March 12, 2013 2:09 pm
High in orbit above the Earth, the Solar Dynamics Observatory watches the Sun year-round, providing stunning stellar views that go unbroken except during a few special times each year. Because the SDO stays relatively fixed over one part of the planet in a geosynchronous orbit, the satellite goes through two annual “eclipse seasons.” For a few weeks twice each year, part of SDO’s view each day will be blocked by the Earth. And, three times a year, the Moon will get in the way.
Though a bit of a pain for the scientists trying to study the Sun, these orbital quirks provide some beautiful unintended consequences: gorgeous photos of an eclipse from space. Yesterday, NASA released photos and video of that day’s double whammy, a single day that saw both a terrestrial and lunar eclipse.
One beautiful feature to notice is the apparent fuzziness of the Earthly eclipse. According to NASA, this is because of Earth’s atmosphere. The Moon, for the same reason, appears as a sharp disk.
When Earth blocks the sun, the boundaries of Earth’s shadow appear fuzzy, since SDO can see some light from the sun coming through Earth’s atmosphere. The line of Earth appears almost straight, since Earth — from SDO’s point of view — is so large compared to the sun.
The eclipse caused by the moon looks far different. Since the moon has no atmosphere, its curved shape can be seen clearly, and the line of its shadow is crisp and clean.
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