© 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 09h05m40s 14°12'N Cancer 9.8"
Sun 07h34m 21°38'N Gemini 31'28"

The coordinates above are given in J2000.0.

From Ashburn, Mercury will not be observable – it will reach its highest point in the sky during daytime and will be no higher than 1° above the horizon at dusk.

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The sky on 14 Jul 2025

The sky on 14 July 2025
Sunrise
05:53
Sunset
20:35
Twilight ends
22:29
Twilight begins
03:58

19-day old moon
Waning Gibbous

81%

19 days old

Planets
Rise Culm. Set
Mercury 07:53 14:44 21:34
Venus 03:06 10:17 17:28
Moon 22:37 04:06 09:45
Mars 10:21 16:45 23:09
Jupiter 04:47 12:11 19:36
Saturn 23:51 05:49 11:47
All times shown in EDT.

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

04 Jul 2025  –  Mercury at greatest elongation east
19 Aug 2025  –  Mercury at greatest elongation west
21 Aug 2025  –  Mercury at highest altitude in morning sky
29 Oct 2025  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

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Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

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