A few days ago—Sunday at 20:44 UTC (4:44 p.m. EDT), to be exact—was the moment of the autumnal equinox. There are a number of ways to explain this, though the definition is that it’s the moment the center of the Sun’s disk has a declination of zero degrees when it’s...
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Comet Lovejoy, Earth's Horizon (NASA, International Space Station, 12/22/11)
On July 19, NASA's Cassini spacecraft captured a rare image of Saturn's rings and our planet Earth and its moon.