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Even though it can sound all futuristic and sci-fi,
sometimes, astronomy is just about studying stuff that’s really old.
And the older it is, the cooler it gets.
On Monday, astronomers published a paper in the journal Nature Astronomy announcing that
they’ve found one of the oldest galaxies we’ve ever seen: a galaxy named G09 83808.
Which, somehow, is the shortened version of its name.
It formed 12.8 billion years ago, making it less than a billion years younger
than the universe itself.
It’s what astronomers call a dusty, star-forming galaxy,
or one that produces hundreds of stars each year.
And it’s the third-oldest one we’ve ever found, behind ones that formed
880 and 760 million years after the Big Bang.
The galaxy was first spotted in 2012 by the orbiting Herschel Space Observatory,
but it wasn’t powerful enough to see it clearly.
So the real star of this story is the Large Millimeter Telescope, or LMT, in Mexico,
which started observing the galaxy in 2014.
The LMT was designed to study the farthest, faintest objects in the universe,
including galaxies like this one.
Like other telescopes, it calculates the object’s distance using its redshift,
or how red its light looks because of the universe’s expansion.
See, as the universe expands, the light from distant galaxies gets stretched, too.
That gives the light a longer wavelength, which means that by the time we see it,
it's been shifted toward the redder, longer side of the spectrum.
By measuring how much the light has shifted, whether it’s white light that looks red,
or radio waves with a longer wavelength than normal,
scientists can get a good idea how far away the object is.
Even though telescopes like the LMT are powerful,
they aren’t strong enough to observe galaxies this far away on their own.
To find this one, scientists got a little help.
But it wasn't from another telescope, it was from an effect known as gravitational lensing.
Conveniently, there was another large galaxy between us and 83808.
It was in just the right spot, and was so massive that the light bent around it,
magnifying 83808 and making it look about 10 times brighter than normal.
Studying ancient galaxies like this can teach us more about the timeline of the universe.
Astronomers think galaxies started forming between 200 million and a billion years
after the Big Bang, and because of its age, this discovery supports that idea.
And maybe the coolest part about all of this is that even though the LMT
is helping us make discoveries, it isn’t even at full capacity yet!
At first, it was only about 30 meters in diameter, but now,
it’s fully-built and is 50 meters across, and will be ready for more science this January.
So, pretty soon, we’ll be checking out even more galaxies
from a long, long time ago, far, far away.
Closer to home, another team of astronomers
has developed a new method for finding habitable exoplanets.
And their strategy, published in the journal Scientific Reports last week,
could save astronomers a lot of time.
A habitable exoplanet can refer to a lot of things,
including planets in the right orbit around their stars, or ones with liquid water.
But this method specifically searches for planets with an atmosphere we could breathe.
Normally, scientists hunt for habitable exoplanets by looking for molecules like oxygen and methane,
which are made by plants and animals here on Earth.
Unfortunately, that method can take days of observation,
which isn’t always possible when everyone wants a piece of those fancy space telescopes.
This new method finds habitable planets by searching for the byproducts of stellar storms.
And instead of taking days, it only takes a few hours.
So far, we haven’t tested it out on any exoplanets,
but we know the idea works on Earth.
Plenty of stars, including our sun, have the occasional storm,
where they release high-energy particles into space.
On Earth, you often hear about them causing the northern and southern lights.
But those storms also kickstart a chemical reaction in our atmosphere.
The particles react with the atmosphere’s nitrogen and oxygen to create three molecules:
hydroxyl, or hydrogen and oxygen atoms bonded together; nitric oxide,
which is one nitrogen and oxygen; and plain old molecular oxygen.
These molecules aren’t a definite sign of an Earth-like atmosphere, but they’re so
important that the authors of the paper call them “atmospheric beacons of life.”
And we can detect them with space telescopes.
We’re most familiar with the reaction on Earth, but it isn’t limited to us:
Any planet with a lot of nitrogen and oxygen in its atmosphere
would react this way if it got hit with a stellar storm.
So, if we scan for atmospheric beacons around planets with stormy stars,
we could find habitable planets with an atmosphere like Earth’s.
We’d still be limited to planets we could see directly, but scientists estimate we’d
be able to find beacons with a telescope smaller than the Hubble Space Telescope.
And if we did, we could use newer telescopes, like the James Webb Space Telescope,
which will launch in 2019, to take a closer look at the planets with those beacons.
Researchers are always on the hunt for new, habitable exoplanets,
so this might be the start of an exciting new chapter in astronomy.
Now, those beacon molecules could still exist around a planet without an Earth-like atmosphere,
so we’ll need to be sure we know what else could cause those signals too,
like volcanoes, before we jump to conclusions.
But since this method takes less time, it will let us scan a lot more planets.
So maybe someday, besides having more old galaxies to study,
researchers might also have a whole long list of habitable exoplanets, too.
Thank you for watching this episode of SciShow Space!
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and make it free and available to everyone.
Thank you!
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