It's big, it's blue, and it'll be raining down on you – it's 3200 Phaethon 3200 Phaethon, a weird object that sends cosmic debris streaking through Earth's night skies during the Geminid meteor shower, is more puzzling than previously thought. For starters, Phaethon appears to be blue. When the researchers viewed the object using telescopes in Hawaii and Arizona, USA, they found that it reflected …
That would it take it what, within 400 miles or so of the surface, depending on where you want to count the edge of our atmosphere? Normally something the size of a car coming closer than the 23,000 miles of geosynchronous satellites merits mention on the news for a "close call".
This thing is nearly 6 kilometers in diameter! If it came close enough to touch our atmosphere, we'd have been hearing about this potentially civilization ending body since we were kids!
This is truly interesting, but I know next to nothing about it. A couple of questions if I may.
1. It's blue. That's curious. Surely, someone has looked at it's reflectance spectra and maybe it's emission spectra as well if that's possible. What do the spectra have to say about its composition?
2. Is it true that objects are either asteroids or comets, rather than sort of falling on a continuous range between mostly frozen gases (comets) and mostly inert minerals (asteroids)?
3. The article suggests that Phaeton is in a highly elliptic orbit (it gets close to the sun) with a period of one year and pases through the Earth's atmosphere every December. Is that remotely possible? I understand how a diffuse cloud of debris can revisit the Earth at the same time every year -- at least for many, many repetitions. But a single, discrete object? If it actually passes through the Earth's atmosphere, won't its orbit decay/change on every pass?
Anybody have any insight?
To answer the questions.
1. To say that it's blue is rather a misnomer, the surface is very very dark, it just reflect slightly more of the blue light then it "should", I assume some group has tried looking at the reflected spectra, but as a general rule it's quite hard to figure out the composition from that.
2. Asteroids and comets are generally considered to be two separate populations of objects.
3. Phaeton don't pass through the atmosphere what happens is that the earth pass through the leftover debris that has spread out over the orbit. If indeed Phaeton had passed through the atmosphere it would likely very soon have resulted in one of two scenarios, either nudged about to cause an impact, or be flung out to a different orbit.
1. It's blue. That's curious.
If you could see it with your own eyes you'd say it was dark grey - the very slight tint of 'blueness' is only really discernible with instruments. Although we can learn stuff from how it reflects sunlight we can't get an emission spectra from it because it doesn't emit any light - we'd have to fly a projectile into it at a high enough speed to vaporise some of it to get it to produce light we could analyse.
2. Is it true that objects are either asteroids or comets...
I think it's true to say that people used to think that way but largely because we couldn't see as well as we can now, but with better instruments we've found bodies that seem to have characteristics of both types of body.
On the other hand though, there still seems to be two distinct groups of bodies, at least in terms of composition: one primarily composed of rock and one primarily composed of ice. Trouble is, we've only had a detailed look at a very small number of comets and asteroids - not enough to draw really solid conclusions.
3. The article suggests that Phaeton is in a highly elliptic orbit...
Yup, although it was only discovered in 1983 (because it's small and dark) its orbit is now very well known (it's orbital period is actually 1.433 years, not 1 year). At its greatest distance from the Sun it approaches the asteroid belt between Mars and Jupiter. As others have pointed though, it doesn't pass through Earth's atmosphere - its closest approach to Earth, at least since it was discovered, was in 2017 when it was ~6,400,000 miles away (the Moon is just 238,856 miles distant, so much further away then the Moon).
The orbit of 3200 Phaeton is pretty stable, at least for now, but each time it passes close the Sun a lot of dust and stuff gets cooked off of its surface and is released in to space. 3200 Phaeton isn't massive enough to simply draw that dust back in towards itself by gravity so the dust ends up orbiting the Sun along the same path as 3200 Phaeton itself, but getting more and more spread out along the orbit as time passes.
By now, enough time appears to have passed for this dust to have been spread out all the way around 3200 Phaeton's orbit so that every time the Earth crosses the orbit, each December, it will run into this dust and we'll get it entering the Earth's atmosphere and burning up as a meteors or shooting stars.
Thanks. Re composition: It crossed my mind while washing up after dinner that maybe some of the larger fragments might have made it down to the Earth's surface intact. Turns out that apparently no Geminid meteorites are known. But I did find this paper STRUCTURE AND COMPOSITION OF GEMINID METEOROIDS ...https://www.lpi.usra.edu/meetings/acm2008/pdf/8211.pdf These folks were able to get emission spectra from some of the burning meteorites. Don't know how they did that. It doesn't sound easy.
Anyway, they were able to measure relative Sodium, Iron, and Manganese content They concluded (I think) that based on Mg/Fe ratio, the Geminids look more like cometary material than asteroid material. I could probably decipher more if I knew more about meteorite composition.
Orbit is 523.5 days. Once a year we cross where its orbit has crossed Earth's orbit and thus the pre-existing trail of debris. That's why the Geminids meteor shower was a mystery till the object was spotted, no known comet parent for them. Geminids were first documented in 1862 and 3200 Phaethon in 1983.
"Then, as it whizzes through Earth’s atmosphere, bits and pieces of the object break off."
How to give away, in a single sentence of less than 20 words, that you have absolutely no understanding whatever of the subject you're writing about. Kind of impressive, in a way.
No, journos don't have to be experts on every topic, but surely to heaven someone in the team knows enough to have spotted this howler?
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