- 4332 - PLANETS - that may support life? James Webb Space Telescope recently found traces of methane and carbon dioxide in the atmosphere of exoplanet “K2-18-b”, an exoplanet 8.6 times as massive as Earth about 120 light-years from us. The signature may be a sign of a water ocean.
------------------------- 4332 - PLANETS - that may support life?
- Searching for liquid water on exoplanets is
the key to finding life among the stars.
Researchers have hypothesized that if the atmosphere of an exoplanet has
less CO2 than its neighbors, there may be vast quantities of water on its
surface, or even life.
-
- Finding liquid water on planets outside the
solar system is a major challenge. Of the 5,000 or so exoplanets we've
discovered, liquid water hasn't been
confirmed on any. The best scientists can do is detect traces of water in
exoplanet atmospheres and determine whether planets could theoretically support
water in the liquid state.
-
- We know that initially, the Earth's
atmosphere used to be mostly CO2, but then the carbon dissolved into the ocean
and made the planet able to support life for the last four billion years.
-
- Once carbon is dissolved in the oceans,
tectonic activity then locks it away in Earth's crust, creating an effective
carbon sink. This is partly why our planet has significantly lower CO2 levels
compared with our neighbors. Earth's
atmosphere is around 0.04% CO2, whereas the atmospheres on Venus and Mars are
both over 95% CO2.
-
- If scientists observe a similarly low-carbon
atmosphere on an exoplanet, it could indicate the presence of vast oceans
similar to our own. Looking for CO2 is
easier than finding liquid water. CO2 absorbs infrared radiation very well,
meaning it produces a strong signal that scientists can detect.
-
- It's also possible to perform this technique
with existing telescopes, such as the James Webb Space Telescope (JWST).
Ground-based observations should also be possible because of the specific
wavelength CO2 is measured at whereas Earth's atmosphere can torpedo
experiments at other wavelengths by partially absorbing the signals.
-
- Another scenario could contribute to an
atmosphere low in carbon: life itself. The main ways life on our planet
captures carbon are through photosynthesis and making shells, and around 20% of
all carbon capture on Earth is caused by biological processes.
-
- JWST found the unambiguous signature of
water on exoplanet “WASP-96B”. A new technique may make it even easier for
telescopes like JWST to find water.
-
- As researchers keep discovering more
exoplanets, more atmospheres will also be spotted. And this technique could
help figure out whether they could sustain life.
-
- Another scenario could contribute to an
atmosphere low in carbon: life itself. The main ways life on our planet
captures carbon are through photosynthesis and making shells, and around 20% of
all carbon capture on Earth is caused by biological processes.
-
- Although the approach looks like it'll work
in principle, there may still be hurdles, as it's not clear how many
terrestrial exoplanets also have atmospheres. Finding the perfect system to
test this on might turn out to be a little bit more challenging than we
previously thought.
-
-
January 28, 2023 PLANETS -
that may support life? 4332
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--------------------- --- Monday, January 29,
2024
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