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The heavens are home to an alien world that shines a deep cobalt blue in a solar system far, far away from our own. Astronomers used the ageing Hubble space telescope to determine the true colour of the distant world, the first time such a feat has been achieved for a planet that circles a star other than the sun.
Unlike the pale blue dot that harbours all known life in the cosmos, the "deep blue dot" is an inhospitable gas giant that lies 63 light years from Earth. On HD189733b, as the planet is named, the temperature soars to 1,000C and glassy hail whips through the air on hypersonic winds.
Though the planet is hostile to life as we know it, the same technique could be used to spot potentially habitable worlds, through changes in cloud cover and other features.
Frederic Pont at Exeter University observed the planet before, during, and after it passed behind its star. When the planet was on either side, the telescope collected light from the star along with light reflected from the planet's surface. But as the planet moved behind the star, the light it reflected was blocked out.
Using an instrument onboard the telescope called an imaging spectrograph, Pont noticed that blue light dimmed sharply as the planet passed behind its star, but brightened again when it emerged on the other side. "As far as I am aware, nobody has had actual results on the colour of an exoplanet," Pont said. "Now we can say that this planet is blue."
The deep cobalt colouration is thought to come from a similar process to that which makes Earth look blue from space, namely the scattering of blue light in the atmosphere. On the planet Pont observed, the scattering is probably due to a fine mist of silicate particles that are blown around by 7,000kph winds.
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http://www.guardian.co.uk/science/2013/jul/11/alien-deep-blue-planet-astronomers
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Though only about dozen potentially habitable exoplanets have been detected so far, scientists say the universe should be teeming with alien worlds that could support life. The Milky Way alone may host 60 billion such planets around faint red dwarf stars, a new estimate suggests.
Based on data from NASA's planet-hunting Kepler spacecraft, scientists have predicted that there should be one Earth-size planet in the habitable zone of each red dwarf, the most common type of star. But a group of researchers has now doubled that estimate after considering how cloud cover might help an alien planet support life.
"Clouds cause warming, and they cause cooling on Earth," study researcher Dorian Abbot, an assistant professor in geophysical sciences at the University of Chicago, said in a statement. "They reflect sunlight to cool things off, and they absorb infrared radiation from the surface to make a greenhouse effect. That's part of what keeps the planet warm enough to sustain life."
The habitable zone is defined as the region where a planet has the right temperature to keep liquid water on its surface, thought to be a requirement for life as we know it. If a planet is too far from its star, its water freezes; too close, water vaporizes. Since red dwarfs are dimmer and cooler than our sun, their habitable zone is much cozier than our solar system's.
"If you're orbiting around a low-mass or dwarf star, you have to orbit about once a month, once every two months to receive the same amount of sunlight that we receive from the sun," explained another study author, Nicolas Cowan, a postdoctoral fellow at Northwestern University.
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http://www.space.com/21800-alien-planets-60-billion-habitable-exoplanets.html
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A team of astronomers has combined new observations of Gliese 667C with existing data from HARPS at ESO's 3.6-metre telescope in Chile, to reveal a system with at least six planets. A record-breaking three of these planets are super-Earths lying in the zone around the star where liquid water could exist, making them possible candidates for the presence of life. This is the first system found with a fully packed habitable zone.
Gliese 667C is a very well-studied star. Just over one third of the mass of the Sun, it is part of a triple star system known as Gliese 667 (also referred to as GJ 667), 22 light-years away in the constellation of Scorpius (The Scorpion). This is quite close to us -- within the Sun's neighbourhood -- and much closer than the star systems investigated using telescopes such as the planet-hunting Kepler space telescope.
Previous studies of Gliese 667C had found that the star hosts three planets with one of them in the habitable zone. Now, a team of astronomers led by Guillem Anglada-Escudé of the University of Göttingen, Germany and Mikko Tuomi of the University of Hertfordshire, UK, has reexamined the system. They have added new HARPS observations, along with data from ESO's Very Large Telescope, the W.M. Keck Observatory and the Magellan Telescopes, to the already existing picture [1]. The team has found evidence for up to seven planets around the star [2].
These planets orbit the third fainter star of a triple star system. Viewed from one of these newly found planets the two other suns would look like a pair of very bright stars visible in the daytime and at night they would provide as much illumination as the full Moon. The new planets completely fill up the habitable zone of Gliese 667C, as there are no more stable orbits in which a planet could exist at the right distance to it.
"We knew that the star had three planets from previous studies, so we wanted to see whether there were any more," says Tuomi. "By adding some new observations and revisiting existing data we were able to confirm these three and confidently reveal several more. Finding three low-mass planets in the star's habitable zone is very exciting!"
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http://www.sciencedaily.com/releases/2013/06/130625073544.htm
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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.
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http://www.telegraph.co.uk/science/space/9230801/Astronomers-find-new-planet-capable-of-supporting-life.html
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There should be billions of habitable, rocky planets around the faint red stars of our Milky Way galaxy, a new study suggests.
Though these alien planets are difficult to detect, and only a few have been discovered so far, they should be ubiquitous, scientists say. And some of them could be good candidates to host extraterrestrial life.
The findings are based on a survey of 102 stars in a class called red dwarfs, which are fainter, cooler, less massive and longer-lived than the sun, and are thought to make up about 80 percent of the stars in our galaxy.
Finding super-Earths
Using the HARPS spectrograph on the 3.6-metre telescope at the European Southern Observatory's La Silla Observatory in Chile, astronomers found nine planets slightly larger than Earth over a six-year period. These planets, called super-Earths, weigh between one and 10 times the mass of our own world, and two of the nine were discovered in the habitable zone of their parent star, where temperatures are right for liquid water to exist.
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http://www.space.com/15060-billions-habitable-alien-planets-red-dwarfs.html
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