Got clear skies? Then be sure to bundle up: the Geminid meteors—one of the best, sure-fire annual meteor showers—peaks this weekend… and near a New Moon, to boot.
Geminid Prospects for 2020
After several off years, you couldn’t ask for a much better prospects for the Geminids. In 2020, the Geminids are expected to peak at 18:00 Universal Time (UT)/1:00 PM Eastern Standard Time (EST) on Sunday, December 13th with a predicted zenithal hourly rate (ZHR) of 120 meteors per hour, favoring the eastern Asia in the hour dawn hours. Keep in mind, though, that the peak of the Geminids is a broad one… and meteors showers don’t read astronomical predictions. Observers worldwide are encouraged to watch for the Geminids over the next several mornings, before and after the peak.
Aspects for the 2020 Geminids near the shower’s expected peak on Sunday, showing the relative position of the Earth’s shadow vs. the shower’s radiant, the Sun and the Moon. Credit: Dave Dickinson/Orbitron
The Moon phase is nearly perfect this year, as New Moon occurs just two days after the peak of the 2020 Geminids, along with a total solar eclipse over South America on the 14th.
The rising Geminid radiant at 10 PM local. Credit: Stellarium
In the 20th century, the Geminids were a relatively obscure shower. Fast-forward to the 21st century, and the Geminids have intensified, taking center stage as one of the strongest and best showers of the year, topping even the August Perseids. This happens as meteor streams evolve over time.
A 2017 Geminid fireball. Credit: The Virtual Telescope 2.0.
What you’re seeing when you see a meteor streak through the sky is an ionized trail in the wake of a cosmic dust particle zipping through the Earth’s tenuous upper atmosphere. Mostly, these are ancient streams of debris are laid down by comets where their orbits intersect the path of the Earth. These orbits evolve as they interact with other planets (mainly Jupiter) and disperse, while other undiscovered knotty clumps of debris move into the path of our planet and make themselves known.
The source of the Geminids is actually the strange ‘rock-comet’ 3200 Phaethon. Discovered in 1983, This bizarre object is like a ‘baked Alaska’ captured in an orbit that takes it from 2.4 Astronomical Units (AU) (223.2 million miles or 359.2 million kilometers) to a scorching perihelion 0.14 AU (13 million miles or 21 million kilometers) from the Sun once every 1.4 years. Is 3200 Phaethon a captured ‘dead comet nucleus,’ or some hereto unknown sort of object? Whatever the case is, 3200 Phaethon seems to shed a copious amount of material, and is deserving of further scrutiny. The Japanese Aerospace Exploration Agency’s (JAXA) DESTINY+ mission (the DEmonstration and Experiment of Space Technology for INterplanetary VoYage for Phaethon flyby) mission was once proposed to explore this enigmatic object, possibly launching in 2024. The Geminids have been observed every December since the mid-19th century, though 3200 Phaethon was only pinned down as the source for the shower by astronomer Fred Whipple shortly after its discovery in the early 1980s.
3200 Phaethon, as seen by the Arecibo Radio Observatory in 2017. Credit: Arecibo/NSF
Sigma Hydrid Fireball Photobomb(s)?
Another relatively obscure shower is making itself known in 2020: several early December fireballs have been pegged to the Sigma Hydrid meteors. Emanating from the southern hemisphere constellation of Hydrus the Water Snake, the Sigma Hydrids generally reach a paltry zenithal hourly rate of three per hour, just below the usual sporadic background rate… but several early fireball sightings suggest that 2020 may be different. If you can’t trace a meteor back to the Geminids’ radiant near the bright star Castor (Beta Geminorum) in the constellation of Gemini the Twins, then you may well have witnessed a rare Sigma Hydrid meteor.
A Geminid composite/timelapse, over the LAMOST telescope in China from 2014. Image credit and copyright: Steedjoy. Used with permission.
Don’t Forget the Ursids
Another December meteor shower is worthy of scrutiny. The Ursid meteors peak with a respectable ZHR of 15, right around the December 21st southward solstice. The source of the Ursids is the periodic Comet 8P/Tuttle, but the source of the Sigma Hydrids is unknown.
A one-night animation of the 2017 Geminids. Credit: The Virtual Telescope Project 2.0
Observing meteors is as simple as dressing warmly, laying back in a comfortable lawn chair, and diligently watching the sky via a simple pair of ‘mk-1 eyeballs.’ Look at about a 45-90 degree angle on either side of the radiant, to catch long stately meteor trains in profile. While it’s true that you always tend to see more meteors after local midnight towards dawn as you now stand on the part of the Earth turned forward, scooping out an enormous ~8,000-mile wide cavity is space… the Geminids are a bit different. The radiant of the shower rides high enough that you can start watching for meteors a bit early before local midnight, around about 10 PM local or so. Watch for those early meteors to leave long slow trails across the night sky, and for the tempo to accelerate from midnight towards dawn. Pick as dark a site as you can find, in order to optimize your chances of seeing as many Geminids as possible—even the slightest bit of suburban light-pollution can significantly kill how many meteors you’ll see.
Awaiting a night of skywatching at the Nebraska Annual Star Party. Credit: Dave Dickinson
Photographing meteors is as easy as using a wide-angle lens with a tripod mounted DSLR, shooting long exposure (30” to 3 minute) shots, and looking to see what turns up. I like to use an intervalometer to automate the process. Be sure to check out our recent guide to shooting meteor showers over on Astro-Gear Today.
A Tarantula (!) versus the 2017 Geminid meteors… Credit: The Virtual Telescope Project 2.0
Meteor watching is an ideal pursuit for 2020: you can do it alone, or as a physically-distanced activity, with observers space-out watching different swaths of the sky.
Count how many meteors you see over a set span of time, and you can contribute your observations to the science of meteoritics, by reporting your observations to the International Meteor Organization.
Good luck, and have a great weekend observing the 2020 Geminids.
-Be sure to watch the Geminids live courtesy of astronomer Gianluca Masi and the Virtual Telescope Project, starting on December 13th at 22:00 UT/5:00 PM EST.
Lead image: 2017 Geminids grace Arizona skies. Image credit and copyright: Robert Sparks. Used with permission.