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 02h52m40s 17°23'N Aries 5.4"
Sun 02h17m 13°45'N Aries 31'46"

The coordinates above are given in J2000.0.

From Fairfield, 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.

The sky on 26 Apr 2021

The sky on 26 April 2021
Sunrise
05:55
Sunset
19:44
Twilight ends
21:29
Twilight begins
04:11


Waning Gibbous

99%

14 days old

Planets
Rise Culm. Set
Mercury 06:17 13:22 20:28
Venus 06:21 13:21 20:21
Moon 18:00 00:02 05:52
Mars 09:00 16:39 00:19
Jupiter 03:17 08:33 13:50
Saturn 02:36 07:35 12:34
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

06 Mar 2021  –  Mercury at greatest elongation west
15 May 2021  –  Mercury at highest altitude in evening sky
17 May 2021  –  Mercury at greatest elongation east
05 Jul 2021  –  Mercury at greatest elongation west

Image credit

© NASA/JPL/MESSENGER

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