SETI: The Search for Extraterrestrial Intelligence


Are we alone? Since we became aware of the vastness of the universe, this question has intrigued and bewildered us. A question that has led us to explore the furthest depths of the universe. And yet, we don’t have a correct answer.

SETI: The Search for Extraterrestrial Intelligence is the term used for the search for answers to this big question. The sole purpose of SETI has been to find the existence of other lives in the universe which is done by examining radio waves, electromagnetic radiation and much more, as well as transmitting our own messages in the hope that one day we might receive a response. 

Scientists estimate that our universe consists of more than one hundred billion planets that could possibly have life. This amount is tough for the human mind to comprehend even while gazing out on a stary night, and the fact that the universe is probably in the region of 100 billion light-years in diameter when one light-year is equivalent to 9.5 trillion km is overwhelming.

In light of such mind-boggling sizes, it’s not hard to understand why so much time and effort have been devoted to searching for extraterrestrial life.

Historical Background of SETI

An early view of the Ohio State University Radio Observatory known as Big Ear
Figure 1: An early view of the Ohio State University Radio Observatory known as Big Ear

During the late 20th century, to detect another life in our universe, scientists converged upon the basic idea of scanning the sky and “listening” for non-random patterns of electromagnetic emissions such as radio or television waves.

And at first, the scientists were focused on Mars as it is the most similar planet to planet earth within our solar system. Between 21st and 23rd August 1924, Mars travelled closer to Earth for the first time in the century which would not happen again for the next 80 years. An excited buzz rippled across not only scientists but also the whole of America as a National Radio Silence day was prompted encouraging people to turn off their radios for five minutes for each hour. Meanwhile, a huge radio receiver attached to an airship was lifted 3 kilometres (1.9 miles) above the United States Naval Observatory in Arizona, where it waited expectantly.

In late 1959 and early 1960, the modern SETI era began when Frank Drake conducted the Project Ozma in conjunction with Cornell University which was the first time distant planetary systems had been studied through interstellar radio waves.

And in 1960 the Soviets started numerous searches using omnidirectional antennas in the hope of picking up a signal.

Beginning in 1963, Ohio State University established the first formal, continuous SETI program. A radio telescope named Big Ear measured 103 meters by 33 meters and cost $71,000 in grants from the National Science Foundation.

A Glimmer of Hope

The Big Ear brought hope! A signal named WOW was observed from the Big Ear telescope. It was the first and last time since now, Earth received an extraordinary radio signal from the universe.

The Wow! Signal from 1977, as discovered by astronomer Jerry R. Ehman
Figure 2: The Wow! Signal from 1977, as discovered by astronomer Jerry R. Ehman

The signal came in a 6-digit form and lasted for 72 seconds that Big Ear was capable of observing. It was discovered by the astronomer Jerry R. Ehman and he scribbled WOW!, next to it on the page, thus the name WOW.

Present Situation and Future Prospects

The latest approach to this Search for Extra-Terrestrial Intelligence in the universe is called METI which is Messaging to Extra-Terrestrial Intelligence which is a little controversial because we don’t know what to expect from out there and if we just shout out we are here to the universe, there’s a possibility of a bunch of aliens coming to attack us. But anyway scientists have sent out 19 messages so far to the universe in the hope of receiving a reply.

A recent development has been the search for techno signatures which are signs of life such as city lights on planets, space mirrors, atmospheric contamination, space crafts etc. This is done by monitoring the light, heat and chemicals emitted by planets using infrared telescopes, satellites, or gamma-ray observatories.

Over the last few decades, the debate over extraterrestrial life has progressed far beyond the simple question of whether or not they exist. And with the continued failure to find anything concrete, it has led many to question is it possible that one or more civilizations have already perished? So it can be a matter of the right place at the wrong time. Nevertheless, with the rapidly developing technologies, I believe we are getting closer and closer to discovering extraterrestrial life in the universe.


  1. Shostak, S. (2017, June 17). Was it ET on the line? Or just a comet?
  2. Wenz, J. (2017, June 8). Aliens, Comets or Crap? What’s Going On With The Wow! Signal?
  3. Shostak, S. (2021, July). A Primer on SETI at the SETI Institute.

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