Due to the usual cold weather, it’s hard to spend much time outside to watch, said Beverly Thackeray, a doctoral student in astronomy at the University of Maryland. “But if the conditions are right, and you can see the night sky, it is probably the best meteor shower of the year. So, grab some hot cocoa and get some sleeping bags,” she said.
The Geminids are known for producing some fireballs, Thackeray said.
Meteors will likely start late in the evening Wednesday and go throughout the night. All you have to do is turn off porch and house lights, go outside, get your eyes acclimated to the dark and begin looking up. The waning crescent moon will be in a last-quarter phase, and it’s not going to rise until about 3:45 a.m., which means the sky will be plenty dark. If you’re in an area with bright light pollution, like a major city, you may want to head out to the far suburbs to get the best view.
Usually, meteors occur when Earth passes through the dusty trails of comets. When comets approach the sun, they form a tail, spewing vapor and dirt. As our planet rounds the sun on its annual 365-day journey, the Earth’s atmosphere inevitably strikes debris from these leftover comet trails. The dust burns in our atmosphere, lights up and shoots across our heavens.
The Geminid meteors are different. They occur thanks to a rocky asteroid called (3200) Phaethon, a carbonaceous entity about 3 miles in diameter that voyages close to the sun, heats up, and releases dust. When Earth runs into these rocks, they burn up.
There is much to learn about these asteroids. Matthew Knight and Michael Kelley, astronomy researchers at the University of Maryland, will travel this week to Happy Jack, Ariz., to use the Lowell Observatory’s behemoth Discovery Channel Telescope around Phaethon’s close approach (it won’t hit us) to Earth.
Phaethon passes Earth every 1.4 years, and it will pass closer to Earth on Dec. 16 than ever since its discovery in 1983. It will pass this close again in 2093, Knight said. At this week’s pass, the asteroid will be about .07 astronomical units or about 6.5 million miles away — the equivalent of about 30 trips between our pale blue planet and the moon.
In this scientific hunt to understand Phaethon, the Maryland researchers will exploit the telescope’s ability to rapidly switch between an optical imager, an optical spectrograph and an infrared spectrograph.
Phaethon is a B-type asteroid that could be similar to some carbonaceous chondrites, which could contain organic molecules — the stuff of life. Some of these kind of meteorites — broken off from asteroids — may have been cosmic couriers that brought water to Earth. “That’s a pretty profound thing in geology,” said Sam Crossley, a doctoral student in planetary geology at Maryland and a NASA Harriet Jenkins Fellow. “It’s one of the holy grails of planetary science — finding where water came from.”
To root out the genesis of life, scientists are on the case. Phaethon’s carbonaceous cousin, (101955) Bennu, another B-type asteroid, will get a visitor late in the summer. NASA launched the OSIRIS-REx mission spacecraft, part of the agency’s New Frontiers program, in September 2016. The craft will reach Bennu in August 2018, pluck samples from it and return to Earth with specimens in 2023.
Thackeray wishes to see more Geminid meteors in the future showers. The planet Jupiter’s immense gravity seems to be tugging Phaethon’s dusty trail more into Earth’s path. “Jupiter is pulling things, like it always does,” she said. “Jupiter is the ruler of the solar system. It’s the reason we have an asteroid belt to begin with. That’s why a planet didn’t accrete (coalesce) in the asteroid belt, because Jupiter wouldn’t allow that to happen.”
Will Jupiter continue to pull more of the asteroid’s trail into Earth’s path?
“Hopefully,” said Thackeray, who participates in the National Science Foundation’s Graduate Research Fellowship Program. “I hope this meteor shower continues to get more spectacular over time.”