Mercury at perihelion

Dominic Ford, Editor
From the Inner Planets feed

Objects: Mercury
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The sky at

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 23h08m30s -04°17' Aquarius 7.2"
Sun 22h02m -12°01' Aquarius 32'22"

The coordinates above are given in J2000.0.

From Ashburn, Mercury will become visible around 18:12 (EDT) as the dusk sky fades, 12° above your western horizon. It will then sink towards the horizon, setting 1 hour and 32 minutes after the Sun at 19:21.

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The sky on 16 February 2013
Twilight ends
Twilight begins

6-day old moon
Waxing Crescent


6 days old

Rise Culm. Set
Mercury 07:42 13:30 19:19
Venus 06:39 11:47 16:54
Moon 10:23 17:25 00:27
Mars 07:40 13:16 18:52
Jupiter 11:26 18:42 02:01
Saturn 23:39 05:03 10:24
All times shown in EST.


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.


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

16 Feb 2013  –  Mercury at perihelion
17 Feb 2013  –  Mercury reaches highest point in evening sky
04 Mar 2013  –  Mercury at inferior solar conjunction
29 Mar 2013  –  Mercury reaches highest point in morning sky

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