© 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 13h48m20s -12°31' Virgo 5.4"
Sun 12h34m -03°45' Virgo 31'57"

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 3° above the horizon at dusk.

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 03 October 2019
Sunrise
07:06
Sunset
18:49
Twilight ends
20:18
Twilight begins
05:37

5-day old moon
Waxing Crescent

25%

5 days old

Planets
Rise Culm. Set
Mercury 08:51 14:12 19:32
Venus 08:14 13:49 19:25
Moon 12:41 17:32 22:23
Mars 06:14 12:20 18:27
Jupiter 12:45 17:30 22:14
Saturn 14:35 19:20 00:08
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

12 Aug 2019  –  Mercury reaches highest point in morning sky
17 Oct 2019  –  Mercury reaches highest point in evening sky
19 Oct 2019  –  Mercury at greatest elongation east
11 Nov 2019  –  Transit of Mercury

Image credit

© NASA/JPL/MESSENGER

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

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