© 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 10h32m00s +07°07' Leo 8.2"
Sun 08h50m +17°41' Cancer 31'31"

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 4° above the horizon at dusk.

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The sky on 02 August 2017
Sunrise
06:10
Sunset
20:19
Twilight ends
22:05
Twilight begins
04:25

10-day old moon
Waxing Gibbous

76%

10 days old

Planets
Rise Culm. Set
Mercury 08:30 14:56 21:22
Venus 03:13 10:33 17:52
Moon 16:31 21:33 01:55
Mars 05:58 13:07 20:17
Jupiter 11:43 17:27 23:12
Saturn 16:58 21:45 02:36
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

29 Jul 2017, 20:24 EDT  –  Mercury at greatest elongation east
12 Sep 2017, 05:11 EDT  –  Mercury at greatest elongation west
23 Nov 2017, 21:22 EST  –  Mercury at greatest elongation east
01 Jan 2018, 19:40 EST  –  Mercury at greatest elongation west

Image credit

© NASA/JPL/MESSENGER

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

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