 12:12 18:42
Moon 23:42 04:27 09:12
Mars 04:22 10:19 16:17
Jupiter 06:54 13:48 20:41
Saturn 03:52 09:35 15:19
All times shown in PDT.

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

22 Aug 1992  –  Mercury at highest altitude in morning sky
31 Oct 1992  –  Mercury at greatest elongation east
02 Nov 1992  –  Mercury at highest altitude in evening sky
08 Dec 1992  –  Mercury at highest altitude in morning sky

Image credit

© NASA/JPL/MESSENGER

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