Jupiter at opposition

Dominic Ford, Editor
From the Outer Planets feed


Objects: Jupiter

Jupiter will reach opposition, when it lies opposite to the Sun in the sky. Lying in the constellation Leo, it will be visible for much of the night, reaching its highest point in the sky around midnight local time.

From Cambridge, it will be visible between 18:14 and 05:32. It will become accessible at around 18:14, when it rises to an altitude of 7° above your eastern horizon. It will reach its highest point in the sky at 23:53, 53° above your southern horizon. It will become inaccessible at around 05:32 when it sinks below 7° above your western horizon.

2016 apparition of Jupiter

07 Jan 2016 – Jupiter enters retrograde motion
08 Mar 2016 – Jupiter at opposition
08 Mar 2016 – Jupiter at perigee
09 May 2016 – Jupiter ends retrograde motion

A close approach to the Earth

At around the same time that Jupiter 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 Jupiter lies opposite to the Sun in the sky, the Earth passes between Jupiter and the Sun. The solar system is lined up with Jupiter and the Earth on the same side of the Sun, as shown by the configuration labelled perigee in the diagram below:


When a planet is at opposition, the solar system is aligned such that the planet lies on the same side of the Sun as the Earth. At this time, the planet makes its perigee, or closest approach to the Earth. Not drawn to scale.

The panels below show a comparison of the apparent size of Jupiter when seen at opposition in 2016, and when it is most distant from the Earth at solar conjunction.

Jupiter at 2016 opposition
Jupiter at solar conjunction

A comparison of the size of Jupiter as seen at 2016 opposition and at solar conjunction.

In practice, however, Jupiter orbits much further out in the solar system than the Earth – at an average distance from the Sun of 5.20 times that of the Earth, and so its angular size does not vary much as it cycles between opposition and solar conjunction.

Observing Jupiter

At opposition, Jupiter is visible for much of the night. When it lies opposite to the Sun in the sky, this means that it rises at around the time the Sun sets, and it sets at around the time the Sun rises. It reaches its highest point in the sky at around midnight local time.

But even when it is at its closest point to the Earth, it is not possible to distinguish it as more than a star-like point of light with the naked eye, though a good pair of binoculars is sufficient to reveal it as a disk of light with accompanying system of moons.

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

At the moment of opposition, Jupiter will lie at a distance of 4.44 AU, and its disk will measure 43.5 arcsec in diameter, shining at magnitude -2.5. Its celestial coordinates at the moment it passes opposition will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Jupiter 11h18m20s 6°04'N Leo -2.5 43.5"

The coordinates above are given in J2000.0.

Over the weeks following its opposition, Jupiter 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.

The sky on 8 Mar 2016

The sky on 8 March 2016
Sunrise
06:06
Sunset
17:43
Twilight ends
19:16
Twilight begins
04:32


Waning Crescent

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29 days old

Planets
Rise Culm. Set
Mercury 05:48 11:08 16:28
Venus 05:17 10:28 15:38
Moon 05:51 11:32 17:22
Mars 23:43 04:33 09:23
Jupiter 17:28 23:53 06:18
Saturn 00:56 05:37 10:19
All times shown in EST.

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

08 Mar 2016  –  Jupiter at opposition
09 May 2016  –  Jupiter ends retrograde motion
06 Feb 2017  –  Jupiter enters retrograde motion
07 Apr 2017  –  Jupiter at opposition

Image credit

© NASA/Cassini

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