© NASA/JPL/MESSENGER

Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

Objects: Mercury
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Mercury will reach half phase in its Jul–Aug 2006 morning apparition. It will be shining brightly at mag -0.4.

From Columbus , this apparition will be well placed but tricky to observe, reaching a peak altitude of 16° above the horizon at sunrise on 10 Aug 2006.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

Jul–Aug 2006 morning apparition of Mercury

18 Jul 2006 – Mercury at inferior solar conjunction
07 Aug 2006 – Mercury at greatest elongation west
09 Aug 2006 – Mercury at highest altitude in morning sky
09 Aug 2006 – Mercury at dichotomy
01 Sep 2006 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

23 Feb 2006 – Evening apparition
08 Apr 2006 – Morning apparition
20 Jun 2006 – Evening apparition
07 Aug 2006 – Morning apparition
16 Oct 2006 – Evening apparition
25 Nov 2006 – Morning apparition
07 Feb 2007 – 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 08h00m20s 19°43'N Cancer 7.0"
Sun 09h17m 15°45'N Cancer 31'33"

The coordinates above are given in J2000.0.

The sky on 22 Nov 2024

The sky on 22 November 2024
Sunrise
07:23
Sunset
17:10
Twilight ends
18:45
Twilight begins
05:47

21-day old moon
Waning Gibbous

52%

21 days old

Planets
Rise Culm. Set
Mercury 09:15 13:45 18:15
Venus 10:48 15:18 19:49
Moon 22:59 06:12 13:13
Mars 21:34 04:54 12:13
Jupiter 18:09 01:32 08:56
Saturn 13:47 19:20 00:53
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

09 Aug 2006  –  Mercury at highest altitude in morning sky
15 Oct 2006  –  Mercury at highest altitude in evening sky
16 Oct 2006  –  Mercury at greatest elongation east
08 Nov 2006  –  Transit of Mercury

Image credit

© NASA/JPL/MESSENGER

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Columbus

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39.96°N
83.00°W
EST

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