Mercury at perihelion

Dominic Ford, Editor
From the Inner Planets feed


Objects: Mercury

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 09h44m20s 14°36'N Leo 6.2"
Sun 10h44m 7°57'N Leo 31'42"

The coordinates above are given in J2000.0.

From Fairfield, Mercury will be visible in the dawn sky, rising at 04:54 (EST) – 1 hour and 24 minutes before the Sun – and reaching an altitude of 11° above the eastern horizon before fading from view as dawn breaks at around 05:59.

The sky on 2 Sep 2018

The sky on 2 September 2018
Sunrise
06:18
Sunset
19:24
Twilight ends
21:01
Twilight begins
04:40


Waning Gibbous

52%

22 days old

Planets
Rise Culm. Set
Mercury 04:56 11:52 18:47
Venus 10:13 15:31 20:49
Moon 23:02 06:05 13:16
Mars 17:48 22:12 02:35
Jupiter 12:00 17:04 22:09
Saturn 15:36 20:14 00:52
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 DE430 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

28 Aug 2018  –  Mercury at highest altitude in morning sky
06 Nov 2018  –  Mercury at greatest elongation east
10 Nov 2018  –  Mercury at highest altitude in evening sky
13 Dec 2018  –  Mercury at highest altitude in morning sky

Image credit

© NASA/JPL/MESSENGER

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