Related topics: nasa

Ceres: The tiny world where volcanoes erupt ice

Ahuna Mons is a volcano that rises 13,000 feet high and spreads 11 miles wide at its base. This would be impressive for a volcano on Earth. But Ahuna Mons stands on Ceres, a dwarf planet less than 600 miles wide that orbits ...

Ceres' bright spots seen in striking new detail

The brightest spots on the dwarf planet Ceres gleam with mystery in new views delivered by NASA's Dawn spacecraft. These closest-yet views of Occator crater, with a resolution of 450 feet (140 meters) per pixel, give scientists ...

Closer view of Ceres shows multiple white spots

NASA's Dawn spacecraft has acquired its latest and closest-yet snapshot of the mysterious dwarf planet world Ceres. These latest images, taken on Feb. 4, from a distance of about 90,000 miles (145,000 km) clearly show craters ...

Does Asteroid Vesta have a moon?

(PhysOrg.com) -- NASA's Dawn spacecraft is closing in on Vesta, and from now until the ion-powered spacecraft goes into orbit in mid-July, every picture of the giant asteroid will be the best one ever taken. What will researchers ...

Dawn maps Ceres craters where ice can accumulate

Scientists with NASA's Dawn mission have identified permanently shadowed regions on the dwarf planet Ceres. Most of these areas likely have been cold enough to trap water ice for a billion years, suggesting that ice deposits ...

Astronomers discover unexpected changes of bright spots on Ceres

Ceres is the largest body in the asteroid belt between Mars and Jupiter and the only such object classed as a dwarf planet. NASA's Dawn spacecraft has been in orbit around Ceres for more than a year and has mapped its surface ...

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Dawn

Dawn is the time that marks the beginning of the twilight before sunrise. It is recognized by the presence of weak sunlight, while the sun itself is still below the horizon. Dawn should not be confused with sunrise, which is the moment when the leading edge of the sun itself appears above the horizon.

The duration of the twilight period between dawn and sunrise varies greatly depending on the observer's latitude, from a few minutes in equatorial regions to many hours in polar regions. Dawn may easily be determined by observing a thread. When the color of a thread can be determined, changing from black to the thread's distinctive color, the 'crack of dawn' has occurred. This same measure of ambient light can be used to determine, conversely, the instant of dusk.

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