Mercury will reach half phase in its Jul–Aug 2029 evening apparition. It will be shining brightly at mag 0.2.
From Cambridge , this apparition will not be one of the most prominent and very difficult to observe, reaching a peak altitude of 10° above the horizon at sunset on 8 Aug 2029.
Jul–Aug 2029 evening apparition of Mercury
09 Jul 2029 | – | Mercury at superior solar conjunction |
07 Aug 2029 | – | Mercury at highest altitude in evening sky |
19 Aug 2029 | – | Mercury at greatest elongation east |
20 Aug 2029 | – | Mercury at dichotomy |
15 Sep 2029 | – | Mercury at inferior solar conjunction |
The table below lists the altitude of Mercury at sunset over the course of the apparition. All times are given in Cambridge local time.
Date | Sun sets at |
Mercury sets at |
Altitude at sunset |
Direction at sunset |
Mag | Phase |
18 Jul 2029 | 20:16 | 20:52 | 5° | north-west | -1.2 | 94% |
21 Jul 2029 | 20:14 | 20:57 | 7° | west | -0.9 | 90% |
24 Jul 2029 | 20:11 | 21:00 | 8° | west | -0.7 | 86% |
27 Jul 2029 | 20:08 | 21:01 | 9° | west | -0.5 | 82% |
30 Jul 2029 | 20:05 | 21:01 | 9° | west | -0.3 | 79% |
02 Aug 2029 | 20:02 | 20:59 | 10° | west | -0.2 | 75% |
05 Aug 2029 | 19:58 | 20:56 | 10° | west | -0.1 | 71% |
08 Aug 2029 | 19:54 | 20:52 | 10° | west | -0.0 | 67% |
11 Aug 2029 | 19:50 | 20:47 | 10° | west | 0.0 | 64% |
14 Aug 2029 | 19:46 | 20:41 | 9° | west | 0.1 | 60% |
17 Aug 2029 | 19:42 | 20:34 | 9° | west | 0.2 | 56% |
20 Aug 2029 | 19:37 | 20:27 | 8° | west | 0.2 | 51% |
23 Aug 2029 | 19:32 | 20:18 | 8° | west | 0.3 | 46% |
26 Aug 2029 | 19:27 | 20:09 | 7° | west | 0.4 | 41% |
29 Aug 2029 | 19:22 | 19:58 | 6° | west | 0.6 | 35% |
Mercury will fade rapidly towards the end of the apparition as it heads towards inferior conjunction, when it will pass between the Earth and Sun. At inferior conjunction, the planet turns its unilluminated side towards the Earth, and so appears as a thin, barely illuminated crescent.
Since Mercury can only ever be observed in twilight, it is particularly difficult to find when it is in a thin crescent phase. Thus, it will be significantly easier to see in the days before it reaches its highest point in the sky than in the days after.
Altitude of Mercury at sunset
A graph of the phase of Mercury is available here.
Apparitions of Mercury
08 Feb 2029 | – | Morning apparition |
21 Apr 2029 | – | Evening apparition |
08 Jun 2029 | – | Morning apparition |
19 Aug 2029 | – | Evening apparition |
01 Oct 2029 | – | Morning apparition |
14 Dec 2029 | – | Evening apparition |
22 Jan 2030 | – | Morning 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 | 11h38m10s | 0°01'S | Virgo | 7.5" |
Sun | 09h59m | 12°16'N | Leo | 31'37" |
The coordinates above are given in J2000.0.
The sky on 20 Aug 2029
The sky on 20 August 2029 | ||||||||||||||||||||||||||||||||||
92% 10 days old |
All times shown in EDT.
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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
19 Aug 2029 | – Mercury at greatest elongation east |
01 Oct 2029 | – Mercury at greatest elongation west |
02 Oct 2029 | – Mercury at highest altitude in morning sky |
14 Dec 2029 | – Mercury at greatest elongation east |
Image credit
© NASA/JPL/MESSENGER