The Orionid meteor bathe is one in every of autumn’s main meteor showers and is a agency favorite with shooting-star watchers. For this yr’s return, charges of Orionids are predicted to peak at midnight on 21/22 October, though the bathe displays no sharp most and charges ought to stay good between 21–23 October.
Meteor showers are seen when Earth encounters minuscule particles left behind normally by periodic comets; a few of their materials is ejected owing to floor heating that happens on their repeated journeys to the inside Photo voltaic System. Over time, particles are unfold across the orbit of the comet, and when Earth’s orbit intersects this stream, particles enter the environment and are vaporised, producing streaks of sunshine. The Orionids originate from the orbital particles stream left behind by Halley’s Comet (1P/Halley), probably the most well-known ‘icy snowball’ of all.
From a fairly darkish location, as many as 10–20 meteors could also be seen, although how good your native sky situations are has an enormous say in what number of fainter Orionids you’ll see. Fortunately, the Moon is at a really beneficial phase this yr; a 12 per cent-illuminated waning crescent rises in Leo at about 3.30am. Solely watches performed over the past hours earlier than daybreak could also be marred.
All meteor showers are given a determine known as a ZHR, the zenithal hourly charge, the seemingly charge of meteors seen by a single observer assuming the bathe’s radiant lies on the zenith in a darkish sky. This determine is getting on for double the precise seen charge of meteors.
Within the years from 2006 to 2009, the Orionids produced stronger returns, with a ZHR of 40–70 over consecutive nights. Between 2012 and 2019, the ZHR fell to between 20 to 30 meteors. The query of a suspected 12-year periodicity in stronger returns stays, although proof for that is seen in radar information moderately than visible and enhanced charges usually are not predicted for this yr. Nevertheless, in widespread with all meteor showers, one must be out observing beneath the celebs as can by no means be completely positive that the expected charge of meteors will probably be appropriate.
The Orionids produces quick meteors, zipping via the Earth’s tenuous outer environment at round 67 km/sec, and plenty of go away lingering trains, or trails.
Bathe meteors seem to streak away from some extent within the sky known as the radiant. The place of this radiant is decided by the Earth’s trajectory via the meteor stream orbit. The Orionid radiant is positioned round two levels north-east of magnitude +4.4 xi Orionis, roughly between sensible Betelgeuse (alpha Orionis) and magnitude +1.9 Alhena (gamma Geminorum). The meteors are at their brightest when 30 to 40 levels from the radiant, so it’s good to visualise the place they appear to come back from to work out if they’re real Orionids. In the course of the course of an evening you will notice many random (sporadic) meteors which aren’t a part of any bathe.
The Orionid radiant rises at about 10pm BST, although you’ll revenue by laying aside your meteor watch till no less than between midnight and 1am, by which period the radiant has climbed to an affordable altitude above the japanese horizon; it lies 30° excessive within the east by 1.30am BST.
Nevertheless lengthy you plan to search for meteors it is best to gown appropriately for potential chilly climate by sporting loads of layers of heat clothes, together with a wooly hat and a pair of gloves. Even have a sizzling drink and a few snacks at hand to maintain you going. Get comfortably sitting in a reclining chair and take a look at turn out to be totally darkish tailored (for no less than 15–20 minutes) earlier than beginning a watch and use solely a crimson torch for illumination.
