GSFC: Swift Spies a Comet Slowdown

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GSFC: Swift Spies a Comet Slowdown

Post by bystander » Fri Jan 12, 2018 8:00 pm

Swift Mission Spies a Comet Slowdown
NASA | GSFC | Neil Gehrels Swift Observatory | 2018 Jan 10
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Observations by NASA's Swift spacecraft, now renamed the Neil Gehrels Swift Observatory after the mission’s late principal investigator, have captured an unprecedented change in the rotation of a comet. Images taken in May 2017 reveal that comet 41P/Tuttle-Giacobini-Kresák — 41P for short — was spinning three times slower than it was in March, when it was observed by the Discovery Channel Telescope at Lowell Observatory in Arizona.

The abrupt slowdown is the most dramatic change in a comet's rotation ever seen. ...

Ground-based observations established the comet's initial rotational period at about 20 hours in early March 2017 and detected its slowdown later the same month. The comet passed 13.2 million miles (21.2 million km) from Earth on April 1, and eight days later made its closest approach to the Sun. Swift's UVOT imaged the comet from May 7 to 9, revealing light variations associated with material recently ejected into the coma. These slow changes indicated 41P's rotation period had more than doubled, to between 46 and 60 hours. ...

A rapid decrease in the rotation rate of comet 41P/Tuttle–Giacobini–Kresák - Dennis Bodewits et al
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