by Astrobiology Magazine staffwriter
Three Tough Questions
Q: Approximately how many stars are there in the universe?
A: The number of stars in the visible universe is estimated to be 70 sextillion, or 70,000,000,000,000,000,000,000 [seven followed by twenty-two zeros].
and some Info to this
ten times more than the number of grains of sand on Earth
eleven times the number of cups of water in all the Earth’s oceans
ten thousand times the number of wheat kernels that have ever been produced on Earth
one hundred million times more than the number of ants in all the world
one hundred million times the dollar value of all the market-priced assets in the world
ten billion times the number of cells in a human being
one hundred billion times the number of letters in the 14 million books in the Library of Congress
…
Q: How many stars have scientists examined so far?
A: In any great detail, perhaps about 10,000 stars. It depends on if the question refers to whether stars are looked at in visual light or as radio sources. It also is not so much the stars themselves, but the number of habitable planets that is important.
…
Q: In doing a radio search, what kinds of signals are looked for?
A: SETI radio search involves a frequency that is relatively quiet, between 1000 and 10,000 MHz–just above the frequencies used by electronic pagers and some wireless cell phones at 900 MHz. The most abundant molecules are hydrogen, either neutral gas at 1420 MHz or combined with oxygen at 1640 MHz. In the spectrum of background that rains on our planet from interstellar space, this quiet region is called the 'water-hole ', because water molecules (necessary for life as we know it terrestrially), has this vibration.
Modern SETI efforts began with a paper writt. They published in the science press in 1959. By Giuseppe Cocconi and Philip Morrison suggested that the microwave frequencies between 1000 and 10,000 megahertz would be best suited for interstellar communications.
Full Story at Astrobiology Magazine
Very Interesting…
Sir Ulli
