On August 19, 1977, Jerry R. Ehman, a professor
at Ohio State University, was sitting at his kitchen table when
he realized that he may have been the first human to have been
contacted by an extra-terrestrial, alien race.
The story behind Ehman's revelation started in 1961
when Frank Drake, a Cornell University astronomer, was looking
for a way to stimulate thinking at an upcoming scientific conference
on intelligent life in outer space. He began to ponder the mathematics
of the problem wondering what the chances were of contacting other
intelligent beings out in space via radio. The result was the
now famous "Drake Equation."
G P E L I C Y
The equation, in theory, estimates the number of
alien civilizations in our galaxy that might produce radio transmissions
we can detect. The G in the formula is the number
of stars in our galaxy, P is the fraction of stars that
have planets, E is the fraction of planets around a star
that can sustain life, L is the fraction of those planets
that actually develop life, I is the fraction that develop
intelligent life, C is the fraction of those that build
civilizations that can communicate and Y is the number
of years that the civilization survives.
From the beginning the formula was controversial
since so many of the figures that go into the equation are unknown
and their values could vary wildly. For example, if the fraction
of worlds on which life develops is sufficiently close to zero,
because it is multiplied against all the other elements, it could
make the number of alien civilizations very small no matter how
large the values all the other variables carry.
Even so, the Drake Equation seemed to suggest that
there would be a number of civilizations in our galaxy that might
be broadcasting radio signals, so the Search for Extra-Terrestrial
Intelligence (SETI), which Drake had founded the year before,
started to expand.
In 1960 Drake had done his initial research using
a 26-meter radio telescope dish at Green Bank, West Virginia.
He pointed the telescope towards the stars Tau Ceti and Epsilon
Eridani and looked for any broadcast signals near the 1.420 gigahertz
radio frequency. Drake thought it likely that any alien civilization
trying to make its presence known would broadcast a signal near
that frequency because the hydrogen spectral line was located
there and hydrogen was the most abundant element in the universe.
radio telescope at Green Bank, West Virginia where Drake
conducted his first SETI search in 1960. (NRAO/AUI
licensed under the Creative Commons Attribution-Share Alike
Drake failed to find any interesting signals, but
other scientists thought that the search was worthwhile and started
projects to scan the skies. In the 60's scientists from the Soviet
Union became interested in SETI and conducted several searches.
Back in the United States, Ohio University had constructed a radio
telescope called the "Big Ear" in 1963. The device had been used
for several scientific research projects, including a study of
the Andromeda Galaxy. In 1973, however, Bob Dixon, on staff at
Ohio, realized that idle time on the telescope might be used for
SETI research and organized some volunteers to help. The program
ran from 1975 to 1983.
The "Big Ear" was unlikeradio telescopes that most
people might picture in their mind. It wasn't shaped like a big
dish as the one at Green Bank that Drake had used. A dish like
that could be pointed to any location in the sky. Instead the
"Big Ear" was composed of a flat signal reflector 340 feet wide
and 100 feet high. This flat reflector could be tilted up and
down 50 degrees to point at almost any vertical (up and down)
location above the horizon. The radio waves coming from the sky
would bounce off the flat reflector and over to a parabolic reflector
360 feet wide and 70 feet high that was 500 feet away. The parabolic
reflector would then concentrate the signal to a location on the
ground just in front of the flat reflector where two "horns" were
located. The horns would further concentrate the signal and pass
it to a receiver where it would be converted to electrical impulses.
These would then be analyzed by a computer.
The weakness of the "Big Ear" was that though it
could be pointed to a wide area of the sky up and down, it could
not be swung left or right. In order to observe those areas, it
had to wait until that section of the sky was brought in front
of it by the rotation of the earth. Then it could observe that
location for up to 72 seconds. The strength of the "Big Ear" was
that even though it could not be pointed in arbitrary directions
because of its enormous size, it was sensitive to very weak signals.
Two years into the "Big Ear's" SETI program came
the incident that still puzzles scientists to this day. On August
15, 1977, at 10:16 PM EST, a computer running the SETI program
that controlled the telescope recorded a signal coming from space.
Nobody was at the telescope at the time and the computer, as it
always did recorded the characteristics of the signal automatically.
Later information about the signal was printed onto a paper listing
so it (along with everything else recorded by the computer) could
be reviewed by a human being.
Now, getting a radio signal from a source in space
wasn't that strange at all. That's what the "Big Ear" was built
for. Most sources are from natural celestial objects including
pulsars (rapidly rotating burned out stars) or quasars (distant,
bright galaxies). What made this signal different and caught the
attention of Jerry Ehman, when he reviewed the printout several
days later, was the shape and the strength.
Most natural signal sources come in a very wide
band involving many adjacent radio frequencies. Artificial, man-made
sources, however, are almost always narrow-band involving just
a few frequencies.
signal that Ehman noticed was very narrow and strong. What's more,
it lasted almost exactly 72 seconds. This was significant as that
was the amount of time the "Big Ear" was able to detect a signal
from deep space as its observation zone swept the sky. The way
the signal started, became strong, and then dropped away over
that period was exactly what would be expected from a deep space
signal heard by the "Big Ear." Ehman was so impressed by the signal
being exactly what was expected of an alien contact that he circled
it on the paper and wrote the word "Wow!" next to it in red ink.
The incident has been known as the "Wow!" signal ever since.
One common misconception is that "Wow!" was the
content of the signal, but it was only Ehman's reaction to it.
Another is that the content of the signal was the number/letters
Ehman circled on the paper. Those are only the way the computer
represented the strength of the signal. The content of it, if
there was any, was not recorded by the computer and is unknown.
Ehman and others have searched for explanations
of the signal beyond an intelligent, extra-terrestrial source,
but so far nothing seems to fit the bill.
One early thought was that it was a terrestrial
radio signal bouncing off a piece of space junk. However, the
frequency that the signal came in on was approximately 1420 MHz.,
very near the frequency emitted by hydrogen atoms. This frequency
is reserved for astronomical observations and no transmitter on
Earth should be using it. Also, the signal's expected characteristics,
if it had been bounced off a piece of space junk in Earth's orbit,
did not completely match that of the "WOW" signal. A piece of
space junk in low orbit would be moving, changing the length of
the signal. It would also be tumbling, which would change the
amplitude of the signal so it did not grow and fall in a nice,
though the "Big Ear" telescope is no longer with
us, SETI programs continue to scan space from telescopes
like the Arecibo in Puerto Rico.
Other possibilities of the source of the signal
that have been eliminated were satellites, airplanes and spacecraft.
No known satellite or spacecraft was in the right position and
none should have been transmitting near 1420 MHz. Airplanes would
have been moving and would have changed the observation time,
and again, none should have been transmitting at 1420 MHz.
The area that the "Big Ear" was pointing at when
it detected the "Wow!" signal was northwest of the globular cluster
M55. There are no close stars in that area that might seem to
be the source of an extra-terrestrial signal. The "Big Ear" listened
for a return of the signal on subsequent occasions, but it was
never heard again. In fact the "Big Ear" had two horns which swept
the sky that day about 5 minutes apart.The signal was heard by
only one of the horns, not both, so it seems that the signal was
either switched off or directed to a different location during
those five minutes.
Many radio telescopes have listened for a signal
in that location since then, but have found nothing. What does
this mean? Scientists connected with the project think that even
though it looked like an alien signal, without being able to detect
it again and study it, there is no way to ever know for sure.
Ehman himself cautions against making "vast conclusions from 'half-vast'
So the "Wow!" signal remains a true modern mystery.
Was ET trying to talk to us and if he was, will he phone again?
Copyright Lee Krystek
2015. All Rights Reserved.