1 Ceres at opposition

Dominic Ford, Editor
From the Dwarf Planets feed


Objects: 1 Ceres

Across much of the world 1 Ceres will reach opposition, when it lies opposite to the Sun in the sky. Lying in the constellation Piscis Austrinus, it will be visible for much of the night, reaching its highest point in the sky around midnight local time.

From Fairfield however, it will not be readily observable since it will lie so far south that it will never rise more than 20° above the horizon.

A close approach to the Earth

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.

This happens because when 1 Ceres lies opposite to the Sun in the sky, the Earth passes between 1 Ceres and the Sun. The solar system is lined up with 1 Ceres 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.

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 brightness does not vary much as it cycles between opposition and solar conjunction.

Observing 1 Ceres

At opposition, 1 Ceres 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, 1 Ceres is so distant from the Earth that it is not possible to distinguish it as more than a star-like point of light, even through a telescope.

A chart of the path of 1 Ceres across the sky in 2075 can be found here, and a chart of its rising and setting times here.

At the moment of opposition, 1 Ceres will lie at a distance of 1.98 AU, and reach a peak brightness of magnitude 7.6. Its celestial coordinates at the moment it passes opposition will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
1 Ceres 21h34m30s 28°32'S Piscis Austrinus 7.6 0.0"

The coordinates above are given in J2000.0.

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 sky on 23 Nov 2024

The sky on 23 November 2024
Sunrise
06:48
Sunset
16:27
Twilight ends
18:04
Twilight begins
05:11


Waning Crescent

37%

22 days old

Planets
Rise Culm. Set
Mercury 08:37 13:04 17:30
Venus 10:14 14:41 19:08
Moon 23:20 06:15 12:58
Mars 20:49 04:12 11:35
Jupiter 17:22 00:49 08:16
Saturn 13:05 18:37 00:09
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.

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10 Aug 2075  –  1 Ceres at opposition
05 Nov 2076  –  1 Ceres at opposition
21 Feb 2078  –  1 Ceres at opposition
16 Jun 2079  –  1 Ceres at opposition

Image credit

© NASA/Dawn 2015

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