© NASA/JPL/MESSENGER

Mercury at aphelion

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

Object Right Ascension Declination Constellation Angular Size
Mercury 01h33m40s +07°11' Pisces 10.2"
Sun 02h54m +16°37' Aries 31'42"

The coordinates above are given in J2000.0.

From Cambridge, Mercury will not be observable – it will reach its highest point in the sky during daytime and will be 2° below the horizon at dawn.

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 06 May 2017
Sunrise
05:31
Sunset
19:48
Twilight ends
21:40
Twilight begins
03:39

10-day old moon
Waxing Gibbous

82%

10 days old

Planets
Rise Culm. Set
Mercury 04:50 11:19 17:49
Venus 03:50 10:00 16:10
Moon 15:53 22:01 03:40
Mars 06:46 14:19 21:52
Jupiter 16:52 22:40 04:31
Saturn 22:52 03:33 08:10
All times shown in EDT.

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

03 Apr 2017  –  Mercury reaches highest point in evening sky
17 May 2017  –  Mercury at greatest elongation west
25 May 2017  –  Mercury reaches highest point in morning sky
16 Jul 2017  –  Mercury reaches highest point in evening sky

Image credit

© NASA/JPL/MESSENGER

Cambridge

Latitude:
Longitude:
Timezone:

42.38°N
71.11°W
EDT

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