The results of the Pale Red Dot campaign
— the quest to find a planet
orbiting the closest star to the Solar System —
have now been announced.
Astronomers have found clear evidence
of a planet orbiting the star Proxima Centauri.
This alien world is the closest possible abode
for life outside the Solar System!
This is the ESOcast!
Cutting edge science and life behind the scenes at ESO,
the European Southern Observatory.
The search for other worlds has captivated
imaginations throughout history,
but only recently have we had the instruments
able to detect worlds outside the Solar System.
These extrasolar planets, or exoplanets,
went undetected until 25 years ago.
Today, thanks to advances in telescope technology,
astronomers have detected over three thousand.
And now the scientists behind
the Pale Red Dot campaign
have made a milestone discovery.
They have discovered clear evidence for
a potentially habitable planet orbiting Proxima Centauri,
the closest star to the Solar System.
Using the HARPS spectrograph
on ESO’s 3.6 metre telescope at La Silla in Chile,
astronomers spent the first half of 2016 looking
for the tiny back and forth wobble of the star
caused by the gravitational pull of an orbiting planet.
They were trying to build on 16 years
of earlier observations
that hinted of the presence of a planet,
but were inconclusive.
Combining the data with observations
from a network of telescopes around the world,
the researchers confirmed
the detection of an alien world.
It’s at least 1.3 times as massive as the Earth
and orbits Proxima Centauri every 11.2 days.
It was no easy task to identify the planet, however.
Red dwarfs like Proxima Centauri
are active stars prone to flares,
and can vary in ways that would
mimic the presence of a planet.
To exclude this possibility,
the team carefully monitored the brightness of the star
with a network of telescopes
to ensure they didn’t misidentify such an important discovery.
Perhaps the most exciting aspect of this research
is that the exoplanet, called Proxima b,
orbits within the habitable zone of its star.
This means that liquid water could exist
on the planet’s surface.
If it were much closer the heat from the star
would boil the water away.
And if it were further out
the planet’s water would freeze solid.
Since liquid water is essential for life as we know it,
this makes Proxima b the closest exoplanet
to Earth that may harbour life.
However, the same stellar activity that made Proxima b
so difficult to spot
could also make it an inhospitable abode for life —
the planet’s surface is bathed
by intense ultraviolet and X-ray radiation.
The planet also orbits
Proxima Centauri extremely closely,
only 5% of the Earth Sun distance.
It is still a matter of debate whether a planet
so close to its star could support life.
Proxima b’s closeness to the Earth
makes it an intriguing target
in the search for extraterrestrial life.
Astronomers will use the next generation
of telescopes
such as ESO’s European Extremely Large Telescope
to make an intensive study
of this fascinating alien world
in the hope of finding evidence of life
elsewhere in the Universe.
And if interstellar probes become a reality
Proxima b may be their first destination.
Scientific knowledge of exoplanets has grown
has grown hugely in the last 25 years.
With this discovery,
and armed with ESO’s next generation telescope,
we may soon be within reach
of answering the age old question —
are we alone?
Transcription by ESO; translation by —