The
team searching for signals from intelligent civilizations among the stars at
the SETI Institute recently turned its radio telescopes to a mysterious star whose
light output varies in an unusual way.
Called by its catalog number KIC 8462852, the star is about 1500 lightyears away in
the constellation of Cygnus the Swan. Observations with the Kepler space
telescope had shown that the star’s brightness dipped at irregular intervals
and with irregular amounts of darkening.
Such dips are how the
Kepler telescope finds planets orbiting distant stars. Astronomers photograph huge numbers of stars
regularly, and search for regular dips in a star’s light when a planet
gets in front of the star, reducing its brightness. A planet circles its star regularly, and the
dips in brightness come on a clockwork schedule. If the planet takes 100 days to orbit its
star, astronomers would see a dip in brightness every 100 days – just while the
planet is in front of its star. Here is
a little animation to show you the idea: https://www.youtube.com/watch?v=pf9PjFQIpzU
But KIC 8462852’s dips in brightness are not
regular at all and they vary in how much of the star’s light they block. One such dip in brightness took away more
than 20% of the star’s light, indicating that whatever was causing it must be
much bigger than a planet. What could be
causing such unpredictable and large dips?
It could, for example, be a huge swarm of comets that orbit the star in
different clumps. It could be great
clouds of dust from deep space which the star happens to be moving
through. But there is another
possibility, which got some astronomers and all science fiction fans excited.
What if there is an
advanced civilization around that star, far beyond our own in technology? One thing such a civilization is likely to
need is huge amounts of energy to carry out their projects. An easy way to get that is to build huge “solar
panels” orbiting their star.
Alternatively, perhaps they are building giant space habitats to house
their excess population.
Just like our cities are
irregularly spaced and irregular in terms of internal construction, so these
space construction projects could be different in size and spacing, causing the
irregular dips we see as they move in front of their star. While the explanation is most likely
something natural in the universe, it’s fun to consider a cause that could be a
signal for the existence of intelligent life.
The leading
organization in the search for life beyond Earth is the SETI Institute (where I
have the privilege of serving on the Board of Trustees.) They have an instrument, called the Allen
Telescope Array (ATA), with 42 coordinated radio telescopes in Northern
California, specifically designed to find intelligent radio or microwave
signals from the stars.
For more than two
weeks, the Institute team, led by Dr. Seth Shostak, trained the ATA on KIC 8462852, to see if any pattern of
signals might be leaking from such an advanced civilization. At a distance of 1500 lightyears (where each
lightyear is 6,000 billion miles), the alien transmissions would have to be
awfully strong to be detectable from Earth.
Still, a civilization able to build huge space structures might have
powerful beacons to communicate with its own outposts, and we might be able to
eavesdrop on one of their messages pointed our way.
So far, in the channels
the Institute team searched, no intelligent signal was detectable. They also searched for a much broader beam of
microwaves, which advanced aliens might use to push giant ships through
space. No such beam was found either.
But what exciting ideas
such observations bring to our minds!
The possibility of detecting some kind of intelligent species that is
out there in the Galaxy has intrigued humanity for centuries. Today, for the first time, we actually have
the technology to do experiments in this area. I’d love to see us find evidence that we have “cousins”
among the stars. This is why I have
served on the SETI Board for many years now.
The Institute also does other
wonderful research, in many areas of astronomy and planetary science. (One of our scientists, Mark Showalter, found
two of the small moons of Pluto, for example.)
There is also great work going on in education and public outreach,
including the syndicated “Big Picture Science” radio show that Seth Shostak
co-hosts.
December 1 is “Giving
Tuesday” – a day designed for all of us to pause after the shopping frenzy that
follows Thanksgiving, and consider giving to non-profit organizations whose
work we believe in. Perhaps you’d like
to join me in supporting the SETI Institute.
For ways you can help, see their website at: http://www.seti.org/supportus
(NOTE: The photo shows a few of the radio telescopes that make up the Allen Telescope Array.)
And KIC stands for Kepler Input Catalog.
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