Introduction
Just as life started on our planet billions of years ago, it may well also have begun on an alien world. Evidence has already been found for extrasolar planets around the closest stars, and there are even suggestions of life on other worlds in the solar system itself. All these details have made scientists more and more optimistic that life exists somewhere else in space.
How likely is life?
The astronomer Frank Drake was one of the first to assess the probability of intelligent life elsewhere in the universe. He tried to estimate the number of civilisations in the galaxy with the means of communicating with us right now. He claimed that for intelligent life to arise on a planet, and to be able to communicate over long distances, conditions on the planet must be just right. His equation took into consideration a number of factors:
N=R*fp ne fl fi fc L
N= the number of civilisations with the ability to communicate over long distances.
R*= the rate of formation of suitable stars
fp= the fraction of those stars with the planets
ne= the number of Earth like worlds in a planetary system
fl= the fraction of Earth like worlds in which life develops
fi= the fraction of life forms that develops intelligence
fc= the fraction of intelligent life forms that develops electromagnetic communication technology
L= the lifetime of these communicating civilisations
Radio telescopes
The question "Is there anybody out there?" has been of great importance to humankind ever since we realised there were other suns in the sky, many with planets in orbit around them. But only within the last fifty years has technology advanced to the stage where we can begin to look for extrasolar life. Frank Drake realized that the most effective way to communicate with extrasolar civilisations was by using radio telescoped. These telescopes are positioned all over the world and can listen for any signals from space that may have been made by other life forms.
Arecibo
In 1974, a message was beamed into space from the Arecibo radio telescope in Puerto Rico. It was made up of 1,6799 pulses which, when arranged into a grid 23 columns wide and 73 rows tall, create an image. This image contains information about life on planet Earth. The message was aimed at a dense ball of stars called M13, which is so far away that we will have to wait 50,000 years for a possible reply.
Some important facts
1) The very large array consists of 27 radio telescopes that can be moved to a distance of 36km apart on three railway tracks. This enables astronomers to have clearer view of space.
2) Project Argus, named after the Greek monster with 100 eyes, is an attempt to position 5,000 radio telescopes around the world to search for extraterrestrial signals. In fact, 5,000 telescopes are all that are needed to be able to see in every direction at once for a distance of several hundred light years.
3) As well as receiving signals from outer space, radio telescopes like the Arecibo telescope below can also broadcast signals to the entire galaxy and beyond, letting extrasolar civilisations know we are here!
Just as life started on our planet billions of years ago, it may well also have begun on an alien world. Evidence has already been found for extrasolar planets around the closest stars, and there are even suggestions of life on other worlds in the solar system itself. All these details have made scientists more and more optimistic that life exists somewhere else in space.
How likely is life?
The astronomer Frank Drake was one of the first to assess the probability of intelligent life elsewhere in the universe. He tried to estimate the number of civilisations in the galaxy with the means of communicating with us right now. He claimed that for intelligent life to arise on a planet, and to be able to communicate over long distances, conditions on the planet must be just right. His equation took into consideration a number of factors:
N=R*fp ne fl fi fc L
N= the number of civilisations with the ability to communicate over long distances.
R*= the rate of formation of suitable stars
fp= the fraction of those stars with the planets
ne= the number of Earth like worlds in a planetary system
fl= the fraction of Earth like worlds in which life develops
fi= the fraction of life forms that develops intelligence
fc= the fraction of intelligent life forms that develops electromagnetic communication technology
L= the lifetime of these communicating civilisations
Radio telescopes
The question "Is there anybody out there?" has been of great importance to humankind ever since we realised there were other suns in the sky, many with planets in orbit around them. But only within the last fifty years has technology advanced to the stage where we can begin to look for extrasolar life. Frank Drake realized that the most effective way to communicate with extrasolar civilisations was by using radio telescoped. These telescopes are positioned all over the world and can listen for any signals from space that may have been made by other life forms.
Arecibo
In 1974, a message was beamed into space from the Arecibo radio telescope in Puerto Rico. It was made up of 1,6799 pulses which, when arranged into a grid 23 columns wide and 73 rows tall, create an image. This image contains information about life on planet Earth. The message was aimed at a dense ball of stars called M13, which is so far away that we will have to wait 50,000 years for a possible reply.
Some important facts
1) The very large array consists of 27 radio telescopes that can be moved to a distance of 36km apart on three railway tracks. This enables astronomers to have clearer view of space.
2) Project Argus, named after the Greek monster with 100 eyes, is an attempt to position 5,000 radio telescopes around the world to search for extraterrestrial signals. In fact, 5,000 telescopes are all that are needed to be able to see in every direction at once for a distance of several hundred light years.
3) As well as receiving signals from outer space, radio telescopes like the Arecibo telescope below can also broadcast signals to the entire galaxy and beyond, letting extrasolar civilisations know we are here!
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