30 | SCIENCE ILLUSTRATED"F
or decades now, we have
been living on the planet
of Nuwa in a small solar
system with seven
rocky planets. On rare
occasions, violent storms blow holes in the
thick cloud cover, which usually shrouds the
world of Shennong. When I was 20 years old,
I came close to the planet, travelling in one
of our spacecraft, and I saw something
incredible through a hole in the clouds. A tall
structure measuring several km, perhaps a
space elevator or an atmospheric power
station. Ever since, I have dreamt of going
to that veiled planet one day. We do not
dare to yet, as we cannot see the surface.
But they are there. Their civilisation isancient and extremely sophisticated. They
must have observed us many years ago, as
we approached the planetary system
aboard our spacecraft.”
The account is pure science fiction,
written by Swiss author Laurence Suhner, but
the text is sensational, as it was published in
one of the world’s leading scientific journals,
Nature, which usually keeps straight to the
facts. But now, imagination is allowed to rule
because of excitement concerning the
discovery of seven Earth-like rocky planets,
which are orbiting a small red dwarf star only
39 light years from Earth. And three of the
planets are even located in the habitable
zone, where water could flow on their
surfaces, so they might include life. Hence,when the discovery was published, Nature
asked the writer to leap 400 years forward in
time, imagining what life would be like in a
colony near one of the planets.ASTRONOMERS HAD 500 HOURS
The dwarf star has been known since 1999,
but did not become really interesting until
last year, when Michaël Gillon and his
colleagues from the University of Liège,
Belgium, aimed the 60 cm Trappist
telescope at the red dwarf. The telescope
is designed to look for exoplanets, which
reveal their existence, when they pass in
front of the star as observed from Earth. As
it passes by the star, the planet reduces
the light of the star, and the telescopePLANET B IS RED-HOT
The planet orbits so close to the star
that it receives four times as much
heat radiation as Earth does.DISTANCE TO THE STAR: 0.011 AU
(the distance from Earth to the Sun )
ORBIT TIME: 1.51 days
MASS: 0.85 Earth masses
RADIUS: 1.09 times Earth's radiusPLANET C LACKS WATER
The next planet is only slightly fur-
ther away from the star, so it is still
much too hot to include water.DISTANCE TO THE STAR:
0.015 AU
ORBIT TIME: 2.42 days
MASS: 1.38 Earth masses
RADIUS: 1.06 times Earth's radiusPLANET D IS ALSO HOT
Though planet d only receives 14 %
more heat than Earth does, it is also
too hot to include liquid water.DISTANCE TO THE STAR:
0.021 AU
ORBIT TIME: 4.05 days
MASS: 0.41 Earth masses
RADIUS: 0.77 times Earth's radiusThree Planets Bask
in the Habitable Zone
TOO HOTTHE RED DWARF IS
NOT VERY BRIGHT
The dwarf star mostly emits
infrared heat radiation and
only a little visible light.AGE: 3-8 billion years
LIFE SPAN: 12 trillion years
MASS: 8% of the Sun's mass
DIAMETER: 11 % of the
Sun's diameter
TEMPERATURE: 2,559 °C
DISTANCE TO EARTH:
Approximately 39 light yearsJPL-CALTECH/NASA
Trappist-1 is only
0.05% as bright as
the Sun, but as
the solar system
is very small,
three of the
planets still
orbit in the
habitable zone.SPACE EXOPLANETS