© NASA/Hubble Space Telescope

Mars at opposition

Sun, 22 May 2016 at07:10 EDT(698 days ago)
11:10 UTC

Dominic Ford, Editor
From the Outer Planets feed

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Ashburn
The sky at

Mars will be well placed for observation, in the constellation Scorpius. It will be visible for much of the night, reaching its highest point in the sky at around midnight local time.

From Ashburn (click to change), it will be visible between 21:05 and 05:01. It will become accessible at around 21:05, when it rises 7° above your south-eastern horizon, and then reach its highest point in the sky at 01:05, 29° above your southern horizon. It will become inaccessible at around 05:01 when it sinks to 8° above your south-western horizon.

Mars opposite the Sun

This optimal positioning occurs when Mars is almost directly opposite the Sun in the sky. Since the Sun reaches its greatest distance below the horizon at midnight, the point opposite to it is highest in the sky at the same time.

At around the same time that Mars passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest and largest.

This happens because when Mars lies opposite the Sun in the sky, the solar system is lined up so that Mars, the Earth and the Sun form a straight line with the Earth in the middle, on the same side of the Sun as Mars.

The time of Mars's perigee is an especially good time to observe it, since it neighbors the Earth in the solar system and has the greatest variation of all of the planets in its distance from the Earth. This in turn leads to a large variation in its apparent size and brightness.

Mars's distance from the Earth can vary between 0.36 AU and 2.68 AU, meaning that its disk varies in diameter between 25.68" and 3.49".

When it passes opposition, Mars glides past the Earth rather quickly, and so only appears large and bright in the sky for a few weeks. A graph of the angular size of Mars at this opposition is available here, and a graph of its brightness is available here.

On this occasion, Mars will lie at a distance of 0.51 AU, and its disk will measure 18.4 arcsec in diameter, shining at magnitude -2.1. Even at its closest approach to the Earth, however, it is not possible to distinguish it as more than a star-like point of light without the aid of a telescope.

Mars in coming weeks

Over the weeks following its opposition, Mars will reach its highest point in the sky four minutes earlier each night, gradually receding from the pre-dawn morning sky while remaining visible in the evening sky for a few months.

A chart of the path of Mars across the sky in 2016 can be found here, and a chart of its rising and setting times here.

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

Object Right Ascension Declination Constellation Magnitude Angular Size
Mars 15h56m40s -21°36' Scorpius -2.1 18.4"

The coordinates above are given in J2000.0.

The sky on 22 May 2016
Sunrise
05:50
Sunset
20:21
Twilight ends
22:12
Twilight begins
03:58

16-day old moon
Waning Gibbous

99%

16 days old

Planets
Rise Culm. Set
Mercury 05:11 11:57 18:43
Venus 05:40 12:49 19:57
Moon 21:10 01:24 06:33
Mars 20:12 01:06 05:54
Jupiter 13:37 20:06 02:38
Saturn 21:02 01:59 06:51
All times shown in EDT.

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

22 May 2016, 07:10 EDT  –  Mars at opposition
27 Jul 2018, 01:07 EDT  –  Mars at opposition
13 Oct 2020, 19:19 EDT  –  Mars at opposition
08 Dec 2022, 00:35 EST  –  Mars at opposition

Image credit

© NASA/Hubble Space Telescope

Ashburn

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