Dominic Ford, Editor
From the Dwarf Planets feed
From Ashburn, it will be visible in the morning sky, becoming accessible at around 18:57, when it rises 21° above your north-eastern horizon. It will then reach its highest point in the sky at 00:41, 81° above your southern horizon. It will be lost to dawn twilight at around 06:10, 23° above your western horizon.
1 Ceres opposite the Sun
This optimal positioning occurs when 1 Ceres 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 1 Ceres 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 1 Ceres lies opposite the Sun in the sky, the solar system is lined up so that 1 Ceres, the Earth and the Sun form a straight line with the Earth in the middle, on the same side of the Sun as 1 Ceres.
In practice, however, 1 Ceres orbits much further out in the solar system than the Earth – at an average distance from the Sun of 2.77 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, 1 Ceres will lie at a distance of 1.60 AU, and its disk will measure 0.0 arcsec in diameter, shining at magnitude 6.8. 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.
1 Ceres in coming weeks
Over the weeks following its opposition, 1 Ceres 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 1 Ceres 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 31 January 2018|
14 days old
All times shown in EST.
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.
|31 Jan 2018||– 1 Ceres at opposition|
|23 Apr 2018||– 1 Ceres at perihelion|
|28 May 2019||– 1 Ceres at opposition|
|28 Aug 2020||– 1 Ceres at opposition|
© NASA/Dawn 2015