October: Opposition attracts celestial observers

The Carina Nebula (NGC 3372) is a large, complex area of bright and dark nebulosity in the constellation Carina and is located in the Carina-Sagittarius Arm, which is generally thought to be a minor spiral arm of the Milky Way. The nebula is about 8500 light-years from Earth. Photo by MPAS member Nick Axaris

Mars oppositions occur every two years and two months – or, to be precise, every 779.94 days – and this year Mars opposition falls on October 14. A planet is said to be at opposition when Earth lies directly between it and the sun. As the planet sits in the opposite part of the sky to the sun, it’s positioned closest to Earth for its current ‘apparition’, or period of visibility. Before Mars at opposition, the last close conjunction of Mars and the almost full moon to feast your eyes on for 2020 will be on October 2-3.

Other conjunctions to look out for this month include Venus close to the crescent moon on October 14, Mercury and the thin crescent moon in the evening twilight of October 18, Jupiter and a close waning moon on October 22, followed on October 23 by Saturn and the waning moon.

Also occurring is the annual Orionid meteor shower. Orionids are active every year in October, this year peaking on the night of October 21. At its peak, there are potentially up to 15 meteors visible every hour. The Orionid meteor shower is the second meteor shower created by Halley’s Comet. 

The Eta Aquarids in May is the other meteor shower created by debris left by Halley’s Comet, which takes about 76 years to make a complete revolution around the sun. Halley’s Comet itself will next be visible from Earth in 2061.

Orionids are named after Orion because the meteors seem to emerge or radiate from the same area in the sky as the constellation. No special equipment or a lot of skill is required to view a meteor shower. All you really need is a clear sky and lots of patience. For optimum viewing, find a secluded spot away from the city lights. Once you have found your viewing spot, make sure you are comfortable – especially if you plan to stay out long. Meteor-watching can be a waiting game!

By Nerida Langcake
This article appeared in the October 2020 issue of the Mornington Peninsula Magazine.