© NASA/JPL/MESSENGER

Mercury at perihelion

Tue, 12 Dec 2017 at06:43 EST(Tomorrow)
11:43 UTC

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 17h24m40s -21°38' Ophiuchus 9.9"
Sun 17h18m -23°05' Ophiuchus 32'29"

The coordinates above are given in J2000.0.

From Ashburn (click to change), Mercury will not be readily observable since it will be very close to the Sun, at a separation of only 2° from it.

The sky on 12 December 2017
Sunrise 07:18
Sunset 16:46
Twilight ends
18:22
Twilight begins
05:42

24-day old moon
Age of Moon
24 days

All times shown in EST.
Rise Culm. Set
Mercury 07:18 12:06 16:55
Venus 06:48 11:34 16:20
Moon 01:56 07:52 13:47
Mars 03:17 08:43 14:10
Jupiter 04:14 09:28 14:41
Saturn 07:53 12:38 17:23

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

23 Nov 2017, 21:22 EST  –  Mercury at greatest elongation east
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

Image credit

© NASA/JPL/MESSENGER

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EST

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