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Seven years after Elon Musk revealed it to
the world, SpaceX’s Falcon Heavy rocket
finally made its maiden test flight this past
Tuesday.
And, against all odds, it worked almost perfectly!
Which is definitely not what I was expecting
to say.
The original intent of this test launch was
just to get a payload into orbit around the
Sun and to prove the rocket works.
In this case, the payload was one of Elon
Musk’s Tesla Roadsters, instead of something
a little less flashy, like a block of concrete
with the same mass.
Now, that Roadster is orbiting the Sun as
the first private payload to go farther than
Earth’s orbit, along with a dummy named
Starman.
That’s one way to make the history books.
SpaceX launched the Falcon Heavy from Pad
39A at Kennedy Space Center in Florida, which
is the same pad that Apollo 11 used to get
to the moon almost 50 years ago.
Besides getting Elon’s Tesla into orbit,
they even managed to recover two parts of
the rocket’s first stage, or the part that
gets the rocket off the ground,
which touched down in a picture-perfect landing.
Unfortunately, the third part didn’t land
quite so smoothly.
But at least SpaceX can reuse two
of the boosters for future missions,
which saves a lot of time and money.
Now that we know it works, the Falcon Heavy
is officially the most powerful rocket humanity
has at its disposal, although it isn’t the
most powerful ever.
That honor still belongs to the Saturn V,
which sent us to the Moon.
But SpaceX hopes to use the Falcon Heavy to
go beyond our natural satellite, like to Mars.
It could also be used for missions to Low
Earth Orbit,
where it could launch up to 63.8 metric tons.
That’s equivalent to a fully-loaded 737
aircraft, or just a whole lot of satellites.
That power comes from the 27 engines in the
rocket’s first stage alone.
It has so many engines because, really, the
Falcon Heavy is like three of SpaceX’s smaller
rockets, called Falcon 9s, all lined up.
And each Falcon 9, as the name suggests, has
nine first stage engines.
Still, making sure that that many engines
work together perfectly is a huge challenge.
If they don’t…
things explode.
Which somehow did not happen on Tuesday.
Now that SpaceX knows their rocket works,
the next step is to launch their first commercial
payload: a satellite for a Saudi Arabian company
that will likely launch later this year.
Since that mission will be carrying something
arguably more important than a Tesla,
the stakes will be even higher.
So here’s hoping it goes just as well, and
that next time, they can land everything successfully.
While SpaceX was getting the Falcon Heavy
ready for launch, another group of astronomers
was publishing some even more
out-of-this-world news.
Last week in The Astrophysical Journal Letters,
they published the first evidence of planets
outside the Milky Way, in a galaxy almost
four billion light-years away.
That doesn’t seem possible, well, to find them,
they had to use one of the
many quirks of General Relativity.
Astronomers from the University of Oklahoma
analyzed the data of a quasar
about six billion light-years away
named RXJ 1131-1231.
Which is so memorable.
Quasars are extremely bright objects powered by the supermassive
black holes at the centers of galaxies.
And this one helped us track down those new
planets in another galaxy closer to home.
See, from Earth’s vantage point, 1131’s
quasar actually sits behind another galaxy
that’s much closer to us, about 3.8 billion
light-years away.
But we’re able to see it thanks to a
consequence of General Relativity
known as gravitational lensing.
This is where objects with a lot of mass,
like galaxies, bend, distort, and magnify
the light from objects behind them.
In this case, that means the intermediate
galaxy bent the quasar’s light like a lens.
These lenses help astronomers see things that
would otherwise be too dim.
But the technique isn’t helpful for studying
things as small and as dim as planets.
To find those objects, astronomers
use another, less powerful,
version of gravitational lensing
called microlensing.
For this method, astronomers have to
observe the lensed object,
in this case, the quasar,
a bunch of different times,
tracking how its brightness changes
as the lens’s position changes.
If they see any spikes in that brightness,
it means the object’s light was distorted
by planets hiding in the intermediate galaxy.
Microlensing has been used to find exoplanets
in the Milky Way, but this is the first time
that it’s been used to infer the presence
of planets anywhere outside our galaxy.
Now, to be clear, we don’t
have images of these planets.
They’re so far away that, I’m going to
go out on a limb and say we never will.
We only believe they’re there because
the quasar’s light signature
indicates there has to be a lot
of extra microlenses, and therefore,
a lot of planets, within the intermediate galaxy.
And I mean a lot of planets.
According to a computer program, you would
need about 2000 planets,
ranging in mass from Earth’s Moon to
Jupiter, for every main sequence star,
one that’s kinda like the Sun.
Which is so many, but it’s consistent with
theoretical estimates.
And there could be many more.
For one, the data can only reveal rogue planets,
because ones orbiting a star wouldn’t cause
enough of a microlensing effect on their own.
Also, the team was only looking at a small
part of the galaxy.
So there’s plenty of hope for discoveries.
Overall, this isn’t surprising news,
because astronomers totally expect planets
to exist in galaxies other than our own.
But the fact that we can finally say they
are almost certainly there is a huge milestone,
and this opens the door for astronomers to
learn more about these especially alien worlds.
Thanks for watching this episode of
SciShow Space!
If you’d like to keep
learning about the universe with us,
you can go to 
youtube.com/scishowspace and subscribe.
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