- December 11, 2017 - Planétarium Rio Tinto Alcan : Guided tour of the sky, Astronomical News
This year, conditions are in place for a rich spectacle of shooting stars. The maximum of Geminids is anticipated around 1:30 a.m. the night of December 13-14.
The radiant, the point in the sky where shooting stars appear to originate, located close to the star Castor in the constellation Gemini, is at that moment very high towards the south. The waning moon rises only at the end of night, without really hindering observations. So all you need to do is settle comfortably on a chaise longue in a cloudless spot without light pollution, dress warmly, and observe the starry sky – and don’t forget your end-of-year wish list!
The Geminid stream is remarkable for its consistency, its reliability and its richness, with as many as 100 meteors capable of being observed in one hour. The visibility period for this shower of shooting stars, the earliest observations of which go back to 1862, begins a few days before reaching its maximum, around December 14. The dust particles that make up the stream enter the Earth’s atmosphere at a low speed (around 36 km/h) and produce brilliant meteors, to the great joy of photographers. Indeed, the meteors readily leave their luminous trail on camera sensors.
A really close asteroid
This shower of shooting stars is associated not with a comet but with an asteroid named 3200 Phaethon, in honor of the son of the solar deity Helios in Greek mythology. Discovered in 1983 by the Infrared Astronomical Satellite (IRAS), this so-called Apollo asteroid, whose orbital period is 1.4 years, has a highly eccentric orbit that brings it, at perihelion (meaning at the closest point), to 20.9 million kilometers from the Sun (closer than Mercury, in other words). With a diameter of about 5.1 km, 3200 Phaethon has a rotation period of 3.6 hours. On December 10 it will find itself barely 10.3 million kilometers from the Earth.
Enjoy your observations, and may your wishes come true!