This is Exoplanet Radio, I'm Tony Darnell.
The James Webb Space Telescope has completed
observations of an exoplanet that may contain
an ocean-covered surface underneath a hydrogen-rich atmosphere.
This discovery provides a fascinating
glimpse into a planet unlike anything in our solar
system and raises interesting prospects
about potentially habitable worlds elsewhere in
the galaxy.
The exoplanet is called K2-18b and is
located about 120 light-years away from us in the
constellation Leo.
It is bigger than Earth, but not as big as
Neptune, putting this exoplanet in a class
called sub-Neptunes, one of the most common types of exoplanets we've found.
It orbits a cool dwarf star called K2-18 in the habitable zone.
But what's really amazing is that Webb has
detected methane and carbon dioxide in its
atmosphere.
These are carbon-bearing molecules that
could indicate the presence of life, or at least
some interesting chemistry.
Webb used its near-infrared spectrograph,
or near-spec, instrument to analyze the light
coming from K2-18b as it passed in front of its star.
By looking at how the starlight changed as
it filtered through the planet's atmosphere,
Webb could measure the amounts of different molecules in the air.
This technique is called transit spectroscopy
and is one of the best ways to study exoplanet
atmospheres.
The results showed that K2-18b has a
hydrogen-rich atmosphere with traces of methane and carbon
dioxide.
There was also a possible detection of
another molecule, dimethylsulfide, or DMS, which,
on Earth, is only produced by living organisms.
DMS is emitted by phytoplankton in the
oceans and it helps form clouds and regulate the
climate.
Could K2-18b have some kind of ocean life that produces DMS?
Or is there another explanation for this mysterious molecule?
The discovery of methane and carbon
dioxide in K2-18b's atmosphere is consistent with
the idea that this planet could be a "Hycean world."
Hycean worlds are a class of exoplanets that
have hydrogen-rich atmospheres and water-covered
surfaces.
They are different from Earth-like worlds,
which have nitrogen-rich atmospheres and rocky
surfaces.
Hycean worlds could be promising targets
for finding signs of life, but we shouldn't
get too excited just yet.
While K2-18b lies in the habitable zone and is
now known to harbor carbon-bearing molecules,
it does not necessarily mean that the planet can support life.
The planet's large size, it has a radius
2.5 times out of Earth and almost 9 times its
mass, means that the planet's interior likely
contains a large mantle of high-pressure ice,
like Neptune, but with a thinner, hydrogen-rich atmosphere and an ocean surface.
Hycean worlds are predicted to have oceans of wat er.
However, it is also possible that the ocean
is too hot to be habitable or even be in a
liquid state.
Of course, there are still many uncertainties and challenges in studying K2-18b.
Webb's observations are only the first step
in exploring this fascinating world, and more
data and analysis are needed to confirm and refine the results.
These are planning follow-up studies using
the Mid-Infrared Instrument Spectrograph on
JWST that they hope will further validate
their findings and provide new insights into
the environmental conditions on K2-18b.
These exciting results are the product of just two observations, and there are many
more on the way.
We will use the most advanced observatories
on Earth and in space to study this planet
in more detail.
Our ultimate goal is to find exoplanet with life on it.
If such a world exists, and we can find it,
we will have left the cosmic shores of our
home and waded just a bit deeper into the universal ocean and found that we are not
alone.
And maybe, just maybe, we learn that the universe is teeming with life.
Exoplanet Radio is produced by Deep
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