Monday, August 3, 2009

SATURN

The moon is also one of the brightest objects in our solar system because the ice covering its surface reflects almost 100 percent of the sunlight that strikes it. One of Saturn’s 53 moons (so far identified) Enceladus reflects so much of the sun’s energy that its surface temperature is about -201° C (-330° F).

Of the one million galaxies that make up Galaxy Zoo's image bank, the team found only 250 Green Peas. "No one person could have done this on their own," Cardamone said. "Even if we had managed to look through 10,000 of these images, we would have only come across a few Green Peas and wouldn't have recognized them as a unique class of galaxies."

The model reveals that Enceladus initially had a frozen shell composed of a mixture of ammonia and water ice surrounding a rocky core. Over time, as Enceladus interacted with other moons, a small amount of heat was generated above the silicate core which made the ice shell separate into chemically distinct layers. An ammonia-enriched liquid layer formed on top of the core while a thin layer of pure water ice formed above that. The work will be published in the August issue of the planetary science journal, Icarus.

Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro

Forgetting to sow the seeds

To arrive at a solution, astronomers needed to probe the behemoth in still finer detail. To do this Keiichi Ohnaka from the Max Planck Institute for Radio Astronomy in Bonn, Germany, and his colleagues used interferometry. With the AMBER instrument on ESO’s Very Large Telescope Interferometer, which combines the light from three 1.8-metre Auxiliary Telescopes of the VLT, the astronomers obtained observations as sharp as those of a giant,

The AMBER observations revealed that the gas in Betelgeuse's atmosphere is moving vigorously up and down, and that these bubbles are as large as the supergiant star itself. Their unrivalled observations have led the astronomers to propose that these large-scale gas motions roiling under Betelgeuse’s red surface are behind the ejection of the massive plume into space.

virtual 48-metre telescope.

Although capable of affecting sunlight after five days, the growing aerosols would not yet be large enough to collect water droplets. The full impact on clouds only becomes evident two or three days later. It takes the form of a loss of low-altitude clouds, because of the earlier loss of small aerosols that would normally have grown into "cloud condensation nuclei" capable of seeding the clouds. "Then it's like noticing bare patches in a field, where a farmer forgot to sow the seeds," Svensmark explains. "Three independent sets of satellite observations all tell a similar story of clouds disappearing, about a week after the minimum of cosmic rays."

With such superb resolution, the astronomers were able to detect indirectly details four times finer still than the amazing NACO images had already allowed (in other words, the size of a marble on the ISS, as seen from the ground).

Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro


Am vazut multe ceasuri superbe pe www.topceas.ro