Asteroid3200 Phaethonis the archetypal sungrazer , and yet shows some very rum behavior on the hottest part of its eye socket . comet splendidly evaporate ice the closer they get to the Sun , leaving a bright trail of dust and rock and gas behind them . Asteroids , being mainly rock not ice , famously do not , and yet Phaethon gets more active the closer it draw to the Sun . A newfangled hypothesis suggests this is a result of sodium fizzing from inside like a sherbet bomb in your backtalk .
Since its discovery , theoddly bluePhaethon has been happen to undergo strange comet - alike behaviour as it draw end the Sun , brightening as material streams off it . However , the fickle substances in a comet ’s tail would have been lost from Phaethon ’s control surface many jillion of years ago , if it ever had them . A paper in thePlanetary Science Journalhas given astronomers an account .
In ancient Greek mythology , Phaethon was the Logos of Helios who endeavor to tug his Fatherhood ’s Sun - comport chariot across the sky with disastrous consequences . The name was thought appropriate for the 6 - km ( 3.6 - mile ) wide rock that do closest to the Sun of any named asteroid ( a few belittled unnamed bodies have been detected getting closer still ) .
When Phaethon gets closes to the Sun – a space half that of Mercury – its daytime temperature reaches 750ºC ( 1,400ºF ) . Exposure to that kind of heat has serious consequence . Most meteoroid showers are the result of dust left behind by comet hitting the Earth ’s atmosphere after the icing tie down it together unfreeze . The Geminids , one of the twelvemonth ’s best meteor showers , is produced by material lost from Phaethon , raising the question of how the dust miss .
" Phaethon is a singular objective that gets active as it approaches the Sun , " head authorDr Joseph Masieroof Caltech say in astatement . " We know it ’s an asteroid and the source of the Geminids . But it incorporate little to no ice , so we were intrigue by the possibility that sodium , which is comparatively plentiful in asteroid , could be the constituent driving this activity . "
The Geminids gave the clue ; they miss the distinctive orangish tincture of burning atomic number 11 some other meteor showers video display . Since Phaethon should once have been plentiful in sodium , its separation from the dust that make the annual pre - Christmas fireworks presentation requires excuse .
In a vacuum , Na turn to gun at temperature low enough any on Phaethon ’s open would have boil off long ago . However , Masiero and co - authors wondered what would happen to sodium locked in materials like feldspar further in .
They propose it vaporizes and then finds its way through cracks in the rock music – an inevitable product of the utmost heat and cooling the asteroid undergoes in an celestial orbit that takes it out past Mars .
“ Asteroids like Phaethon have very weak gravity , so it does n’t take a lot of force to kick debris from the surface or dislodge rock from a cracking , co - authorDr Björn Davidssonfrom NASA ’s Jet Propulsion Laboratory say . “ Our model suggest that very small quantity of sodium are all that ’s call for to do this – nothing explosive like the erupting vaporization from an frigid comet ’s surface ; it ’s more of a steady fizz . ”
If the authors are right , the sodium - use up dust on Phaethon ’s surface , and the sodium from within that gives it a push , part company long before they reach Earth .
To test their theory , Masiero and carbon monoxide - authors heated samples from the Allende meteorite , considered nigher to Phaethon ’s composition than most and containing 0.5 percent sodium , to temperature up to 800ºC. In the three hour that match a Phaethon day the sodium pour out out , but Allende ’s other element stayed put , supporting their case .
astronomer havestarted to questionthe bare binary of comets and asteroids . As Masiero said : “ If the conditions are right , Na may explain the nature of some participating asteroids , make the spectrum between asteroids and comets even more complex than we previously realized . ”
