But in the early universe, as Loeb speculates in a paper published in Astrobiology late last year, everything would have been a habitable zone. 10 to 20 million years after the Big Bang, the universe was still bathed in that warm gas we saw in the CMB, but it had cooled down to a temperature that would keep water liquid no matter where it was relative to its star. The ambient temperature of the universe would provide enough heat to turn an ice giant like Neptune into a water giant. That’s why Loeb has dubbed this era the “habitable epoch.”
It would have been a weird time for life to evolve, though. Many of the building blocks of life on Earth, like carbon and metals, exist only because of the massive stellar explosions called supernovas which signal the deaths of stars. In a universe where so few stars had been born, even fewer would have died. This was a period when solid matter was an anomaly, before most of the elements on the periodic table existed.
Stars would have been few and far between. “Life might have been more isolated than it is today,” Loeb said. “Now we are members of a galaxy, with tens of billions of stars not far away.” Still, Loeb said, the rare stars and planets would form hotter, more energetic regions in the sea of warm gas. There would be energy to kick-start life forms and liquid water would slosh across the surface of planets with atmosphere. Also, the relative isolation of these worlds would have protected them from threats like cosmic radiation and asteroid bombardment—two dangers that have nearly extinguished life on Earth more than once.
Would this life have been intelligent? “No,” Loeb said. “I’m talking about very simple organisms like algae.” Because the universe was changing so quickly, species would only have about a million years to evolve on a planet before the warm gas clouds around it cooled enough to change the environment radically. Still, a million years is enough time for a single-celled creature to evolve. And another simple species, more adapted to the colder world, could evolve to take its place. But could a humanlike civilization arise in one of those evolutionary windows? The odds are slim—consider that it took roughly 65 million years for the small, fluffy mammals of the Tertiary period to evolve into modern humans.
A Newly Confirmed Planet in the Habitable Zone and 42 Long-Period Planet Candidates Identified Using the Kepler Data
Just thought I would say, having nothing else to say this evening, that my real world name is in this list.
A rocky exoplanet the size of Earth has been unveiled in the closest star system to the Sun, the Alpha Centauri triple system, just 4.3 light years away. The planet, found by the HARPS instrument at the European Southern Observatory, is too close to its star for life but the discovery – hailed as the greatest since the first exoplanets were discovered 20 years ago – tantalisingly hints at the possibility of a planet existing in the habitable zone.
Astronomers have discovered their “holy grail” - a planet capable of supporting life outside our solar system.
The planet lies in what they describe as a ‘habitable zone’, neither too near its sun to dry out or too far away which freezes it.
And the discovery could help answer the question of whether we are alone in the universe, which has been plagued astronomers and alien fanatics for years.
Scientists found the planet, Gliese 667Cc, orbiting around a red dwarf star, 22 light years away from the earth.
Red dwarf stars are the most common stars in the neighbourhood of the sun, usually hosting planets called gas giants, which are not composed of rock matter.
Re-analysing data from the European Southern Observatory, the astronomers found Gliese 667Cc is a solid planet with roughly four and a half times the mass of Earth.
The University Göttingen and University of California scientists have calculated the planet recieves ten per cent less light from its red dwarf star than the Earth gets from the Sun.
As the light is in the infrared area, the planet still receives nearly the same amount of energy as the Earth, meaning water could be liquid and surface temperatures could be similar to ours.
Astronomers are hailing the plant as the ‘Holy Grail’ of discoveries, as 20 years ago scientists were still arguing about the existence of planets beyond our solar system.
Since the discovery of the first extrasolar planet in 1995, astronomers have confirmed the existence of more than 760 planets beyond the solar system, with only four believed to be in a habitable zone.
One of the most successful tools of planet hunters is the High Accuracy Radial Planetary Searcher (HARPS) telescope, which measures the radial velocity of a star.
Scientists using this telescope analyse the small wobbles in a stars motion caused by the gravitational response of a planet, determining the position and size of a planet indirectly.
Currently, they can detect planets which are 3-5 times the mass of the Earth but, in the future, they could detect planets which are smaller than twice the mass of Earth.
Steven Vogt, an astronomer from the University of California, said: “It´s the Holy Grail of exo-planet research to find a planet orbiting around a star at the right distance so it´s not too close where it would lose all its water and not too far where it would freeze.
“It´s right there in the habitable zone - there´s no question or discussion about it. It is not on the edge. It is right in there.”
Guillem Anglada-Escudé, of University Göttingen, Germany, said: “With the advent of new generation of instruments, researchers will be able to survey many dwarf stars for similar planets and eventually look for spectroscopic signatures of life in one of these worlds.”
Astronomers have detected a rocky “super-Earth” planet orbiting a nearby star in a region where life could possibly exist, a finding that led one of the team from UC Santa Cruz to predict there must be billions more of them in the Milky Way.
The new-found planet is a big one, at least four and a half times as massive as Earth. It is 22 light-years from Earth,orbits its star every 28 days, and lies in the star’s “habitable zone,” where temperatures are just right - neither too hot nor too cold - for liquid water to support life on its surface.
Carnegie Institution for Science - An artist’s conception of the alien planet GJ 667Cc, which is located in the habitable zone of its parent star.
The Allen Telescope Array (ATA) is once again searching planetary systems for signals that would be evidence of extraterrestrial intelligence. Among its first targets are some of the exoplanet candidates recently discovered by NASA’s Kepler space telescope.
“This is a superb opportunity for SETI observations,” said Jill Tarter, the Director of the Center for SETI Research at the SETI Institute.
“For the first time, we can point our telescopes at stars, and know that those stars actually host planetary systems - including at least one that begins to approximate an Earth analog in the habitable zone around its host star. That’s the type of world that might be home to a civilization capable of building radio transmitters.”
The ATA had been placed in hibernation mode last April as the result of the withdrawal of the SETI Institute’s former partner, U.C. Berkeley, due to budgetary shortfalls. Berkeley was the operator of the Hat Creek Observatory in northern California where the ATA is located. With new funding recently acquired for observatory operations, the ATA can resume SETI observations where it left off: examining the thousands of new candidate planets found by Kepler.
Summary: Astronomers are re-thinking the requirements that need to be met for an exoplanet to be considered ‘habitable.’ A new simulation of the Gliese 581 system is helping astrobiologists refine their search for Earth-like worlds in the Universe. Gleise 581 recently made news because a planet could be orbiting within the system’s habitable zone.