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Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

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The sky at

Mercury will reach half phase in its 2014 evening apparition. It will be shining brightly at mag -0.6.

From Ashburn , this apparition will be well placed but tricky to observe, reaching a peak altitude of 16° above the horizon at sunset on 1 Feb 2014.

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

The table below lists how high Mercury will appear at sunset over the course of the apparition. All times are given in Ashburn local time.

Date Sun
sets at
Mercury
sets at
Altitude
at sunset
Direction
at sunset
11 Jan 201417:0617:39south-west
14 Jan 201417:0917:53south-west
17 Jan 201417:1218:07south-west
20 Jan 201417:1518:2111°south-west
23 Jan 201417:1918:3513°south-west
26 Jan 201417:2218:4715°south-west
29 Jan 201417:2618:5616°south-west
01 Feb 201417:2919:0116°south-west
04 Feb 201417:3319:0016°south-west
07 Feb 201417:3618:5113°south-west
10 Feb 201417:4018:3410°west

A graph of the phase of Mercury is available here.

Observing Mercury

The 2014 evening apparition of Mercury
29 Dec 2013 – Mercury at superior solar conjunction
31 Jan 2014 – Mercury at greatest elongation east
01 Feb 2014 – Mercury at dichotomy
03 Feb 2014 – Mercury reaches highest point in evening sky

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 days 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 hours, 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 22h09m20s -10°50' Aquarius 7.2"
Sun 20h58m -17°09' Capricornus 32'27"

The coordinates above are given in J2000.0.

The sky on 01 February 2014
Sunrise
07:15
Sunset
17:29
Twilight ends
19:01
Twilight begins
05:44

2-day old moon
Waxing Crescent

2%

2 days old

Planets
Rise Culm. Set
Mercury 08:05 13:33 19:01
Venus 05:08 10:18 15:27
Moon 08:11 13:59 19:47
Mars 23:08 04:52 10:34
Jupiter 14:48 22:12 05:41
Saturn 01:37 06:45 11:54
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 DE405 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

31 Jan 2014  –  Mercury at greatest elongation east
03 Feb 2014  –  Mercury reaches highest point in evening sky
04 Mar 2014  –  Mercury reaches highest point in morning sky
14 Mar 2014  –  Mercury at greatest elongation west

Image credit

None available.

Ashburn

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Longitude:
Timezone:

39.04°N
77.49°W
EST

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