© NASA/JPL/MESSENGER

Mercury at aphelion

Dominic Ford, Editor
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Ashburn
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 14h26m20s -15°45' Libra 5.1"
Sun 13h23m -08°49' Virgo 32'05"

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 2° 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 16 October 2018
Sunrise
07:19
Sunset
18:29
Twilight ends
19:58
Twilight begins
05:50

7-day old moon
Waxing Crescent

46%

7 days old

Planets
Rise Culm. Set
Mercury 08:47 13:57 19:07
Venus 08:52 13:42 18:32
Moon 14:25 19:18 00:10
Mars 15:37 20:33 01:29
Jupiter 09:58 14:59 20:00
Saturn 13:00 17:44 22:27
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

26 Aug 2018, 17:48 EDT  –  Mercury at greatest elongation west
06 Nov 2018, 09:59 EST  –  Mercury at greatest elongation east
15 Dec 2018, 10:17 EST  –  Mercury at greatest elongation west
26 Feb 2019, 16:29 EST  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

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