© NASA/JPL/MESSENGER

Mercury at perihelion

Dominic Ford, Editor
From the Inner Planets feed

Objects: Mercury
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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 04h58m20s 23°28'N Taurus 5.1"
Sun 04h56m 22°38'N Taurus 31'31"

The coordinates above are given in J2000.0.

From San Diego, Mercury will not be readily observable since it will be very close to the Sun, at a separation of only 0° from it.

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 6 Jun 2018

The sky on 6 June 2018
Sunrise
05:38
Sunset
19:54
Twilight ends
21:35
Twilight begins
03:57

22-day old moon
Waning Crescent

48%

22 days old

Planets
Rise Culm. Set
Mercury 05:41 12:49 19:57
Venus 08:12 15:21 22:29
Moon 01:08 06:52 12:40
Mars 23:25 04:28 09:32
Jupiter 17:14 22:36 03:59
Saturn 21:18 02:20 07:21
All times shown in PDT.

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

30 Apr 2018  –  Mercury at highest altitude in morning sky
04 Jul 2018  –  Mercury at highest altitude in evening sky
11 Jul 2018  –  Mercury at greatest elongation east
26 Aug 2018  –  Mercury at greatest elongation west

Image credit

© NASA/JPL/MESSENGER

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San Diego

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Longitude:
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32.72°N
117.16°W
PDT

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