© NASA/JPL/MESSENGER

Mercury at aphelion

Dominic Ford, Editor
From the Inner Planets feed

Objects: Mercury
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The sky at

Mercury's 88-day orbit around the Sun will carry it to its furthest point to the Sun – its aphelion – at a distance of 0.47 AU.

Unlike most of the planets, which follow almost exactly circular orbits around the Sun only varying in their distance from the Sun by a few percent, Mercury has a significantly elliptical orbit.

Its distance from the Sun varies between 0.307 AU at perihelion (closest approach to the Sun), and 0.467 AU at aphelion (furthest recess from the Sun). This variation, of over 50%, means that its surface receives over twice as much energy from the Sun at perihelion as compared to aphelion.

However, this makes little difference to Mercury's telescopic appearance, since little if any detail on its surface can be resolved by ground-based telescopes. Although its changing seasons have an incredible effect upon its surface temperatures, there is little change that is visible to amateur observers.

The position of Mercury at the moment it passes aphelion will be:

Object Right Ascension Declination Constellation Angular Size
Mercury 16h44m50s 23°25'S Ophiuchus 4.6"
Sun 16h36m 22°02'S Ophiuchus 32'26"

The coordinates above are given in J2000.0.

From Ashburn, Mercury will not be readily observable since it will be very close to the Sun, at a separation of only 2° from it.

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The sky on 2 Dec 2021

The sky on 2 December 2021
Sunrise
07:08
Sunset
16:47
Twilight ends
18:22
Twilight begins
05:33

28-day old moon
Waning Crescent

1%

28 days old

Planets
Rise Culm. Set
Mercury 07:24 12:05 16:47
Venus 10:19 14:55 19:32
Moon 04:55 10:20 15:36
Mars 05:41 10:42 15:44
Jupiter 11:57 17:13 22:30
Saturn 11:09 16:08 21:07
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 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

24 Oct 2021  –  Mercury at greatest elongation west
07 Jan 2022  –  Mercury at greatest elongation east
09 Jan 2022  –  Mercury at highest altitude in evening sky
09 Feb 2022  –  Mercury at highest altitude in morning sky

Image credit

© NASA/JPL/MESSENGER

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Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

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