© NASA/JPL/MESSENGER

Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

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Mercury will reach half phase in its 2016 morning apparition. It will be shining brightly at mag -0.0.

From Ashburn , this apparition will not be one of the most prominent and very difficult to observe, reaching a peak altitude of 12° above the horizon at sunrise on 11 Jun 2016.

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 sunrise over the course of the apparition. All times are given in Ashburn local time.

Date Sun
sets at
Mercury
rises at
Altitude
at sunrise
Direction
at sunrise
21 May 201605:5305:14north-west
24 May 201605:5105:05north-west
27 May 201605:4904:56north-west
30 May 201605:4804:4910°north-west
02 Jun 201605:4704:4311°north-west
05 Jun 201605:4604:3911°north-west
08 Jun 201605:4504:3512°north-west
11 Jun 201605:4504:3412°north-west
14 Jun 201605:4504:3312°north-west
17 Jun 201605:4504:3511°north-west
20 Jun 201605:4604:3910°north-west
23 Jun 201605:4604:45north-west
26 Jun 201605:4704:54north-west
29 Jun 201605:4905:06north-west

A graph of the phase of Mercury is available here.

Observing Mercury

The 2016 morning apparition of Mercury
05 Jun 2016 – Mercury at greatest elongation west
11 Jun 2016 – Mercury at dichotomy
13 Jun 2016 – Mercury reaches highest point in morning 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 03h44m30s +16°46' Taurus 7.2"
Sun 05h19m +23°06' Taurus 31'30"

The coordinates above are given in J2000.0.

The sky on 11 June 2016
Sunrise
05:42
Sunset
20:34
Twilight ends
22:33
Twilight begins
03:44

6-day old moon
Waxing Crescent

40%

6 days old

Planets
Rise Culm. Set
Mercury 04:34 11:34 18:34
Venus 05:48 13:14 20:39
Moon 12:37 18:58 00:46
Mars 18:24 23:14 04:10
Jupiter 12:26 18:52 01:22
Saturn 19:37 00:34 05:27
All times shown in EDT.

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

05 Jun 2016  –  Mercury at greatest elongation west
13 Jun 2016  –  Mercury reaches highest point in morning sky
03 Aug 2016  –  Mercury reaches highest point in evening sky
16 Aug 2016  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

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