Asteroid Phaethon May Be Losing Sodium As It Heats

Asteroid 3200 Phaethon, the origin of the dust that causes the Geminid meteor shower, may be losing sodium due to solar heating as it orbits.

Beth Johnson

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IMAGE: The Milky Way and a meteor from the Perseids meteor shower, taken from the White Desert in Egypt. CREDIT: Ahmed abd Elkader Mohamed

Has everyone been enjoying the Perseids meteor shower this year? I know there are a lot of sky issues with rain (for people who still get rain) and smoke, but I have seen some great astrophotography images on Twitter. There were also a couple of reports of large outbursts from several monitoring systems, including SETI Institute’s Cameras for All-Sky Meteor Surveillance program. The shower is still going despite being past its peak, so please continue to try and do some meteor watching.

What causes a meteor shower? When comets pass through our inner solar system, they are heated up by the Sun, and the closer they get, the more they shed their icy particulates and dust. Those particles all stay in the same orbit as the comet, although they trail behind a bit. And if Earth’s orbit ever crosses the orbit of those particles, they hit our atmosphere and burn up on entry, creating the bright streaks we see during meteor showers. Some will even be slightly bigger pieces that create bright fireballs.

Since we can track these meteors back to their orbits based on how they hit the atmosphere and the direction they came from, we can track them back and possibly determine the comet that left the dust trail. We call this comet, as it relates to a meteor shower, the parent body. For the Perseids, the parent body is Comet Swift Tuttle, which was discovered in 1862 and orbits the Sun every 133 years in an elliptical orbit.

Of course, the Perseids aren’t the only big meteor shower we get to see throughout the year. Coming up in December, we will have the Geminids meteor shower. Now, the parent body of this particular shower is really interesting as it’s not a comet. I know. I said comets are what cause meteor showers, but this is that one exception to the rule. The Geminids are caused by asteroid 3200 Phaethon, and this strange exception is one that has sent scientists looking for reasons why.

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Beth Johnson

Planetary scientist, podcast host. Communication specialist for SETI Institute and Planetary Science Institute. Buy me a coffee: https://ko-fi.com/planetarypan