The problem with trying to observe black holes is they’re really dark.
They don’t release the light from anything they swallow, and anything coming from their
surfaces is way too dim to see.
Also, black holes are so relatively tiny that it would take a telescope as wide as Earth
to even resolve the difference between the edge of the biggest black hole in our galaxy
and the swirling gas around it.
So we’ve only detected black holes indirectly, based on their gravity.
But soon we might have the first ever direct image of one, thanks to some astronomers with
an Earth-sized telescope.
It’s a project called the Event Horizon Telescope, or the EHT.
But it’s not like there’s a huge, mechanical second Earth floating around in space somewhere.
Instead, it’s a network of radio telescopes around the world that act like one virtual telescope.
Eight of these telescopes have spent a little over a week working simultaneously to collect
huge amounts of data.
They looked at the supermassive black hole in the center of our galaxy and the one in
the center of the galaxy M87.
A lot of a telescope’s strength comes from its width, so looking at something with telescopes
on opposite ends of the Earth is a lot like looking with a single telescope as wide as
the whole planet.
Except it’s a lot easier to build.
The Event Horizon team wants to use these telescopes to see the event horizons of black
holes – the points-of-no-return for anything falling in.
Supermassive black holes are usually surrounded by rapidly orbiting clouds of gas and dust
called accretion disks.
And light from quickly moving objects gets concentrated in the direction they’re moving,
so accretion disks are sort of like lighthouses.
They look really bright where gas and dust particles are moving toward us, and dimmer
where they’re not.
Researchers also expect to see light from the parts of accretion disks behind black
holes, because the light’s path will get bent by the extreme gravity.
Images of black holes could help us learn about things like why M87’s black hole has
huge jets of particles coming out while our galaxy’s doesn’t.
And the shape of the dark parts of black holes, called shadows, will also teach us a lot about
how gravity acts in a regime that we’ve never tested before.
If the shadows aren’t nearly a perfect circle, that could mean there’s something wrong
with our current theory of gravity.
Now, the EHT has gathered massive amounts of data over the last week, so it’s going
to take a while to analyze it all and hopefully produce an image.
But we could have the first-ever sharp picture of a black hole by sometime in 2018.
This other news is another first that you probably saw some headlines about.
Maybe even some misleading headlines.
A European team of astronomers announced the first detection of an atmosphere on an exoplanet
that’s about the same size as Earth in The Astronomical Journal.
Which is exciting!
But detecting an atmosphere doesn’t necessarily mean there’s life.
Exoplanets are planets orbiting stars other than the Sun, and their atmospheres are incredibly
hard to detect.
One way to do it is looking at how a host star’s light passes through the atmosphere
at the very the edge of an exoplanet.
Scientists have been detecting atmospheres around giant, gassy exoplanets for about a
decade, but it took until last year for them to find an atmosphere around what’s called
a super-Earth.
Super-Earths are exoplanets more massive than Earth and less massive than a planet like
Uranus or Neptune.
And the first one where we found an atmosphere is called 55 Cancri e.
But even though it’s a super-Earth, 55 Cancri e isn’t very Earth-like.
It’s 8 times more massive, with 18-hour years and surface temperatures of around 2,000
degrees Celsius.
So astronomers have been looking for atmospheres around planets that might be more like Earth.
And this team got a step closer.
GJ 1132 b is about 39 light years away.
It’s a super-Earth, but it’s only about 40% bigger and 60% more massive than Earth,
so it’s closer to Earth’s size than Mars is.
According to the team’s measurements, it’s probably made of similar rocks as Earth, too.
And the researchers think there’s a good chance that its atmosphere has lots of water vapor.
But they’ll have to collect more data to be sure, since water vapor and methane can
look really similar in these kinds of studies.
Now, even if there is a lot of water vapor in the atmosphere, there aren’t any warm
little ponds for life to swim around in.
Because GJ 1132 b is a toasty 320 degrees Celsius.
That doesn't necessarily mean it doesn't have life, but there probably isn't any like here
on Earth.
At the very least, GJ 1132 b is proof that Earth and Venus aren’t the only small, rocky
worlds with thick atmospheres out there.
And, who knows, it’s probably only a matter of time until we find a long-lost twin.
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