The comet P/2013 P5 as seen by Hubble on September 10, 2013. P/2013 P5 is about 790 feet (240 m) in diameter. It has six comet-like tails of dust radiating from it like spokes on a wheel. From http://www.sci-news.com/space/science-p2013p5-hubble-asteroid-six-tails-01530.html.
At journal club today, we talked about two interesting papers.
The first, “The Extraordinary Multi-tailed Main-belt Comet P/2013 P5” by Jewitt and colleagues, discussed observations using the Hubble Space Telescope of a comet in the asteroid belt that displayed five cometary tails (see image at left). The tails are made of particles shed by the comet, and using the particle trajectories inferred from the tails, the authors were able to figure out when, over the last few months, the particles were launched from the comet.
The second article, “Evidence for high salinity of Early Cretaceous sea water from the Chesapeake Bay crater” by Sanford and colleagues, presented chemical analyses of water collected from under the Chesapeake Bay, in the large impact crater at the southern end of the bay. (The crater is underwater and buried by sediment, so you can’t see it even if you’re just standing on it.) The water contain subtle chemical signatures that indicate it was originally part of the Early Cretaceous North Atlantic Ocean, an extinct ocean from more than 100 million years ago. Chemical analyses of this buried water will tell scientists what the ancient ocean was like.
