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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 closest “active 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!
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