Extraterrestrial life, sometimes colloquially referred to as alien life, is hypothetical life that may occur outside Earth and which did not originate on Earth. Such life might range from simple prokaryotes (or comparable life forms) to intelligent beings and even sapient beings, possibly bringing forth civilizations that might be far more advanced than humanity. The Drake equation speculates about the existence of sapient life elsewhere in the universe. The science of extraterrestrial life in all its forms is known as astrobiology, the multidisciplinary field that investigates the deterministic conditions and contingent events with which life arises, distributes, and evolves in the universe.Speculation about the possibility of inhabited "worlds" outside the planet Earth dates back to antiquity. Multiple early Christian writers discussed the idea of a "plurality of worlds" as proposed by earlier thinkers such as Democritus; Augustine references Epicurus's idea of innumerable worlds "throughout the boundless immensity of space" in The City of God. Pre-modern writers typically assumed that extraterrestrial "worlds" would be inhabited by living beings. William Vorilong, in the 15th century, acknowledged the possibility that Christ could have visited extraterrestrial worlds to redeem their inhabitants. Nicholas of Cusa wrote in 1440 that the Earth was "a brilliant star" like other celestial objects visible in space, which would appear similar to the Sun from an exterior perspective due to a layer of "fiery brightness" in the outer layer of the atmosphere. He theorized that all extraterrestrial bodies could be inhabited by men, plants, and animals, including the Sun. Descartes wrote that there was no means to prove that the stars were not inhabited by "intelligent creatures," but their existence was a matter of speculation. The writings of these thinkers show that interest in extraterrestrial life existed throughout history, but it is only recently that humans have had any means of investigating it.Since the mid-20th century, active research has taken place to look for signs of extraterrestrial life, encompassing searches for current and historic extraterrestrial life, and a narrower search for extraterrestrial intelligent life. Depending on the category of search, methods range from the analysis of telescope and specimen data to radios used to detect and send communication signals.The concept of extraterrestrial life, and particularly extraterrestrial intelligence, has had a major cultural impact, especially extraterrestrials in fiction. Over the years, science fiction has communicated scientific ideas, imagined a wide range of possibilities, and influenced public interest in and perspectives on extraterrestrial life. One shared space is the debate over the wisdom of attempting communication with extraterrestrial intelligence. Some encourage aggressive methods to try to contact intelligent extraterrestrial life. Others—citing the tendency of technologically advanced human societies to enslave or wipe out less advanced societies—argue that it may be dangerous to actively call attention to Earth.
Source: Extraterrestrial life (wikipedia.org)
Researchers believe there may be a planet that could sustain life, in the vicinity of a dying sun. If confirmed, this would be the first time that a potentially life-supporting planet has been found orbiting such a star, called a "white dwarf".
There's an air of relief in the science team running the American space agency's (Nasa) Perseverance rover on Mars. The researchers are sure now they've sent the robot to a location that provides the best possible opportunity to find signs of ancient life.
It's not possible for life to exist in the clouds of Venus. It's simply too dry, says an international research team led from Queen's University Belfast, UK.
The US government has said it has no explanation for dozens of unidentified flying objects seen by military pilots. It does not rule out the possibility that the objects are extra-terrestrial.
A highly anticipated US government report on UFOs (unidentified flying objects) has just been released. Here's what we know so far. The unclassified report was demanded by Congress after numerous reports from the US military of vehicles seen moving erratically in the sky.
image copyrightGetty ImagesA US government report on sightings of unidentified flying objects (UFOs) found no evidence of alien activity but does not rule it out, officials have told US media.The review of 120 incidents is expected to conclude that US technology was not involved in most cases.
It's an extraordinary possibility - the idea that living organisms are floating in the clouds of Planet Venus. But this is what astronomers are now considering after detecting a gas in the atmosphere they can't explain.
Trundling across the surface of Mars as you read this is a remarkable machine. Perseverance – the car-sized rover that safely touched down on the Martian surface on 18 February this year – might only have a top speed of less than 0.
Nasa's Perseverance rover, due to launch to Mars this summer, will search an ancient crater lake for signs of past life. But if biology ever emerged on the Red Planet, how will scientists recognise it? Here, deputy project scientist Ken Williford explains what they're looking for.
There's a new robot on the surface of Mars. The American space agency has successfully landed its Perseverance rover in a deep crater near the planet's equator called Jezero.
Nasa is sending a spacecraft to the icy world of Europa, which holds an ocean under its frozen outer shell. Scientists have long regarded the moon as one of the most promising targets in the search for life elsewhere in our Solar System.
Extraterrestrial life[n 1] is hypothetical life which may occur outside Earth and which did not originate on Earth.
Could "shadow life" be lurking in the deep ocean? Never mind Mars, alien life may be thriving right here on Earth, a major science conference has heard.
There is now even more evidence that life on Earth may have been seeded by material from asteroids or comets. Prior research has shown how amino acids - the building blocks of life - could form elsewhere in the cosmos.
US scientists have found further evidence that huge seas existed long ago on Mars. The 2,000 km-wide, 8km-deep Hellas basin is a giant impact crater - the largest such structure on Mars.
For decades, scientists have been sending robotic probes deep into the Solar System, revealing a diverse and dynamic array of worlds orbiting the Sun. Unmanned spacecraft have transformed understanding of our cosmic neighbourhood. But this avalanche of data has also thrown up many new questions.
It may not rank as the most compelling reason to curb greenhouse gases, but reducing our emissions might just save humanity from a pre-emptive alien attack, scientists claim.
Not many scientists are prepared to take tales of alien abduction seriously, but John Mack, a Harvard professor who was killed in a road accident in north London last year, did. Ten years on from a row which nearly lost him his job, hundreds of people who claim they were abducted still revere him.
The next generation of telescopes could reveal the presence of oceans on planets outside our Solar System. Detecting water on Earth-like planets offers the tantalising prospect they could sustain life.
Seti, the Search for Extraterrestrial Intelligence, has until now sought radio signals from worlds like Earth. But Seti astronomer Seth Shostak argues that the time between aliens developing radio technology and artificial intelligence (AI) would be short.
While searching deep space for extra-terrestrial signals, scientists at the Arecibo Observatory in Puerto Rico have stumbled across signals broadcast from Earth nearly half a century ago. Radio astronomer Dr.
The hunt for other intelligent civilisations has a new technique in its arsenal, but its first use has turned up no signs of alien broadcasts. Australian astronomers used "very long baseline interferometry" to examine Gliese 581, a star known to host planets in its "habitable zone".
The US government has formally denied that it has any knowledge of contact with extraterrestrial life. The announcement came as a response to submissions to the We The People website, which promises to address any petition that gains 5,000 signatories.
The powerful vision of the Hubble Telescope - which turns 20 this week - has expanded our cosmic horizons and brought into sharper focus a new set of mysteries about the universe that is our home. To those whose science is gleaned from the media, astronomy may seem to be on a roll. And it is.
US defence officials have announced the launch of a task force to investigate reports of unidentified flying objects in restricted airspace. The group will assess objects of interest and "mitigate any associated threats", the Pentagon said on Tuesday.
The US Department of Defense has released three declassified videos of "unexplained aerial phenomena". The Pentagon said it wanted to "clear up any misconceptions by the public on whether or not the footage that has been circulating was real".
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