Last week, the Cassini probe dove into Saturn, never to be heard from again -- and to be
honest, I’m still recovering.
But thankfully, Cassini wasn’t the only probe out there. This month, two other spacecraft
reminded us that they’re still around -- just in case we forgot.
And farther from home, we’ve also found that an exoplanet we’ve studied before might
be even darker and stranger than we thought.
On Monday last week, we heard from the New Horizons spacecraft for the first time in months.
You remember New Horizons. Good old spacecraft. It was launched in 2006 and arrived at Pluto
in 2015 -- giving us the best view we will have of our favorite dwarf planet for decades.
Sorry, Ceres. Stop looking at me like that!
The Pluto encounter could’ve been the end of its mission, but the ship still had plenty
of fuel, and its instruments were working pretty perfectly.
So just like Cassini, Voyager, Opportunity, and lots of other missions, New Horizons was
extended for a few years.
Scientists aimed it at a rocky object called 2014 MU69, and then, back in April, they put
it to sleep until it got closer.
We didn’t discover MU69 until three years ago, when New Horizons was still focused on Pluto.
And we don’t know much about it other than that it’s in the Kuiper Belt, a region where
some debris ended up after the solar system formed. We do think MU69 isn’t more than
50 kilometers across, but it’s hard to know more because it’s so far away.
It might also be a binary system, with two objects instead of one.
We’ll know a lot more after New Horizons gets there at the beginning of 2019 and studies
what it’s made of and its structure.
But it’s a long trip, so New Horizons will hibernate on the way, with a couple mid-course
wake-up calls.
And the first automatic wake-up came last week. And it woke up which is great news.
The spacecraft, which is almost six billion kilometers away, will spend the next three
months checking out other Kuiper Belt objects from a distance, and will also measure radiation
and other conditions in the area.
Then, after a quick course adjustment in December, the probe will go back to sleep again until next June.
But if you can’t wait that long for your space probe fix, don’t worry. NASA’s got
you covered with OSIRIS-REx, a deep space probe that just swung by Earth.
It launched about a year ago, and its mission is to visit the asteroid Bennu in 2018, collect
a sample, and return it to Earth.
Which is just incredible, that that’s even a thing we can imagine doing.
Bennu has been out there since the early solar system, and scientists will use the sample
to understand the conditions from back when Bennu and the planets were both forming.
OSIRIS-REx has been orbiting the Sun for the last year, but today, it flew by Earth and
used the Earth’s gravity as a slingshot to get it on the right path to Bennu.
It was so close that if you live in eastern Australia, you could have seen it with a good
camera just after midnight local time on September 23rd. And I know that that sounds like, it’s
September 22nd when we uploaded this and it’s September 23rd but timezones are a thing..
Very weird.. Australia’s confusing.
So Cassini might be gone, but there’s still plenty of solar system exploration to look forward to.
Unfortunately, we will not be sending anything to exoplanets -- planets outside of our solar
system -- any time soon. But even though we’re limited to telescopes, we’re still making
sweet discoveries.
Last week, astronomers published a paper in The Astrophysical Journal Letters where they
show that one of the best-studied exoplanets might be even darker and reflect less light
than fresh asphalt.
The planet is a gas giant called WASP-12b, and it orbits a roughly Sun-like star about
1400 light-years away.
To measure how reflective it is, the team used the Hubble Space Telescope to watch the
planet’s host star when 12b dipped behind it.
If a planet is reflective, it magnifies the star’s light like a mirror, so the star
looks brighter from Earth. But when the planet passes behind the star and is hidden from
view, that effect goes away, and the star looks dimmer.
The dimmer the star looks, the more reflective we know the planet is.
Now, with 12b, there wasn’t much of a change, and observations showed that it absorbs more
than 90% of the light that hits it. That’s way darker than the stuff in our solar system,
and darker than we think most similar planets are.
And that isn’t the first interesting thing we’ve learned about WASP-12b.
Previous studies found that, because it orbits so closely to its star -- about 50 times closer
than the Earth does to its Sun -- the star’s gravity squishes it into an egg shape and
strips off its atmosphere.
It’s also tidally locked, so only one side ever faces the star. And all these effects
give it some pretty extreme conditions.
The new study confirms that its day side is about 2600 degrees Celsius -- so hot that
it glows, and molecules in the atmosphere break into individual atoms. Those atoms are
probably what absorb so much light.
Meanwhile, on the night side, which is a balmy 1200 degrees Celsius, previous studies have
found what looks like evidence of water vapor or clouds in the atmosphere. So the line between
day and night is pretty dramatic.
We’ve been studying 12b since 2008, but this new discovery proves that we still have
a lot more to learn even just by looking at it from 1400 light years away.
And it might be one of the strangest exoplanets out there, but this is definitely not one
you want to visit.
Thanks for watching this episode of SciShow Space News, brought to you by President of
Space, S. R. Foxley. If you’d like to help support this show or become President of Space
you can check us out at patreon.com/scishow. And if you want to support us just by watching
and by sharing and by knowing that these things exist because they show up in your subscription
box, go to youtube.com/scishowspace .