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SYFY WIRE Bad Astronomy

Sic Transit, Glorious

By Phil Plait
BadAstronomyHero

This is what I've been waiting for: the stunning video views of NASA's Solar Dynamics Observatory of the Venus transit. Sit down, set this video to high-def, tune out everything else for 3 minutes 7 seconds, and soak in the clockwork glory of our solar system.


OK, you can breathe now. NASA has provided high-resolution versions for download, too.

SDO orbits the Earth about 40,000 kilometers (24,000 miles) above the surface of the Earth, with a nearly-continuous view of the Sun -- so it had the best seat in the Universe for the transit. One of its most important tasks is to observe the Sun in ultraviolet, where our star's magnetic activity is most obvious. The views in the video show the Sun different parts of the ultraviolet spectrum, colored to make them easier to see: magenta is at 1700 Angstroms (a unit of length astronomers like; 100 million Angstroms would comfortably fit across your fingernail), red is 304 Angstroms, and gold is 171 Angstroms. The orange segment is from the light we can see, about 3000 - 7000 Angstroms.

The Sun's ethereal outer atmosphere, its corona, glows at at 171 and 304 Angstroms. In visible light the transit lasted about 7 hours, but in the UV it took longer since the silhouette of Venus can be seen against the softly luminous corona.

SDO was commanded to take images faster than usual, to provide as much coverage of the transit as possible, so the passage of the planet across the Sun is smooth and -- I know, but it fits -- other-worldly.

And I can't help but think about a sad milestone today: one of America's -- one of the world's -- greatest writers, Ray Bradbury, has died. Among his many works was "The Long Rain", a short story which took place on Venus. It had a huge impact on me when I first read it as a kid, and it still makes me think about human nature, space exploration, and what happens when we mix the two.

Bradbury was more than a writer, he was a poet, and his works inspired generations of people to look beyond the borders of our world while still considering our humanity. We all must go someday, and for him to do so on the eve of the last transit of Venus to be seen for over a century is, somehow, fitting.

Ray Bradbury knew that no matter where we are, whether we are looking down into the water of another world, or looking up into the skies, what we are always seeing is a reflection of ourselves.

Sic transit gloria mundi.

Credit: NASA/SDO


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