Dominic Ford, Editor
From the Outer Planets feed
From Cambridge, it will be visible between 20:25 and 05:13. It will become accessible around 20:25, when it rises to an altitude of 7° above your south-eastern horizon. It will reach its highest point in the sky at 00:51, 33° above your southern horizon. It will become inaccessible around 05:13 when it sinks below 8° above your south-western horizon.
Jupiter opposite the Sun
This optimal positioning occurs when Jupiter 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 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 the Sun in the sky, the solar system is lined up so that Jupiter, the Earth and the Sun form a straight line with the Earth in the middle, on the same side of the Sun as Jupiter.
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.
On this occasion, Jupiter will lie at a distance of 4.01 AU, and its disk will measure 48.0 arcsec in diameter, shining at magnitude -2.9. 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 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.
Jupiter in coming weeks
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 position of Jupiter at the moment it passes opposition will be:
|Object||Right Ascension||Declination||Constellation||Magnitude||Angular Size|
The coordinates above are given in J2000.0.
|The sky on 19 August 2021|
11 days old
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.
|19 Aug 2021||– Jupiter at opposition|
|26 Sep 2022||– Jupiter at opposition|
|03 Nov 2023||– Jupiter at opposition|
|07 Dec 2024||– Jupiter at opposition|