Tucson is the epicenter of a meteorite hunt after a shower of space rocks landed north of the city Tuesday night.
The event began at 7:11 p.m. with a window-rattling sonic boom, as a massive fireball entered the Earth’s atmosphere and broke apart. However, the fireball wasn’t precisely a “meteor.”
“Meteor is a phase, and not an actual thing. It’s a transient, luminescent event,” said Eric Christensen, a University of Arizona astronomer. “A meteoroid is what’s in space and passes through the atmosphere and if anything survives to hit the ground that’s what we call a meteorite. Very large meteoroids are called bolides. This may be classified as a bolide event.”
Christensen said Tuesday night’s fireball likely was unrelated to the Geminids meteor shower that is expected to peak over the next two days.
Christensen, as the principal investigator for the Catalina Sky Survey, said there is great scientific value in examining newly fallen meteorites.
“Anytime that we can get a fresh sample of a meteorite that hasn’t been contaminated from sitting on the ground for days or weeks or years — or centuries or millennia, for that matter — it’s a chance to examine a pristine sample of an asteroid,” he said.
Or at least “relatively pristine,” he said. “It is altered as it comes through the atmosphere, and as it sits on the ground, it begins the process of weathering.”
Because of the scientific value of the meteorites, Christensen encourages anyone who finds one to take a photo of it, and if possible, note the GPS coordinates and send them to the UA’s Lunar and Planetary Laboratory. If they wanted to collect the sample and give it to the lab, they should avoid handling it or using a magnet to test it for iron content.
“People will use magnets because a lot of meteorites contain iron. Once you do it, you scramble whatever remnant magnetic field was already in the meteorite, so you lose some of the information already by doing that,” he said. “Our hands have dirt and oil and moisture and any of that that starts to penetrate into the meteorite can contaminate it.”
He suggests rock hunters handle the meteorite as little as possible, put it in a bag and take it to the planetary lab.
“We learn an awful lot about the solar system — the early part of the solar system, the modern processes in the solar system — from studying meteorites,” said Mark Sykes, director and CEO of the Tucson-based nonprofit Planetary Science Institute. “They’re very valuable from a scientific standpoint … to collect, particularly if we can collect it shortly after it hits the ground. As soon as it comes through the Earth’s atmosphere, they start becoming affected by the environment. Being able to get to something very quickly is important.”
