© NASA/JPL/MESSENGER

Mercury at perihelion

Dominic Ford, Editor
From the Inner Planets feed

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The sky at

Mercury's 88-day orbit around the Sun will carry it to its closest point to the Sun – its perihelion – at a distance of 0.31 AU from the Sun.

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 perihelion will be:

Object Right Ascension Declination Constellation Angular Size
Mercury 09h25m30s +16°07' Leo 6.0"
Sun 10h24m +09°59' Leo 31'39"

The coordinates above are given in J2000.0.

From Cambridge, Mercury will be difficult to observe as it will appear no higher than 9° above the horizon. It will be visible in the dawn sky, rising at 04:41 (EDT) – 1 hour and 22 minutes before the Sun – and reaching an altitude of 9° above the eastern horizon before fading from view as dawn breaks around 05:44.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.
The sky on 27 August 2025
Sunrise
06:02
Sunset
19:25
Twilight ends
21:07
Twilight begins
04:21

4-day old moon
Waxing Crescent

17%

4 days old

Planets
Rise Culm. Set
Mercury 04:42 11:46 18:50
Venus 03:17 10:36 17:56
Moon 10:39 15:53 21:08
Mars 09:21 15:07 20:52
Jupiter 02:00 09:32 17:04
Saturn 20:26 02:25 08:20
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 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

19 Aug 2025  –  Mercury reaches highest point in morning sky
29 Oct 2025  –  Mercury at greatest elongation east
01 Nov 2025  –  Mercury reaches highest point in evening sky
08 Dec 2025  –  Mercury reaches highest point in morning sky

Image credit

© NASA/JPL/MESSENGER

Cambridge

Latitude:
Longitude:
Timezone:

42.38°N
71.11°W
EDT

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