© NASA/Hubble Space Telescope

Mars at perihelion

Dominic Ford, Editor
From the Outer Planets feed

Please wait
Loading 0/4
Click and drag to rotate
Mouse wheel to zoom in/out
Touch with mouse to dismiss
The sky at

Mars's 687-day orbit around the Sun will carry it to its closest point to the Sun – its perihelion – at a distance of 1.38 AU.

Unlike most of the planets, which follow almost exactly circular orbits around the Sun which only vary in their distance from the Sun by a few percent, Mars has a significantly elliptical orbit. Its distance from the Sun varies between 1.38 AU and 1.67 AU – a variation of over 20% – meaning that it receives 31% less heat and light from the Sun at aphelion as compared to perihelion.

Finding Mars

Mars's distance from the Sun doesn't affect its appearance. From Cambridge, at the moment of perihelion it will be visible in the evening sky, becoming accessible at around 19:09 (EDT) as the dusk sky fades, 16° above your south-eastern horizon. It will then reach its highest point in the sky at 21:17, 23° above your southern horizon. It will continue to be observable until around 00:47, when it sinks to 8° above your south-western horizon.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

A chart of the path of Mars across the sky in 2018 can be found here, and a chart of its rising and setting times here.

The exact position of Mars at the moment it passes perihelion will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 20h17m10s -24°34' Capricornus -1.7 18.1"

The coordinates above are given in J2000.0.

The sky on 16 September 2018
Twilight ends
Twilight begins

7-day old moon
Waxing Crescent


7 days old

Rise Culm. Set
Mercury 06:02 12:26 18:50
Venus 10:08 15:03 19:58
Moon 13:46 18:33 23:19
Mars 16:53 21:18 01:46
Jupiter 11:10 16:09 21:09
Saturn 14:37 19:11 23:45
All times shown in EDT.


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

27 Jul 2018  –  Mars at opposition
13 Oct 2020  –  Mars at opposition
08 Dec 2022  –  Mars at opposition
15 Jan 2025  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope




Color scheme