SAN FRANCISCO — The Parker Solar Probe is no one-trick pony.
Besides offering unprecedented close-ups of the sun, the spacecraft is giving new views of other parts of the solar system (SN: 12/4/19). The probe now has gotten the first-ever glimpse of the trail of space rubble responsible for the annual Geminid meteor shower. Future Parker observations of this debris could help solve the mystery of where the Geminids came from.
Earth’s orbit cuts through the stream of Geminid space rocks every December. The resulting shower of falling stars is expected to peak this year on December 13 to December 14.
Searches with ground-based observatories and the Hubble Space Telescope have never spotted the source of the Geminid meteors out in space. “All we’ve ever seen of the Geminids are the shooting stars in the sky,” says Karl Battams, a space scientist at the U.S. Naval Research Laboratory in Washington, D.C. Battams presented the work December 11 in news conference and December 9 in a poster presentation at the American Geophysical Union annual meeting.
In November 2018, during its first close encounter with the sun, the Parker Solar Probe spotted a very faint stretch of dust — about 100,000 kilometers wide and 20 million kilometers long — in the expected orbit of Geminid debris. Battams’ team estimated the mass of that debris trail to be about 1 billion metric tons. Based on the location and mass of the debris, the researchers determined they were looking at part of the Geminid meteor stream.
Parker’s outside perspective of the Geminids — as opposed to Earth’s view from within during meteor showers — may help uncover their origin. “The weird thing about the Geminids is that most of the other [meteor] streams, we associate with a comet,” says space scientist Jamey Szalay of Princeton University. As comets swing by the sun, they shed material to feed their meteor streams. But the Geminid meteor stream instead is associated with an asteroid called Phaethon, which loses hardly any material when it swoops past the sun.
“Something very violent maybe happened in the past, where a larger body lost a lot of its material” to create the crowd of Geminids and the remnant Phaethon asteroid, Szalay says. Pinning down the precise mass and distribution of material inside the Geminid stream may allow computer simulations to rewind the stream’s evolution and figure out how it was born.
The observations from Parker’s first orbit alone are not enough to reveal the Geminids’ origin, says David Jewitt, a planetary scientist at UCLA. “But it represents a point of hope.” Parker will view the same part of the meteor trail a few times each year over the next several years, potentially teasing out more structural details that contain clues about the space dust’s beginnings.