© NASA/JPL/MESSENGER

Mercury at perihelion

Dominic Ford, Editor
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Ashburn
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 00h22m20s +03°30' Pisces 6.4"
Sun 23h21m -04°07' Aquarius 32'12"

The coordinates above are given in J2000.0.

From Ashburn (click to change), Mercury will be difficult to observe as it will appear no higher than 12° above the horizon. It will become visible at around 18:26 (EDT) as the dusk sky fades, 12° above your western horizon. It will then sink towards the horizon, setting 1 hour and 26 minutes after the Sun at 19:33.

The sky on 10 March 2018
Sunrise
06:28
Sunset
18:10
Twilight ends
19:39
Twilight begins
04:59

23-day old moon
Waning Crescent

40%

23 days old

Planets
Rise Culm. Set
Mercury 07:05 13:20 19:35
Venus 07:09 13:14 19:19
Moon 02:05 07:00 11:55
Mars 01:56 06:38 11:20
Jupiter 23:13 04:21 09:25
Saturn 02:45 07:30 12:16
All times shown in EST.

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 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

01 Jan 2018, 19:40 EST  –  Mercury at greatest elongation west
15 Mar 2018, 06:18 EDT  –  Mercury at greatest elongation east
29 Apr 2018, 11:06 EDT  –  Mercury at greatest elongation west
12 Jul 2018, 00:00 EDT  –  Mercury at greatest elongation east

Image credit

© NASA/JPL/MESSENGER

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EDT

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