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Emily Lakdawalla • Aug 15, 2007

Uranus ring plane crossing tomorrow!

For the second time this year, Earth is crossing the ring plane of Uranus. I won't go in to much detail about this because I covered the Uranus ring plane crossings in detail in an April post. This crossing will take us back to the southern, sunlit side of the rings. I just exchanged emails with astronomer Imke de Pater, who is at the Keck observatory in Hawaii attempting to do observations through hurricanes (Flossie, which has just been downgraded to a tropical storm) and earthquakes (there was a magnitude 5.4 event 26 miles south of Hilo on Monday); I wish clear skies -- and no further earthquakes -- to all astronomers attempting to study this rare phenomenon!

Uranus Ring Plane Crossing

Mark Showalter and Mitch Gordon of the PDS Rings Node

Uranus Ring Plane Crossing
This graph shows how Earth's view of Uranus changes during the 2007-2008 ring plane crossing season. For decades, Earth's view has been of the southern hemisphere. But as Uranus approaches its equinox, Earth will briefly -- from May 2 to August 16 -- cross the ring plane to the shadowed side of the rings (gray part of the curve) and the northern hemisphere. Then Earth recrosses the ring plane on August 16. On December 7, Uranus reaches its equinox, and the Sun goes to the north side of the rings, leaving the southern side of the rings -- the side that Earth sees -- in shadow (again, gray part of the figure). Finally, on February 16, Earth recrosses to the north side of the ring plane, and the sunlit side of the rings, until the next equinox and ring plane crossing in 2049.

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