Hubble spots liquid water on a ‘super-Earth’ 110 light-years away

Water is not uncommon to find in our galaxy in ice or gaseous
form, but liquid water is quite rare — and liquid and gaseous
water on an Earth-like exoplanet? That’s never been observed…

until now
. Astronomers spotted this celestial unicorn, called
K2-18 b, using the venerable Hubble space telescope.

K2-18 b is a “super-Earth,” a planet with a mass and size
approximately like our own, and not only that, it exists in its
solar system’s “habitable zone,” meaning a range of
temperatures where liquid water can continuously exist. It’s
about 110 light-years away in the constellation Leo.

Of course there are many super-Earths, and many planets in
habitable zones, and many planets with water — but they’re
never one and the same. This is the first time we’ve found the
trifecta.

Researchers used past Hubble data to examine the spectral
signature of light shining from K2-18 b’s sun through its
atmosphere. They found evidence of both liquid and gaseous water,
suggesting a water cycle like our own: evaporation, condensation,
and all that.

To be clear, this is not an indication of little green men or
anything like that; K2-18 b’s red dwarf sun is absolutely
bombarding it with radiation. “It is highly unlikely that this
world is habitable in any way that we understand based on life as
we know it,” the Space
Telescope Science Institute’s Hannah Wakeford told
Nature
.

Too bad — but that wasn’t what scientists were hoping to
find. The discovery of an Earth-like planet with an Earth-like
water cycle in the habitable zone is amazing, especially
considering the relatively small number of exoplanets that have
been examined this way. The galaxy is full of them, after all, so
finding one with these qualities suggests there are plenty more
where K2-18 b came from.

This discovery is an interesting one in another fashion: It was
done, like lots of others are these days, by performing
after-the-fact analysis on publicly available data (from 2016 and
2017), and the analysis used open-source algorithms. Essentially
both the data and the methods were out there in the open — though
naturally it takes serious scientific effort to actually put them
together.

Two papers were published on K2-18 b, one from the University of
Montreal and one from University College London. The former
appeared on preprint
site Arxiv
yesterday, and the other was published in
the journal Nature Astronomy today
.

Source: FS – All Tech News 2
Hubble spots liquid water on a ‘super-Earth’ 110 light-years away