Dominic Ford, Editor
From the Outer Planets feed
From Ashburn, it will be visible between 20:12 and 05:37. It will become accessible at around 20:12, when it rises 20° above your eastern horizon, and then reach its highest point in the sky at 00:56, 60° above your southern horizon. It will become inaccessible at around 05:37 when it sinks to 21° above your western horizon.
Uranus opposite the Sun
This optimal positioning occurs when Uranus 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 Uranus 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 Uranus lies opposite the Sun in the sky, the solar system is lined up so that Uranus, the Earth and the Sun form a straight line with the Earth in the middle, on the same side of the Sun as Uranus.
In practice, however, Uranus orbits much further out in the solar system than the Earth – at an average distance from the Sun of 19.29 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, Uranus will lie at a distance of 18.91 AU, and its disk will measure 3.7 arcsec in diameter, shining at magnitude 5.7. 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.
Uranus in coming weeks
Over the weeks following its opposition, Uranus 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 Uranus 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 October 2017|
29 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 Oct 2017, 13:21 EDT||– Uranus at opposition|
|23 Oct 2018, 20:33 EDT||– Uranus at opposition|
|28 Oct 2019, 04:02 EDT||– Uranus at opposition|
|31 Oct 2020, 11:40 EDT||– Uranus at opposition|
© NASA/Voyager 2