(1) I have nothing against scientific surveys scanning the heavens for signs of extraterrestrial intelligence.

(2) Meteorites, on the other hand, are extraterrestrial material that have made it to Earth's surface and can weigh many tons.

(3) As only Earth meets this requirement, there is no extraterrestrial life in the solar system.

(4) The period of these signals was so precise that they were initially thought to be signs of extraterrestrial intelligence.

(5) Not far from the site of delivery of Earth's first extraterrestrial calling card was a pretty little dell.

(6) The researchers still didn't detect extraterrestrial microorganisms on Earth.

(7) One additional data point about how frequently life occurs in the universe is not going to settle any debates about extraterrestrial intelligence.

(8) It appears increasingly likely that there are extraterrestrial environments that could support Earth organisms.

(9) Meanwhile, belief in extraterrestrial intelligences continues to grow with an almost religious fervour.

(10) A former teacher founded the cult in 1969 and claimed to have shielded earth from extraterrestrial invasion on numerous occasions.

(11) Scientists are of two minds regarding the existence of extraterrestrial intelligence.

(12) It is possible that the increase of stardust in the Solar System will influence the amount of extraterrestrial material that rains down to Earth.

(13) I suggest that green fireballs may be extraterrestrial probes entering our atmosphere.

(14) Obviously if UFOs are as rampant as people claim, SETI would be overloaded with messages of extraterrestrial intelligence.

(15) No other robotic spacecraft has ever collected extraterrestrial material and returned it to Earth.

(16) Richard and Scott both believed there was extraterrestrial life beyond Earth.

(17) Other sources of high iridium concentrations are extraterrestrial objects, such as meteorites or comets.

(18) But, Sagan was also known for his optimistic search for extraterrestrial intelligence.

(19) Organic molecules, such as amino acids, organic acids, and sugars have been observed in material from extraterrestrial sources in the solar system.

(20) Despite the likelihood that humans are alone in the universe, the search for extraterrestrial intelligence will continue, said famed scientist Jill Tarter.