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The search for life somewhere else in the Universe has been intensifying
lately. While no conclusive evidence for extraterrestrial life has
yet been found, the search goes on, and it continues to be one of the
most exciting and important topics in astronomy. Some of the major
efforts include the SETI project, the NASA Origins program, searches
for extrasolar planets, and solar system probes.
The Search for Extraterrestrial Intelligence (SETI) is a decades-old,
privately funded program to use radio telescopes to listen for signals
from other technological civilizations in our Galaxy. The SETI program
uses state-of-the-art radio receivers that can monitor one million
radio frequencies simultaneously. They have a very large list of
target stars to monitor, and while they have not yet found a signal
that meets their strict detection criteria, in many ways this search
has just begun. You can find out more about SETI at their website
(http://www.seti.org/).
The NASA Origins program hopes to shed light on the question of life
elsewhere by striving to understand the processes that led to the
development of life on Earth. This wide-ranging program includes such
topics as: galaxy evolution, star and planet formation, biology,
and planetary science. You can find out more about this exciting
program at their website (http://origins.jpl.nasa.gov/).
Astronomers (including some here at Lick Observatory) have recently
been discovering many planets around stars other than the Sun. It is
extremely difficult to detect these planets, and only through a
combination of advanced technology and careful observation can such
measurements be made. Many of the planetary systems have suprising
characteristics, and the sensitivity of our best instruments is not
yet high enough to detect planets as small as Earth. Nevertheless,
the existence and apparent abundance of other planetary systems are
exciting indications that there is nothing particularly special about
our solar system; that the planetary systems necassary for life as we
know it are commonplace and innumerable. Find out more about the
search for extrasolar planets at:
http://www.physics.sfsu.edu/~gmarcy/planetsearch/planetsearch.html
Finally, there are some places in our own solar system that may
currently be, or at least may have been in the past, home to some form
of life. First, there is our neighboring planet Mars. While the
recently reported evidence of microfossils in a Martian meteorite has
been found to be inconclusive, Mars remains a primary candidate for
extraterestrial life. The Mars of today seems pretty inhospitable:
completely devoid of liquid water, almost no atmosphere, and very
cold. However, there is evidence that liquid water once graced its
barren surface, however briefly. Also, the fact that life on Earth
invades every seemingly barren nook and lifeless cranny (including the
Mars-like Antarctic wasteland), gives us circumstantial hope that
Martians may not be just science fiction after all. In addition,
there is speculation that the tidally heated, subsurface ocean of
Jupiter's moon Europa may be a suitable habitiat for living organisms
(although surely vastly different than anything we know of on Earth!)
NASA and other space agancies are sending (or planning to send)
planetary probes to better explore and understand the planets, moons,
comets and asteroids of our solar system. The question of life
elsewhere is certainly one of the reasons for sending these probes.
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