00:00A new super-Earth has been spotted by astronomers, and it's quite intriguing.
00:05This planet, called TOI-715b, is about one and a half the size of Earth,
00:11which is why it's called the super-Earth.
00:13It's also relatively close to us in space terms, only 137 light-years away.
00:19For comparison, most exoplanets are hundreds of light-years away.
00:24And all the interesting stuff, like black holes and nebulas,
00:27are usually more than thousands of light-years away from us.
00:30So, could it be habitable?
00:34The habitable zone is an estimate of where a planet might have the right conditions for liquid water.
00:41This is what we call some distance from the star,
00:43where the temperatures on the planet should be okay-ish,
00:47and water should stay liquid on its surface.
00:49It's not super precise, because it depends on a bunch of factors,
00:53like the type of star, how reflective the planet is, its size, and so on.
00:59Also, just being in this zone isn't enough for water to actually be there.
01:03The planet also needs the right kind of atmosphere, and a few other things.
01:08So, we invented a stricter definition in 2014, the conservative habitable zone.
01:14It's a more precise term defining the best candidates that have liquid water.
01:18Otherwise, we get too many potentially habitable planets that are not actually habitable at all.
01:25The CHZ is based on how much energy a planet gets from its star compared to Earth.
01:31If a rocky planet gets between 40 to 85%,
01:35it's considered to be in the CHZ, no matter how far away it is from its star.
01:40These planets have a higher chance of being habitable.
01:43And yes, TOI-715b is located there.
01:51This super-Earth orbits the M-type star, also called Red Dwarf.
01:56It's a star that's much smaller and cooler than our Sun, about a quarter of the Sun's size and mass.
02:02But if the planet is located in the habitable zone, it's actually a better option for life.
02:08Red Dwarfs live much longer than our Sun, a yellow dwarf.
02:11This also means that they have more time to form little creatures on their planets.
02:16And this red dwarf really is older than our star.
02:19Our Sun is 4.6 billion years old, and this star is 6.6 billion years old, give or take a few hundred million.
02:28It doesn't have much magnetic activity, so it's not dangerous.
02:32It doesn't flare up like younger red dwarfs.
02:35These flares can be super strong and might even hurt planets by taking away their atmospheres.
02:39Although some planets around it do have thinner atmospheres, it seems like this red dwarf has already gone all out.
02:48These red dwarfs are where we're looking for planets that could support life right now.
02:53Our super-Earth is really close to its star, zooming around it in just 19 days.
02:58Since the star is small and the planet is so close, the planet passing in front of its star happens a lot and looks really clear.
03:07This makes it easy for telescopes like the James Webb to study its atmosphere without needing too much time.
03:13Now, speaking of the James Webb Space Telescope, it's bringing us into a new era of understanding distant planets beyond our solar system.
03:23Imagine being able to see what gases make up the air on a planet millions of light-years away.
03:29James Webb will help us to find worlds that could support life.
03:33Right now, it's trying to figure out whether TOI-715b has an atmosphere.
03:39If it does, its atmosphere might be easier to spot compared to a planet that's drier and denser.
03:45And then, we might get even more height because it would look like a good place for life.
03:51On top of all that, there might be another planet in this system, also in the habitable zone.
03:56We're not sure whether it's really there, it's just a candidate with a crazy name.
04:02But if it turns out to be real, it would be about the size of Earth.
04:06Also, it would be the smallest planet in the habitable zone ever spotted by the TESS telescope.
04:13Now, another cool thing about TOI-715b is that it cannot just have water on it, but be an entire water world.
04:22An ocean planet is a type of planet that has an ocean covering its surface or has subsurface oceans.
04:29They might not have much dry land because the water can cover everything.
04:33Sometimes, the entire planet can be covered in other liquids, like lava or ammonia.
04:38When it comes to planets outside our solar system, we can't see surface water directly with our current technology.
04:45Instead, scientists look for water vapor in the atmosphere as a hint there might be liquid water below.
04:51And, of course, we wonder if these planets can have life, hopefully not in the form of leviathan-like monsters.
04:59Our models show that planets with oceans might be pretty common in our galaxy.
05:04This means there could be lots of ocean worlds out there waiting to be discovered.
05:08But the most important part about TOI-715b is that it's in the so-called small planet radius gap.
05:20If we give the planets a lineup, there will be those that are bigger and smaller than Earth.
05:25But there's a sudden gap in planets that are about from 1.5 to 2 times bigger than ours.
05:31Where are they?
05:32This gap is interesting to scientists because it tells us something about how planets form and change over time.
05:39It's not that planets don't form in this size range.
05:42They actually start off larger and then lose some of their mass, like a balloon gradually deflating.
05:48Perhaps it happens because of how they orbit their stars,
05:51with stars blowing away some of their mass as they dance around it, as our Sun does with gas from comet tails.
05:58This gap holds a lot of mystery.
06:01And planets, like our new super-Earth, are clues that could help us unravel it.
06:06We aren't sure whether it exists around red dwarfs.
06:09Maybe it's a gap in how dense these planets are, rather than in their actual size.
06:14So studying our discovered planet is even more interesting.
06:18It'll help us learn more about distant stars and their planets.
06:21Now, I mentioned TESS a while back.
06:25NASA's TESS, Transiting Exoplanet Survey Satellite, has been in space for six years now and has been incredibly successful.
06:34NASA launched TESS because we already found over 5,000 planets orbiting other stars, mainly thanks to the Kepler telescope.
06:43But Kepler mostly found large planets, not necessarily like Earth.
06:47We decided to focus TESS on finding smaller Earth-like planets around nearby bright stars, making them easier to study with future telescopes.
06:59Here's how it works.
07:00The camera observes stars and looks for changes in their brightness.
07:04If the brightness suddenly drops for a while and then gets back, it could mean there is a planet passing in front of it.
07:11But stars can dim for other reasons, too.
07:13For example, flaring up or having dark spots on their surface, which is why we need to be careful with this data.
07:21TESS shows us the size and orbit of these planets.
07:24Then, ground telescopes help determine their mass.
07:28With these three parameters, we can figure out what the planets are made of and if they're rocky like Earth or gassy like Jupiter.
07:35Yeah, you want to avoid Jupiter after taco night.
07:38One example of TESS's discoveries was the TOI-700 system.
07:46There, it discovered its first-ever Earth-like planet, TOI-700d.
07:51This exoplanet also orbited a red dwarf, and it's even closer to us, about 100 light-years away.
07:58Unfortunately, it's unlikely to be habitable because the temperatures there are crazy.
08:03Another big discovery was made in the AU microscopy system.
08:08TESS discovered a planet about four times the size of Earth and another, nearly three times Earth's size.
08:15This system has become a key area for studying how stars and planets form and change over time.
08:21TESS has also spotted a variety of other exciting finds, including supernova, hot worlds, and so on.
08:27And as it enters its sixth year, we can only expect more exciting findings to come.
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