© NASA/Dawn 2015

1 Ceres at opposition

Dominic Ford, Editor
From the Dwarf Planets feed

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The sky at

1 Ceres will be well placed for observation, in the constellation Ophiuchus. It will be visible for much of the night, reaching its highest point in the sky at around midnight local time.

From Cambridge, it will be visible between 22:24 and 03:04. It will become accessible at around 22:24, when it rises 21° above your south-eastern horizon, and then reach its highest point in the sky at 00:46, 29° above your southern horizon. It will become inaccessible at around 03:04 when it sinks to 22° above your south-western horizon.

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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 1.76 AU, and its disk will measure 0.0 arcsec in diameter, shining at magnitude 7.0. 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.

A chart of the path of 1 Ceres across the sky in 2019 can be found here, and a chart of its rising and setting times here.

The position of 1 Ceres at the moment it passes opposition will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
1 Ceres 16h24m00s -17°42' Ophiuchus 7.0 0.0"

The coordinates above are given in J2000.0.

The sky on 28 May 2019
Sunrise
05:11
Sunset
20:09
Twilight ends
22:15
Twilight begins
03:05

24-day old moon
Waning Crescent

27%

24 days old

Planets
Rise Culm. Set
Mercury 05:37 13:17 20:56
Venus 04:14 11:15 18:16
Moon 02:34 08:16 13:57
Mars 07:13 14:54 22:36
Jupiter 21:03 01:42 06:17
Saturn 23:04 03:46 08:25
All times shown in EDT.

Source

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.

Related news

28 May 2019  –  1 Ceres at opposition
28 Aug 2020  –  1 Ceres at opposition
27 Nov 2021  –  1 Ceres at opposition
09 Dec 2022  –  1 Ceres at perihelion

Image credit

© NASA/Dawn 2015

Cambridge

Latitude:
Longitude:
Timezone:

42.38°N
71.11°W
EDT

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