GlobalWatch

Is nearly opaque Ceres the new water planet?8226; For years astronomers have tried to look closely at Ceres, the largest asteroid in the as...

Is nearly opaque Ceres the new water planet?
8226; For years astronomers have tried to look closely at Ceres, the largest asteroid in the asteroid belt, a nearly opaque target so featureless that scientists could not even be sure of its shape. But with the help of the Hubble Space Telescope, a team of researchers obtained enough images in enough detail to determine that Ceres is quite likely a 8216;8216;mini-planet8217;8217; with enough gravity to make it almost spherical, and suggesting that, like Earth, it may have different layers, including a mantle composed mostly of water ice.

The research was reported last week in Nature. Using Hubble8217;s Advanced Camera for Surveys, the team tracked Ceres through its full nine-hour rotation, and with 700 pixels in each image were able to follow a 8216;8216;bright spot8217;8217; as it moved around the asteroid, enabling them to determine its polar and equatorial axes. Team member Lucy McFadden of the University of Maryland said scientists had thought that Ceres was homogeneous in composition because of its smooth surface and its low-density surface crust.

8216;8216;But it was too round,8217;8217; McFadden said in a telephone interview. If it had been homogeneous, she said, centrifugal forces would have collapsed the light-density material into a more 8216;8216;oblate8217;8217; shape8212;flatter on top, swollen in the middle.

8216;8216;There8217;s something that8217;s keeping it from collapsing on itself,8217;8217; McFadden said, and the likeliest suspect is water ice, which expands when it freezes. If that is so, Ceres8212;only 580 miles in diameter8212;may have more fresh water on it than Earth.

New digital mammogram detects cancer in more cases
8226; A new computerized version of mammography is significantly better than the standard test at catching breast cancer in many women, according to a major government study. The study of nearly 50,000 US women found so-called digital mammography picked up somewhere between 15 per cent and 28 per cent more cancers in women younger than 50, those who had not yet gone through menopause, and those with dense breasts.

Although the test offers no advantage for other women, more than half of those getting mammograms fall into the categories that do benefit, experts said.

8220;It8217;s not a magic bullet, but this does find more of the cancers that kill women in these groups,8221; said Etta Pisano, of the University of North Carolina, Chapel Hill, who led the study. 8212; Agencies