Mercury at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

Mercury will reach half phase in its Nov–Dec 2000 morning apparition. It will be shining brightly at mag -0.5.

From Cambridge , this apparition will be exceptionally well placed but tricky to observe, reaching a peak altitude of 17° above the horizon at sunrise on 15 Nov 2000.

Nov–Dec 2000 morning apparition of Mercury

29 Oct 2000 – Mercury at inferior solar conjunction
12 Nov 2000 – Mercury at dichotomy
14 Nov 2000 – Mercury at highest altitude in morning sky
15 Nov 2000 – Mercury at greatest elongation west
25 Dec 2000 – Mercury at superior solar conjunction

A graph of the phase of Mercury is available here.

Apparitions of Mercury

09 Jun 2000 – Evening apparition
27 Jul 2000 – Morning apparition
06 Oct 2000 – Evening apparition
15 Nov 2000 – Morning apparition
28 Jan 2001 – Evening apparition
10 Mar 2001 – Morning apparition
22 May 2001 – 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 14h02m00s 9°56'S Virgo 7.2"
Sun 15h13m 17°57'S Libra 32'19"

The coordinates above are given in J2000.0.

The sky on 30 Apr 2024

The sky on 30 April 2024
Sunrise
05:38
Sunset
19:42
Twilight ends
21:32
Twilight begins
03:49


Waning Gibbous

52%

22 days old

Planets
Rise Culm. Set
Mercury 04:53 11:13 17:32
Venus 05:22 12:05 18:48
Moon 01:45 06:07 10:35
Mars 04:10 10:09 16:07
Jupiter 06:21 13:33 20:46
Saturn 03:43 09:20 14:58
All times shown in EDT.

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

06 Oct 2000  –  Mercury at greatest elongation east
14 Nov 2000  –  Mercury at highest altitude in morning sky
15 Nov 2000  –  Mercury at greatest elongation west
28 Jan 2001  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

Share