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Geminid meteor mystery solved? It was a collision!

Geminid meteor: Dark hills with bright sky fading to dark blue at top, full of thin, white vertical streaks.
View at EarthSky Community Photos. | Josh Ashley of Amado, Arizona, made this composite image of Geminid meteors captured on December 14, 2022. Has a Geminid meteor mystery been solved?

Geminid meteor mystery

In a NASA blog post on June 14, 2023, Desiree Apodaca at Goddard Space Flight Center in Maryland described new insights about the annual Geminid meteor shower. She wrote it’s likely that:

… a sudden, powerful event – such as a high-speed collision with another body or a gaseous explosion, among other possibilities – created the Geminid stream.

And that’s interesting! That’s because most meteors in annual showers – like the Delta Aquariid meteors or Perseid meteors, coming up later this summer – are a result of icy comets orbiting the sun. So as comets move through space, they litter their orbits with debris. Thus, we get annual meteor showers when our planet Earth passes through a stream of comet debris.

But the Geminid meteors – which peak each year in December, to the delight of earthly stargazers – are different. For some decades, we’ve known the Geminids’ parent body isn’t a fragile, icy comet. Instead, it’s a more substantial, rocky asteroid: 3200 Phaethon.

Jamey Szalay of Princeton University, one of the authors of a new study, said:

What’s really weird is that we know that Phaethon is an asteroid, but as it flies by the sun, it seems to have some kind of temperature-driven activity. Most asteroids don’t do that.

So, it’s been a mystery: how can a rocky asteroid spawn a meteor shower?

The Parker Solar Probe provides a clue

Each winter, the Geminid meteors light up the sky as they race past Earth, producing one of the most intense meteor showers in the night sky. Now, a recent mission is providing new evidence that a violent, catastrophic event created the Geminids.

The Parker Solar Probe is studying the sun and circling close to our home star. As it does, it passes through clouds of dust grains from asteroid Phaethon that pelt the spacecraft. And these high-speed impacts create unique electrical signals, or plasma clouds. As NASA said:

These impact clouds produce unique electrical signals that several sensors on the probe’s FIELDS instrument pick up. The FIELDS instrument measures electric and magnetic fields near the sun.

Using this Parker Solar Probe data, the scientists modeled different formation scenarios for the Geminid meteor stream. What they found was that the violent scenario, modeling an impact with asteroid Phaethon or sudden gas explosion, best matched their observations. Watch the video below to see how the violent model best fit the data.

Bottom line: Data from the Parker Solar Probe helped scientists discover that the Geminid meteor shower is most likely the result of a violent event on asteroid Phaethon.

Source: Formation, Structure, and Detectability of the Geminids Meteoroid Stream


Read more: 2023 Geminid meteor shower: All you need to know

June 25, 2023
Astronomy Essentials

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