Asteroid 5 Astraea will be well placed, lying in the constellation Virgo, well above the horizon for much of the night.

Regardless of your location on the Earth, 5 Astraea will reach its highest point in the sky around midnight local time.

From Cambridge, it will be visible between 20:43 and 05:18. It will become accessible at around 20:43, when it rises to an altitude of 21° above your eastern horizon. It will reach its highest point in the sky at 01:00, 52° above your southern horizon. It will become inaccessible at around 05:18 when it sinks below 21° 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 5 Astraea 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 5 Astraea lies opposite to the Sun in the night sky, the solar system is lined up so that 5 Astraea, the Earth and the Sun lie in a straight line with the Earth in the middle, on the same side of the Sun as 5 Astraea.

On this occasion, 5 Astraea will pass within 1.189 AU of us, reaching a peak brightness of magnitude 9.4. Nonetheless, even at its brightest, 5 Astraea is a faint object beyond the reach of the naked eye; binoculars or a telescope of moderate aperture are needed.

Finding 5 Astraea

The chart below indicates the path of 5 Astraea across the sky around the time of opposition.

It was produced using StarCharter and is available for download, either on dark background, in PNG, PDF or SVG formats, or on a light background, in PNG, PDF or SVG formats.