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News briefs: December 4
Posted: Wed, Dec 5, 2001, 7:56 AM ET (1256 GMT)
- An adaptive optics system at the European Southern Observatory is now capable of images as sharp as the Hubble Space Telescope, astronomers said Tuesday. The new NAOS-CONICA system at the Very Large Telescope is capable of producing images with resolutions of 0.04 to 0.07 arcseconds at infrared wavelengths. Such images are near the theoretical limits for telescopes the size of the VLT.
- Images from the Galileo spacecraft have provided new evidence of a subsurface ocean on Jupiter's moon Callisto, planetary scientists recently announced. Galileo images of the point on Callisto on the opposite side of the moon from the large impact crater Valhalla show no effect of that impact, unlike similar "antipodal" regions on rocky moons. Scientists believe that a subsurface ocean of liquid water cushioned the force of the impact and prevented shock waves from focusing at the antipodal region and creating hilly terrain.
- Mars may have once had proportionally more water than the Earth, scientists reported last week. In a paper published in the November 30 issue of the journal Science, scientists said that observations of the planet by the Far Ultraviolet Spectroscopic Explorer (FUSE) detected molecular hydrogen in the Martian atmosphere for the first time. Using this detection, a previous observation of deuterium in the atmosphere, and models, scientists concluded that Mars had up to 1.3 times more water per unit mass than the Earth when it was formed 4.5 billion years ago.
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