Mars's 687-day orbit around the Sun will carry it to its furthest point to the Sun – its aphelion – at a distance of 1.67 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 aphelion it will not be observable – it will reach its highest point in the sky during daytime and will be no higher than 12° above the horizon at dawn.
A chart of the path of Mars across the sky in 2017 can be found here, and a chart of its rising and setting times here.
The position of Mars at the moment it passes aphelion will be:
| Object | Right Ascension | Declination | Constellation | Magnitude | Angular Size |
| Mars | 11h26m30s | 4°52'N | Leo | 1.8 | 3.7" |
The coordinates above are given in J2000.0.
The sky on 7 Oct 2017
| The sky on 7 October 2017 | ||||||||||||||||||||||||||||||||||
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90% 17 days old |
All times shown in EDT.
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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
| 29 Jun 2016 | – Mars ends retrograde motion |
| 26 Jun 2018 | – Mars enters retrograde motion |
| 27 Jul 2018 | – Mars at opposition |
| 31 Jul 2018 | – Mars at perigee |
Image credit
© NASA/Hubble Space Telescope