venerdì 5 febbraio 2010
Plutone come non l'abbiamo mai visto
Mistero Plutone. Di lui si sa poco o nulla, essendo il più lontano pianeta del sistema solare ed avendo un diametro di appena 2300 chilometri. Ma ora grazie al solito telescopio Hubble scopriamo alcuni dettagli in più del corpo celeste, in attesa delle immagini che ci invierà la sonda Horizons nel 2015, partita da Cape Canaveral nel 2006. Tratta, oggi, l'argomento il Telegraph… Pluto, now classed as a dwarf planet, is so small and so distant that its surface has been a mystery to astronomers. Nasa compared the challenge to trying to see the markings on a football 40 miles away. But the Hubble Telescope has been able to reveal a treacle-coloured, mottled world with a peculiar bright frosty spot. It also revealed seasonal changes just like on Earth. Pluto is less that 1,500 miles in diameter and lies at the edge of the solar system. It is so far from the sun that it takes 248 years to make one orbit. The new pictures are the best view we will have of Pluto until a space probe called New Horizons flies past it in 2015. The £400 million spacecraft - the fastest ever sent into the solar system - reached Jupiter just a year after launch. "The Hubble images will remain our sharpest view of Pluto until NASA's New Horizons probe is within six months of its Pluto flyby," a Nasa spokesman said. "The Hubble pictures are proving invaluable for picking out the planet's most interesting-looking hemisphere for the New Horizons spacecraft to swoop over when it flies by Pluto in 2015. "Though Pluto is arguably one of the public's favorite planetary objects, it is also the hardest of which to get a detailed portrait because the world is small and very far away." Principal investigator Marc Buie, of the Southwest Research Institute in Boulder, in Colorado, said the images allowed astronomers to better interpret more than three decades of Pluto observations from other telescopes. "The Hubble observations are the key to tying together these other diverse constraints on Pluto and showing how it all makes sense by providing a context based on weather and seasonal changes, which opens other new lines of investigation," he said.