© NASA/JPL/MESSENGER

Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

Please wait
Loading 0/4
Click and drag to rotate
Mouse wheel to zoom in/out
Touch with mouse to dismiss
The sky at

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 tricky to observe, reaching a peak altitude of 14° above the horizon at sunrise on 30 Jan 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
18 Jan 201607:2806:46west
21 Jan 201607:2706:2410°west
24 Jan 201607:2506:0712°west
27 Jan 201607:2305:5613°west
30 Jan 201607:2005:4914°west
02 Feb 201607:1805:4613°west
05 Feb 201607:1505:4613°west
08 Feb 201607:1205:4713°west
11 Feb 201607:0905:4912°west
14 Feb 201607:0505:5111°west
17 Feb 201607:0205:5410°west
20 Feb 201606:5805:57west
23 Feb 201606:5406:00west
26 Feb 201606:5006:02west
29 Feb 201606:4506:04west
03 Mar 201606:4106:06west

A graph of the phase of Mercury is available here.

Observing Mercury

The 2016 morning apparition of Mercury
14 Jan 2016 – Mercury at inferior solar conjunction
31 Jan 2016 – Mercury reaches highest point in morning sky
01 Feb 2016 – Mercury at dichotomy
06 Feb 2016 – Mercury at greatest elongation west

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 19h13m20s -20°40' Sagittarius 7.5"
Sun 20h57m -17°14' Capricornus 32'27"

The coordinates above are given in J2000.0.

The sky on 01 February 2016
Sunrise
07:16
Sunset
17:28
Twilight ends
19:00
Twilight begins
05:44

22-day old moon
Waning Crescent

46%

22 days old

Planets
Rise Culm. Set
Mercury 05:46 10:38 15:30
Venus 05:25 10:10 14:56
Moon 00:59 06:21 11:44
Mars 01:04 06:17 11:30
Jupiter 20:37 02:59 09:16
Saturn 03:24 08:16 13:07
All times shown in EST.

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

01 Feb 2016  –  Mercury reaches highest point in morning sky
06 Feb 2016  –  Mercury at greatest elongation west
18 Apr 2016  –  Mercury at greatest elongation east
19 Apr 2016  –  Mercury reaches highest point in evening sky

Image credit

© NASA/JPL/MESSENGER

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EST

Color scheme