This image released by NASA shows an enhanced photo image of Mercury from its Messenger probe's 2008 flyby of the planet. (AP)WASHINGTON: For the first time, Earth has a regular orbiting eye-in-the-sky spying on the solar system's smallest and strangest planet, Mercury. NASA's spacecraft called Messenger successfully veered into a pinpoint orbit Thursday night after a 6 1/2-year trip and 4.9 billion miles (7.9 billion kilometers) and tricky maneuvering to fend off the gravitational pull of the sun. It is the fifth planet in our solar system that NASA has orbited, in addition to the Earth and the moon. Messenger is in orbit that brings it as close as 120 miles (193 kilometers) above the planet's surface. Mercury is not only difficult to get to, but it's has some of the most extremes in the solar system. Temperatures there swing wildly by 1,100 degrees. While it gets up to 800 degrees on the planet closest to the sun, it also is so cold and dark in some craters that the temperatures don't get above 300 degrees below zero. Radar even shows that there is likely frozen ice in those craters, something Messenger will try to confirm. In the 1970s, NASA sent a spacecraft, Mariner, whizzing by Mercury, but only got pictures of less than half of the tiny rock. Messenger, which cost NASA $446 million, was launched in 2004. Next month it should start transmitting pictures and investigate Mercury's mysterious magnetic field and unusual density.
