The greatest hunt in human history is taking place, the hunt for exoplanets—worlds beyond our solar system.
The alien planets hang like rare jewels in space, although they may not be too rare for astronomers seem to be finding new ones almost every week.
The greatest prize though is finding planets that fall within the so-called "Goldilocks" range: planets that are not too hot, not too cold, and just right to support life. At least life as we know it.
While nearly 900 exoplanets have been discovered and charted around a myriad of star systems, some pretty exotic, only a relative handful are believed to possess an environment able to support life. Rarer still are those planets in our galaxy that are near the size and mass of Earth, have abundant water, and temperatures in the zone that makes life highly likely. When a planet like that is found fairly close to Earth astronomers throw a party.
Recently, astronomers, astrophysicists and exobiologists have had plenty of cause to celebrate. Two Earth-like planets have been found near us (near, that is, on a galactic scale), and theoretically humans may one day set foot on them.
The promise of Tau Ceti
The star system of Tau Ceti is a mere 12 light years from Earth, on a galactic scale it's in our neighborhood. According to the science website Gizmodo.com, the star can be seen with the naked eye and at least five planets are orbiting it.
Astronomer James Jenkins of Universidad de Chile told Gizmodo, "Planetary systems found around nearby stars close to our Sun indicate that these systems are common in our Milky Way galaxy."
What that means is habitable planets are most likely in abundance throughout the galaxy and uncounted billions must orbit stars throughout the universe. Many could sustain life—some exotic, others similar to life on Earth. There may even be star systems with several planets that have life orbiting the same star. The more likely life is near ubiquitous, the more likely some of it will be intelligent.
Not too many decades ago, many astronomers wondered if our solar system was unique, or rare. Now the view of astronomers and cosmologists has shifted dramatically. Some believe that virtually every star has planets, or in the case of red giants, once did.
A scientist that holds this view is one of the authors of the current study, UC Santa Cruz professor of astronomy and astrophysicist Steve Vogt. He told Gizmodo that, "…this discovery is in keeping with our emerging view that virtually every star has planets, and that the galaxy must have many such potentially habitable Earth-sized planets."
The study is published in the peer-reviewed journal Astronomy & Astrophysics.
Although the distance to Tau Ceti may seem insurmountable (the star is some 70.5 trillion miles distant) technology on the horizon may get explorers there. A nuclear-powered, self-contained space vessel traveling at half light speed could make the trip in about a quarter of a century.
Besides the quest for life, potential space colonies around other stars are also being considered. Naturally, that's a longer term view as until and unless something like a Star Trek warp drive is achieved travel between even nearby stars could take a lifetime or longer.
Another 'super-Earth' discovered
Almost overlapping the discover of the Tau Ceti planetary system,
An international team of astronomers headed by Mikko Tuomi, discovered a new planet orbiting the dwarf star designated as HD 40307 located in the Southern Hemisphere constellation called Pictor.
The new planet, that has an Earth-like signature, is labeled as HD40307g and a member of a six planet system. At 42 light year's it's farther than the Tau Ceti system, but still relatively close.
Discussing the new planet, Mikko Tuomi told SpaceDaily: "We pioneered new data analysis techniques including the use of the wavelength as a filter to reduce the influence of activity on the signal from this star. This significantly increased our sensitivity and enabled us to reveal three new super-Earth planets around the star known as HD 40307, making it into a six-planet system." [Study available here.]
Special mention has been made of the previous archived work from the European Southern Observatory. The team made their discovery after a thorough reanalysis of the data.
Meanwhile, a new report from a research team of geologists and astronomers at Ohio State University is finding evidence that as the search for life on exoplanets expands there may be planetary systems more habitable than ours.
Scientists once believed we were alone in the universe, now it's beginning to appear as if we're in the middle of a population boom.