*
Asteroid 20 Massalia will be well placed,
lying in the constellation Pisces, well above the
horizon for much of the night.
Regardless of your location on the Earth, 20 Massalia will reach its
highest point in the sky around midnight local time.
From Los Angeles, it will be visible between 20:21 and 05:04. It will become accessible at around 20:21, when it rises to an altitude of 21° above your eastern horizon. It will reach its highest point in the sky at 00:43, 59° above your southern horizon. It will become inaccessible at around 05:04 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 20 Massalia 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 20 Massalia lies opposite to the Sun in the night sky, the
solar system is lined up so that 20 Massalia, the Earth and the Sun lie
in a straight line with the Earth in the middle, on the same side of the Sun
as 20 Massalia.
On this occasion, 20 Massalia will pass within
1.404 AU of us, reaching a peak brightness of
magnitude 9.2.
Nonetheless,
even at its brightest, 20 Massalia is a faint object beyond the reach of
the naked eye; binoculars or a telescope of moderate aperture are needed.
Finding 20 Massalia
The chart below indicates the path of 20 Massalia 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.
The position of 20 Massalia at the moment of opposition will be as follows:
| Object | Right Ascension | Declination | Constellation | Magnitude |
| Asteroid 20 Massalia | 00h24m10s | 3°03’N | Pisces | 9.2 |
The coordinates above are given in J2000.0.
The sky
on 29 Sep 2024
Source
The circumstances of this event were computed from
orbital elements
made available by Ted Bowell of the Lowell Observatory. The conversion to geocentric coordinates was performed using
the position of the Earth recorded in the
DE430
ephemeris published by the Jet Propulsion Laboratory (JPL).
The star chart above shows the positions and
magnitudes
of stars as they appear in the
Tycho catalogue.
The data was reduced by the author and plotted using
PyXPlot. A gnomonic
projection of the sky has been used; celestial coordinates are indicated in
the J2000.0 coordinate system.
Image credit
© NASA/Galileo 1993. Pictured asteroid is 243 Ida.
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