One evening during the last summer, shortly after sunset, a number of people gathered in a small league field, not far from my home, eagerly awaiting the darkness and the appearance of the stars. We had also gathered there because there was not much in the way of light pollution and we got a clear and unobstructed view to the northwest. As the sky got darker, we could finally see it: Comet NEOWISE, which showed a nice, curved tail.
“Not a bad show, considering we’re looking at a cosmic waste,” I told the comet viewer’s coterie. “Truly what we are looking at is a piece of debris in space; think of the beautiful tail as ‘cosmic bedding’; small pieces of dust and gravel left by NEOWISE, all cluttered in the solar system.”
If you step out before dawn over the next week or so, try to get an overview of cosmic bedding that has been left in space by an even more famous comet: Halley’s. We call the cosmic litter Orionid meteor shower. And 2020 will be an excellent year to look after them, as the moon will be a slender crescent, four days after the new phase and will have set before 1 p.m. 21.30 local time at night to their highest activity and does not pose any obstacle at all for potential meteor observers.
Related: How to see the best meteor showers in 2020
If December Geminids and August Perseids can be considered ranked as the “first string” among the annual meteor showers in terms of brightness and reliability, then the Orionids are on junior varsity. This year, they are scheduled to reach their maximum before sunrise on Wednesday morning (October 21).
The name “Orionid” comes from the fact that the radiation – the place in the sky from which the meteors appear to blow – is just above Orion’s second largest star, the red-haired Betelgeuse.
Currently, the Orion constellation appears in front of us on our journey around the sun and has not fully risen over the eastern horizon until after 1 p.m. 23 local daylight. When it is best several hours later, around noon. 5, Orion will be highest in the sky to the south.
But to see the largest number of meteors, do not look in the direction of the radiation, but rather about 30 degrees from it in the direction of the point directly above the head (zenith). Your clenched fist, held at arm’s length, is approximately 10 degrees wide, so looking up “three fists” from Betelgeuse will be where you can concentrate your vision.
Best times to see
Orionid’s visibility ranges from October 16 to October 26 with maximum activity of perhaps 15 to 30 meteors per hour on the morning of October 21. Go out before sunrise on one of these mornings, and if you spot a meteor, there’s about a 75% chance it’s probably a byproduct of Halley’s comet. The very first Orionid stragglers usually appear sometime in early to mid-November.
The best time to see starts from kl. 1 or 2 in the morning local daylight to the first morning light (around 05.45) when Orion is highest above the southern horizon. The higher in the sky Orion is, the more meteors appear all over the sky. The Orionids are one of only a handful of known meteor showers that can be observed equally well from both the northern and southern hemispheres.
Orionid meteors are usually weak and not well seen from urban locations, so it is suggested that you find a safe rural location to see the best Orionid activity.
“They are easily identified … by their velocity,” wrote authors David Levy and Stephen Edberg in their book, “Observer Meteors: The Association of Lunar and Planetary Observers’ Meteor Observer’s Guide” (Astronomical League, 1986). “At 66 kilometers per second, they look like fast streaks, faster of a hair than their sisters, Eta Aquarids in May. And like Eta Aquarids, the brightest family members tend to leave trains that last a long time. Fireballs are possible for three days after maximum. ”
This is undoubtedly connected in some way with the composition of Halley’s Comet.
Comets are the remnants of the earliest days of the solar system, the odd pieces of simple gases – methane, ammonia, carbon dioxide and water vapor – that became unused when the sun and the planets came into their present form. Meteoroids released into space from this comet waste are the remnants of a comet’s core. All comets eventually disintegrate in meteor swarms, and Halleys is well into that process at this point.
These small particles – which mainly vary in size from dust to sand grains – remain along the orbit of the original comet, creating a “rubble” in space. In the case of Halley’s comet, its dirty traces of dirt have been distributed more or less evenly throughout its orbit. When these small comet pieces collide with the Earth, friction with our atmosphere raises them to white heat and produces the effect popularly called “shooting stars”.
And Halley’s comet has left a legacy visible to us in the form of not just one, but two annual meteor showers. This is because its orbit approaches the Earth’s orbit in two different places. An intersection (referred to by Levy and Edberg) is in early May and produces a meteor show known as Eta Aquarids. The second point comes right now, in the middle to late October, when the Orionids are being produced.
At this point, Halley itself is approaching the far end of its long elliptical path around the sun beyond Neptune’s orbit. Its last visit through the inner solar system was in the winter of 1986. It arrives at the aphelion – its longest point from the sun, 5.28 billion miles (5.28 billion km) – in early December 2023. Then it begins its long journey back against the sun due to return in mid-summer 2061. If you were born anytime after 1983, you probably have a better chance than 50-50 of catching it on its next return.
But for people like myself – who are unlikely to be there when they return – the Orionids will give us a chance to at least get an overview of some of the cosmic waste that Halley has left behind.
Joe Rao works as an instructor and guest lecturer at New York’s Hayden Planetarium. He writes on astronomy for the journal Natural History, Farmers’ Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook.