One night last summer, shortly after sunset, a number of people gathered on a small league field not far from my house, looking forward to the night and the appearance of the stars. We had also gathered there because there was not much obstruction to light pollution and we were given a clear and unobstructed view of the northwest. When the sky darkened, we finally saw it: comet NEOWISE, showing a beautiful, curved tail.
“It’s not a bad show, considering we’re looking at space junk,” I told comet observers. “Indeed, what we are looking at is a piece of rubbish in space; think of this beautiful tail as a ‘space litter’; small pieces of dust and grit left by NEOWISE all bury the solar system.”
If you go out before dawn next week or so, you can try to capture a view of space debris left in space by an even more famous comet: Halley. We call this cosmic stretcher the meteor shower of Orionid. And 2020 will be a great year to look for them, as the Moon will be a thin crescent, four days after the new phase and will set before 9:30 p.m. Local time on the night of their peak activity and will not represent any be an obstacle for future meteor observers.
Connected: How to see the best meteor showers in 2020
If the December geminids and the August Perseids can be considered as the “first string” among the annual meteor showers in terms of brightness and reliability, then the Orionids are a junior university. This year, they should reach their maximum before sunrise on Wednesday morning (October 21).
The name “Orion” comes from the fact that the radiant – that spot in the sky where the meteors appear to deviate – is just above Orion’s second brightest star, the ruddy Betelgeuse.
At the moment, the constellation Orion appears before us on our journey around the sun and did not rise completely above the eastern horizon until after 23:00 local time. At best, a few hours later, around 5 a.m., 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 radiant, but rather about 30 degrees from it, in the direction of the point directly above (zenith). Your clenched fist, held at arm’s length, is roughly equivalent to 10 degrees wide, so looking “three fists up” from Betelgeuse will be the place to concentrate.
The best time to watch
The visibility of the Orionids extends from October 16 to October 26, with peak activity of about 15 to 30 meteors per hour coming on the morning of October 21. Go outside 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 last fallen Orionids usually appear sometime in early to mid-November.
The best time to watch begins at about 1 or 2 a.m. local summer time until the first light of dawn (around 5:45 a.m.), when Orion stands highest above the southern horizon. The higher in the sky is Orion, the more meteors appear throughout the sky. Orionids are one of the few known meteor showers that can be observed equally well in both the Northern and Southern Hemispheres.
Orionid meteors are usually weak and not well visible from urban areas, so it is recommended that you find a safe countryside to see the best Orionid activities.
“They are easily recognizable … by their speed,” write authors David Levy and Steven Edberg in their book, Observe Meteors: The Association of Lunar and Planetary Observers, A Guide for Meteor Observers (Astronomical League, 1986). “At 66 kilometers (41 miles) per second, they look like fast stripes, a hair faster than their sisters, the Eta Aquarids of May. And like the Eta Aquarids, the brightest members of the family tend to leave long-distance trains. balls are possible three days after the maximum. ”
Undoubtedly, this has something to do with Halley’s Comet’s make-up.
Comets are the remnants of the earliest days of the solar system, strange pieces of ordinary gases – methane, ammonia, carbon dioxide and water vapor – that remain unused when the sun and planets come to their present form. The meteoroids released into space from these cometary debris are the remnants of the comet’s nucleus. All comets eventually disintegrate into meteor swarms, and Halley is fine in the process at this point.
These tiny particles – mostly from dust to sand grains – remain in the orbit of the original comet, creating a “river of debris” in space. In the case of Halley’s Comet, its dirty trail of debris is more or less evenly distributed throughout its orbit. When these tiny pieces of comet collide with Earth, friction with our atmosphere lifts them to white heat and produces an effect popularly called “shooting stars.”
And Halley’s comet has left a legacy that is visible to us in the form of not just one, but two annual meteor showers. This is because its orbit is close to Earth’s orbit in two different places. One intersection (mentioned by Levy and Edberg) was in early May, producing a meteor display known as Eta Aquarids. The other point comes right now, in the middle to the second part of October, producing the Orionids.
At this point, Halley himself is approaching the far end of his long elliptical path around the sun, outside the orbit of Neptune. His last visit to the inner solar system was in the winter of 1986. He will arrive in Aphelion – its furthest point from the sun, 5.28 billion miles (5.28 billion km) – in early December 2023. Then he will begin his long journey back to the sun, which is due to return in the summer of 2061. If you were born at any time after 1983, you probably have a better chance of catching him 50-50 on his next return.
But for people like me – who probably won’t be around when he returns – the Orionids will give us a chance to at least catch a glimpse of some of the cosmic debris Halley left behind.
Joe Rao serves as an instructor and guest lecturer at the Hayden Planetarium in New York. He writes about astronomy for Natural History magazine, the Farmers’ Almanac and other publications. Follow us on Twitter @Spacedotcom and on Facebook.