Asteroid 4 Vesta at opposition

2019 Nov 12

Asteroid 4 Vesta will be well placed for observation, lying in the constellation Cetus, well above the horizon for much of the night.

Regardless of your location on the Earth, 4 Vesta will reach its highest point in the sky at around midnight local time.

From London, it will be visible between 19:30 and 04:13. It will become accessible at around 19:30, when it rises 21° above your eastern horizon, and then reach its highest point in the sky at 23:50, 46° above your southern horizon. It will become inaccessible at around 04:13 when it sinks to 22° above your western horizon.

The geometry of the alignment

This optimal positioning occurs when it makes its closest approach to the point in the sky directly opposite to the Sun – an event termed opposition. 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 4 Vesta passes opposition, it also makes its closest approach to the Earth – termed its perigee – making it appear at its brightest in the night sky. This happens because when 4 Vesta lies opposite to the Sun in the night sky, the solar system is lined up so that 4 Vesta, the Earth and the Sun lie in a straight line with the Earth in the middle, on the same side of the Sun as 4 Vesta.

On this occasion, 4 Vesta will pass within 1.563 AU of us, reaching a peak brightness of magnitude 6.5. Nonetheless, even at its brightest, 4 Vesta is a faint object beyond the reach of the naked eye or binoculars; a telescope of moderate aperture and a good star chart are needed.

Finding 4 Vesta

The star charts below mark the path of 4 Vesta across the sky around the time of its opposition.

This star chart is also available to download:

Light-on-dark PNG image PDF document
Dark-on-light PNG image PDF document

The exact position of 4 Vesta at the moment of opposition will be as follows:

Object Right Ascension Declination Constellation Magnitude
Asteroid 4 Vesta 03h17m00s +08°19' Cetus 6.5

The coordinates above are given in J2000.0.

This entry in the observing calendar was provided by In-The-Sky.org

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