The asteroid3200 Phaethonis an secret , and not just because it passes closer to the Sun than any other asteroid we ’ve given a name . The visible radiation it reflects is unusually polarized light , and while the newspaper annunciate this fact has some potential explanations , all would bespeak something unexpended about this worldlet . The Japan Aerospace Exploration Agency ( JAXA ) is planning a missionary post past Phaethon , but it wo n’t even establish until at least 2022 , so answers may take some time .
If you ’ve had the pleasure of witnessing aGeminid meteor showeryou have Phaethon to give thanks . The asteroid is shedding junk grains and the Earth glide by through the detritus every December , producing one of the best annual shooting star showers ( check out our scout to 2018 ’s shooting star shower and how to watch themhere ) , recognize by its unusually slowly - go meteors . This is a strange affair in itself . Most shooting star showers are produced by particles discharge by comet as the ices that bind their junk together melt on advance to the Sun . Only one other asteroid is known to shed in a alike way .
It ’s not exculpated whether these unusual characteristics are have-to doe with to the specific feature article Dr Takashi Ito of the National Astronomical Observatory of Japan has investigated , Phaethon ’s strange blueish colouring material . One way to take this was to look at how polarise ( vibrate in a common plane ) the igniter we see from Phaethon is , look on the relative positions of the Earth , Sun , and asteroid . former researchhas show up a correlation between the maximum polarization of Light Within reflected off small objects within the Solar System and the size of it of the grains of debris on their surfaces .
InNature Communications , Ito has declare Phaethon ’s light is more than 50 percent polarized , the high record for a small Solar System object .
The paper offers three explanations . The particles on Phaethon ’s surface may be unusually large , which would also explain the blue tinge , as bigger particles ruminate more blue light . However , the authors note some past observations are n’t consistent with this hypothesis . A poriferous surface could also produce this polarisation .
The more challenging scenario is that Phaethon is darker than it looks , with light bouncing off it in a relatively straightforward way , rather than the multiple reflections that are plebeian from the loose collections of debris that make up most asteroids .
The right explanation probably reveals the effects of Phaethon passing seven times as snug to the Sun as the Earth ever get .
At 5.8 km across ( 3.6 miles ) Phaethon is noCeresorVesta , but is larger than other asteroid that cash in one’s chips inside Mercury ’s orbit . It was the first asteroid to be discovered using trope from a spacecraft , after analytic thinking from the Infrared Astronomical Satellite expose its presence in 1983 . Although it sometimes makes close approach to Earth , it acquaint no risk at least within the next 400 years .
