Asteroid 11 Parthenope will reach opposition, the point at which it is more-or-less directly opposite the Sun when observed from the Earth, at 4.46 pm GMT on Friday 26 October 2020, when it will also be 1.36 AU (i.e. 1.36 times as far from the Earth as the Sun, or about 202 952 000 km), and be completely illuminated by the Sun. While it is not obvious to the naked eye observer, asteroids have phases just like those of the Moon; being further from the Sun than the Earth, 11 Parthenope is 'full' when directly opposite the Sun. As 11 Parthenope is only about 153.3 km in diameter, it will not be visible to the naked eye, but with a maximum Apparent Magnitude (luminosity) of 9.34 at opposition, it should be visible in the Constellation of Pisces to viewers equipped with a good pair of binoculars or small telescope.
11 Parthenope was discovered by Neapolitan astronomer Annibale de Gasparis, on 11 May 1850, the second of nine asteroids he discovered. It was named after the Siren Parthenope from Greek mythology, who was credited with the foundation of the city of Naples. The number 11 indicates that it was the eleventh asteroid discovered.
11 Parthenope has an 1483 day (3.84 year) orbital period and an eccentric orbit tilted at an angle of 4.63° to the plane of the Solar System, which takes it from 2.21 AU from the Sun (i.e. 221% of the the average distance at which the Earth orbits the Sun) to 7.70 AU from the Sun (i.e. 270% of the average distance at which the Earth orbits the Sun). As an asteroid that never comes within 1.666 AU of the Sun and has an average orbital distance less than 3.2 AU from the Sun, 11 Parthenope is classed as a Main Belt Asteroid.
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