- 4541 -
HABITABLE PLANETS -
getting closer to a find? - The search for habitability elsewhere in
the universe can be reduced to the search for water. We haven't yet found
lifeforms that detach this substance from our conception of "life"
itself, so we have no choice but to accept the water trail as our north star in
the quest to find worlds that mirror our own.
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-------------------------- 4541
- HABITABLE PLANETS
- getting closer to a find?
-
- Researchers just announced that a
tantalizing planet outside the solar system may have a temperate water ocean
about half the size of the Atlantic.
Of all currently known temperate exoplanets, “LHS 1140 b” could well be
our best bet to one day indirectly confirm liquid water on the surface of an
alien world beyond our solar system.
This would be a major milestone in the search for potentially habitable
exoplanets.
-
- “LHS 1140 b” exoplanet orbits a red dwarf
star about a fifth the size of the sun and sits 48 light-years away from Earth
in the constellation Cetus which, as luck would have it, translates to
"the whale." But most important about LHS 1140 b is the fact that it
lives in its star's habitable zone, otherwise known as its "Goldilocks
zone."
-
- As that nickname would suggest, this is the
area around a star where it's neither too hot nor too cold for a world to host
liquid water, but rather fits the standard by which the fairy tale character
Goldilocks lives.
-
- This is the first time we have ever seen a
hint of an atmosphere on a habitable zone rocky or ice-rich exoplane with the
analysis of LHS 1140 b's atmosphere. The
team might have even found evidence of "air" on it.
-
- The exoplanet could be either rocky or
icy. Though it has been making
headlines now due to the new study involving JWST data, LHS 1140 b has actually
been on planetary hunters' radars for some time. In fact, experts had already
theorized that this could be a water world in the past, and even shared similar
sentiments about how it could offer humanity the first-ever direct evidence of
exoplanetary liquid water.
-
- There was something like a gap in the
literature about LHS 1140 b. Basically, the trouble was that scientists
couldn't quite confirm whether the exoplanet is a mini-Neptune — a planet less
massive than our original Neptune, but one that still has Neptunian
characteristics — or a super Earth. A super Earth is a world that's larger than
Earth, but still either rocky or water-rich. -
- This work not only "strongly
excluded" the mini-Neptune scenario, but also confirmed the world may have
a nitrogen-laced atmosphere like Earth does.
The presence of a nitrogen-rich atmosphere would suggest the planet has
retained a substantial atmosphere, creating conditions that might support
liquid water.
-
- There are also a variety of other
habitable-zone exoplanets scientists are drawn to. The most obvious are
probably the seven worlds of the TRAPPIST-1 system, a planetary lineup that
looks almost disturbingly similar to our solar system's structure.
-
- However, a very interesting JWST study
actually complicated the search for habitability in TRAPPIST-1 quite recently.
It revealed that the system's anchor star is incredibly active in such a way
that it could skew our observations, making us believe a world in the system is
habitable when it really isn't.
-
- The star LHS 1140 appears to be calmer and
less active, making it significantly less challenging to disentangle LHS 1140
b's atmosphere from stellar signals caused by starspots. The JWST data further
suggests the exoplanet's mass might be made of between 10 percent and 20
percent liquid water, and, it paints a fantastical picture of what the planet
might look like in simple terms.
-
- It could look like a snowball,
essentially, that orbits its star while rotating in such a way that one side
always faces that star. It's like the moon's orbit around Earth; we can't ever
see the far side of the moon because the moon rotates at the same rate it
revolves around Earth. One side never faces us, and the other always does.
-
- Similarly, this would mean that, if the
JWST's illustration of the LHS 1140 b scene is correct, the side of the planet
always facing its sun would be exposed to lots of heat. This would be the part
of the snowball that's "melted" into a liquid ocean.
-
- Current models indicate that if LHS 1140 b
has an Earth-like atmosphere, it would be a snowball planet with a bull's-eye
ocean about 2,485 miles in diameter. The
surface temperature of the ocean may very well even be a "comfortable" 68 degrees
Fahrenheit.
-
-
August 21, 2024 HABITABLE PLANETS
- getting closer to a find? 4541
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--------------------- --- Tuesday, August 20,
2024
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