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  • [♪ INTRO]

  • Asteroid 3200 Phaethon is a bit of a peculiar space rock.

  • For one thing, its orbit is super lopsided, more like a comet than an asteroid,

  • taking it from beyond Mars's orbit to twice as close to the sun as the planet Mercury.

  • In fact, it gets closer to the Sun than any other named object in the Solar System,

  • where its surface temperature soars to over 700 degrees Celsius,

  • nearly 300 degrees hotter than Venus, the hottest planet in the Solar System.

  • Also, it's blue. We're still working on why that is.

  • In a couple of upcoming studies, researchers got their closest look yet at

  • what it's actually like on Phaethon's surface.

  • Back in December of 2017, the asteroid got within 10.3 million kilometers of us,

  • about 27 times the distance from the Earth to the Moon.

  • That's closer than it will be until 2093, so astronomers wanted to use this window

  • to learn as much as they could.

  • At least four different teams from around the globe turned their telescopes toward Phaethon,

  • observing it using both radio waves and visible light.

  • And two of them presented their results at conferences in the past few weeks.

  • One team, out of Russia's Far Eastern Federal University,

  • was specifically looking at how light reflected off the asteroid's surface.

  • The researchers found that Phaethon seems to have three different types of surfaces, also called regolith.

  • The team also showed that it's possible to use the light coming from the asteroid

  • to figure out how reflective it is, which we've done with larger objects like

  • the moon in the past, but it's been harder to establish for asteroids.

  • The researchers' numbers weren't all consistent with what the

  • other teams studying the asteroid found, though.

  • Last week, a group out of the University of Arizona announced that they'd found

  • Phaeton's surface to be equally blue everywhere.

  • According to the team based out of Russia, the differences in the data could be a sign

  • that the asteroid is actually more varied,

  • with the side of it seen by each telescope reflecting light differently.

  • Either way, we have a lot to learn about this peculiar object, like why it's blue.

  • Astronomers think the unusual color is the result of the sun's heat,

  • but they still don't know exactly what's going on.

  • Meanwhile, other researchers have been studying parts of the universe

  • that are much, much, much farther away.

  • In a paper featured by NASA a few weeks ago, a group of astronomers made the very first

  • observations of a supermassive black hole's magnetic field helping to feed it.

  • Black holes, as some of the most extreme objects in the universe, come in a variety of sizes.

  • The largest can get as massive as several billion times that of our Sun.

  • And it's been a scientific theory for decades that each galaxy has, at its heart,

  • some kind of supermassive black hole.

  • For about 99% of these black holes, they just sit there, just minding their own business.

  • But for a special few, they voraciously consume all the matter they can get their proverbial mouths on.

  • Their intense gravity causes dust and gas to spiral down toward them, and in the process,

  • they emit a lot of radiation all across the electromagnetic spectrum.

  • The elliptical galaxy Cygnus A is about 600 million light years away from us.

  • That makes it the closestactive galaxy”, meaning its central black hole is actively eating.

  • The team wanted to use Cygnus A to figure out how active galaxies can generate a sort of

  • donut-shaped structure full of gas and dust around them, called a torus.

  • And they studied it using what's probably the coolest telescope you've never heard of:

  • NASA's SOFIA telescope, which flies around in a modified 747 with a giant

  • hole in the side of it so the telescope can see out.

  • Why didn't anyone tell me about this?

  • With one of its newest cameras, they were able to detect infrared light from the galaxy's

  • surrounding torus for the first time, which they could then use to

  • figure out what the magnetic fields were up to.

  • By comparing this data against some captured by other telescopes, it looks like magnetic

  • fields produced by the active galactic nucleus are acting like a giant net,

  • trapping the torus's contents close enough to the black hole so it can keep eating.

  • Before this research, astronomers were really only taking gravity into consideration when

  • analyzing how supermassive black holes feed.

  • Now we know electromagnetism plays a crucial role, too.

  • With more studies of Cygnus A and other galaxies, both active and not, astronomers hope to get

  • a better understanding of the relationship between black holes and magnetic fields.

  • And in the process, maybe they'll even figure out why so few supermassive black holes are active.

  • Thanks for watching this episode of SciShow Space News!

  • We love being able to geek out with you about everything going on in the world of space

  • research and exploration, and the reason we're able to make videos like this

  • is because of our community on Patreon.

  • If you want to learn more about how you can help, check us out at patreon.com/scishow.

  • [♪ OUTRO]

[♪ INTRO]

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被一顆怪異的藍色小行星撞到了 (Buzzed By a Weird Blue Asteroid)

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    林宜悉 發佈於 2021 年 01 月 14 日
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