“It lies in the [life-supporting] habitable zone, and it could have an ocean at its surface,” Michel Mayor said during the European Week of Astronomy and Space Science conference.
First discovered in 2007, Gliese 581d was originally calculated to be too far away from its host star—and therefore too cold—to support an ocean.
But Mayor and colleagues now show that the extrasolar planet, or exoplanet, orbits its host in 66.8 days, putting it just inside the cool star’s habitable zone.
At the same time, Mayor and colleagues announced that they have spotted a fourth planet orbiting in the Gliese 581 star system—and it’s the lightest exoplanet found so far.
The planet, dubbed Gliese 581e, is only about twice the mass of Earth and is the closest planet to the star, completing its orbit in about 3.15 days.
Science behind discovering planets
There are an estimated 10 billion planetary systems in our galaxy alone, yet to-date, only a few hundred have been discovered. Exoplanets are very difficult to detect because they don’t emit any light of their own and are completely obscured by their extremely bright parent stars. Normal telescope observation techniques cannot be used. Instead of trying to image/detect exoplanets directly we look for the physical effects they have on their parent star such as shifts in position or changes in brightness.
The SuperWASP(Wide Area Search for Planets) technique involves two sets of cameras to watch for events known as transits, where a planet passes directly in front of a star and blocks out some of the star’s light. From the Earth the star temporarily appears a little fainter. The SuperWASP cameras work as robots, surveying a large area of the sky at once. Each night astronomers receive data from millions of stars. They can then check for transits and hence planets. The transit technique also allows scientists to deduce the size and mass of each planet.
India on Friday became the fourth nation to have its flag flying on the Moon’s surface when Chandrayaan-1’s Moon Impact Probe device, – which has the Indian Tricolour painted on it – touched down. The 35-kilo payload crash-landed on the lunar surface at around 2030 hrs IST. The MIP has started sending its first signals to the satellite.
It also contains equipment which will help scientists design a lunar lander or rover for the upcoming Chandrayaan-2 mission.
There’s a lot tucked away inside the MIP. There’s a device to constantly check it’s height as it falls, another to check what the air on the moon is made of and even a video camera to photograph the moon from close range. Those photographs will help ISRO decide where to land India’s first moon rover, a few years from now. The MIP also has the Indian flag painted on its sides a Sanskrit shloka as well.
These two are close up pictures of the moon’s surface taken by Moon Impact Probe (MIP) on November 14, 2008 as it approached it after separating from Chandrayaan-1 spacecraft. Please note that these pictures are reproduced as received.
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Artist’s concept of the star Fomalhaut and the Jupiter-type planet that the Hubble Space Telescope observed. A ring of debris appears to surround Fomalhaut as well. The planet, called Fomalhaut b, orbits the 200-million-year-old star every 872 years. Credit: ESA, NASA, and L. Calcada (ESO for STScI)
Estimated to be no more than three times Jupiter’s mass, the planet, called Fomalhaut b, orbits the bright southern star Fomalhaut, located 25 light-years away in the constellation Piscis Australis, or the “Southern Fish.”
This visible-light image from the Hubble shows the newly discovered planet, Fomalhaut b, orbiting its parent star.
The planet is brighter than expected for an object of three Jupiter masses. One possibility is that it has a Saturn-like ring of ice and dust reflecting starlight. The ring might eventually coalesce to form moons. The ring’s estimated size is comparable to the region around Jupiter and its four largest orbiting satellites.
Future observations will attempt to see the planet in infrared light and will look for evidence of water vapor clouds in the atmosphere. This would yield clues to the evolution of a comparatively newborn 100-million-year-old planet. Astrometric measurements of the planet’s orbit will provide enough precision to yield an accurate mass.
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