Is There Extraterrestrial Life?
People have long speculated about intelligent life on other planets. Sometimes I wonder if there is any intelligent life here on Earth, but we will put that aside for now.
Scientists have been scanning the universe for signs of intelligent life. They have come up empty so far, but who knows? Perhaps someone has received the signal and is too cagey to just respond in kind.
The Search for Life
The nonprofit SETI Institute was founded in 1984 with a mission to “explore, understand and explain the origin, nature and prevalence of life in the universe.” SETI, of course, is an acronym for “search for extraterrestrial intelligence”.
People have searched for radio signals from space since a radio astronomer named Frank Drake aimed an antenna at a couple of Sun-like stars in 1960. The Soviet Union conducted a broad search in the 1960s. Activity grew in the United States after the National Aeronautics and Space Administration (NASA) analyzed the scientific and technological issues related to the search. NASA funded a High Resolution Microwave Survey Targeted Search in 1992. Said by Congress to be a waste of money, it was canceled in 1993. The SETI Institute took over the operation in 1994, renaming it the Phoenix Project and funding it with donations. The effort was suspended in April 2011 due to a shortage of funds. The Phoenix Project observed over 800 stars as far as 240 light years from Earth, finding no signs of life.
A light year is the distance that light travels in a year, and is a bit less than 6 trillion miles. Doing some quick math, 240 light years is around 1.4 quadrillion miles. It's sort of like the national debt, expressed in miles instead of dollars.
How Many Civilizations?
Led by astronomer Frank Drake (b. 1930), a team of scientists formulated the Drake equation in 1961 to estimate the number of detectable extraterrestrial civilizations in the Milky Way galaxy. The equation is complex and depends on a number of assumptions that can greatly affect the result. The answer ranges from less than a thousand to almost a billion. Drake suggested that the paucity of evidence of other civilizations might indicate that technological civilizations disappeared fairly rapidly. This, in turn, gave rise to speculation about the lifespan of civilization on Earth.
Astrobiologists assume the other lifeforms will be carbon-based, as we are, and will require water and a sun. Scientists have sent numerous probes to Mars, which is the closest place where life might exist. Dr. Seth Shostak, Senior Astronomer at the SETI Institute, suggests that life could exist on Saturn's moons, or in the upper atmosphere of Venus. These lifeforms would likely resemble bacteria.
The Search Goes On (And On, And On)
Scientists have not been passive in the search for life. The United States launched the Pioneer 10 and 11 spacecraft in 1973. These carried a plaque, designed by Drake and astronomer Carl Sagan (1934-1996), with information about humans, the Earth and the space missions. Pioneer 10 exited the solar system in 1983. According to Popular Science, it will be two million years before either craft encounters another star.
NASA also sent golden records with the Voyager probes. These explain how to play them, and they contain a map locating the Sun, along with videos, greetings in numerous languages and music from around the world. It will be tens of thousands of years before this information reaches its destination.
Meteorites bounce around the universe, and they sometimes carry bits of amino acids. About 20 different amino acids form the basis of life, and scientists have found eight of them on meteorites. They also study organisms on Earth called extremophiles. These creatures can survive, and possibly even thrive on extreme conditions such as near absolute zero temperatures and radioactive environments.
Astronomers had thought these types of lifeforms might live on Mars. The Telegraph reported in early February 2012 that after three years analyzing Martian soil collected during the 2008 NASA Phoenix mission, researchers stated that Mars has suffered a super-drought, perhaps for hundreds of millions of years, and that any life on the red planet would have to be deep underground.
Scientists discovered the first extrasolar planet orbiting a normal star in 1995. Called 51 Pegasi b, the planet is in the constellation Pegasus, about 50 light years from Earth. Its discovery confirmed ideas that our solar system might not be unique. By mid-2008, about 300 exoplanets had been found. NASA launched the Kepler space observatory in March 2009, and the spacecraft has already identified more than 60 planets and a few thousand planet candidates. In January 2012, the craft discovered 11 new planetary systems hosting at least 26 planets, according to Space.com. At that time, the Extrasolar Planets Encyclopaedia listed 729 exoplanets in 594 planetary systems and 88 multiple-planet systems. With the increasing number of planets being discovered, it's hard to believe that no other planet has intelligent life.
Aliens Among Us
Aliens have visited our planet many times in the movies, but scientists tend to believe it won't happen because of the energy required to travel through the vastness of space. Of course, they could discover a revolutionary energy source someday that could radically change that view.
Led by physicist Stephen Hawking, scientists are starting to acknowledge that alien life might well exist, according to big think. Conjuring up images from old Outer Limits TV shows, Hawking advised in a Discovery Channel documentary that we should avoid engaging aliens, which he called “nomads looking to conquer and colonize.”
Bulgarian scientist Lachezar Fiipov told the media, “Aliens are currently all around us, and are watching us all the time,” according to The Telegraph. The same publication reported the statement of Professor Chandra Wickramasinghe of Cardiff University that billions of years ago comets deposited microbes that multiplied and seeded to form human life. If that's true, then the aliens have already been here—and we are their descendants.
What's Your Opinion?
Will humans eventually encounter extraterrestrial intelligence?
New Candidate Planets Found
In February 2012, Scientific American reported the discovery of a planet named GJ 667Cc, which could support life. The planet is at least 4.5 times as massive as Earth. It orbits its parent star, 22 light years from Earth in the constellation Scorpius, in about 28 days. GJ 667Cc lies in the habitable zone of its host star, whose temperatures are appropriate for liquid water to exist on the planet's surface.
The planet is part of a star system whose makeup is quite different than ours, lacking particularly in metals, which are usually key in the formation of planets. Steven Vogt, an astronomer at the University of California, Santa Cruz, and one of the authors of the study announcing the planet's discovery, said, “Statistics tell us we shouldn't have found something this quickly this soon unless there's a lot of them out there. This tells us there must be an awful lot of these planets out there.”
The study was led by Guillem Anglada-Escudé and Paul Butler of the Carnegie Institution for Science. It will be published in the Astrophysical Journal Letters.
In April 2013, scientists announced the discovery by NASA's Kepler satellite of three new candidate planets. Rotating around the Kepler-62 star, two of the planets, Kepler-62e and Kepler-62f, lie in the habitable zone. A third planet, Kepler-69c, is somewhat less likely to accommodate life. The planets are about 1,200 light years from Earth. The Kepler-69 star is 2,700 light years away.
Billions of Habitable Planets May Exist in Our Galaxy
In late March of 2012, the Irish Independent reported on a study indicating that billions of habitable planets may exist in our galaxy, some within 30 light years of Earth.
A group of astronomers, led by Dr. Xavier Bonfils of Grenoble University in France, surveyed red dwarf stars and determined that about 40 percent had a rocky planet not much bigger than Earth orbiting the habitable zone where liquid water can exist, making life possible. There are about 160 billion such stars in the Milky Way, accounting for approximately 80 percent of all stars in the galaxy, leading to the astonishing conclusion that there are tens of billions of such planets just in our galaxy.
Scientists surveyed a specific group of 102 red dwarfs using a telescope at La Silla, Chile, and found nine super-Earths, planets with masses between one and 10 times that of Earth. From this, they estimated that there could be about 100 habitable-zone planets within 30 light years of Earth.