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Comets, exoplanets and undiscovered worlds

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“Why study comets? One reason is that in the public’s eye, they’re very spectacular, and a really bright one comes on average every ten years,” said Dr. Michael F. A’Hearn from the University of Maryland at College Park’s Department of Astronomy. “Scientifically we study them because they provide explanations for how we got here. Comets give us clues as to how life may have started on the planet earth.”

Dr. A’Hearn was the featured speaker for the Friends of the David M. Brown Arlington Planetarium’s March weekend, themed Exoplanets. The weekend started on Friday March 21st with the debut of the full-dome show, Undiscovered Worlds. Dr. A’Hearn’s lecture titled “Why Comets?” took place on March 22nd, and the weekend concluded on Sunday March 23rd with a second showing of Undiscovered Worlds followed by a showing of the popular children’s program, the Magic Treehouse.

Comets are cold on the inside and thus the chemistry is preserved. This preservation has allowed us to find some interesting things such as amino acids, water, carbon dioxide and polymers,” Dr. A’Hearn said continuing to discuss the valuable information that comets hold.

“This is a typical comet,” Dr. A’Hearn said describing the anatomy of comets to the audience. “There is a nucleus which we almost never observe from earth. 50% of the nucleus is empty space. There isn’t much gravity, but there is also not much force, so the little gravity that there is sufficient to hold it together.” He continued, “If you were to put a comet right here on earth, the tail would extend all of the way to the moon.”

Dr. A’Hearn went on to describe other aspects of comets such where they come from (the Oort Cloud and the Kuiper Belt), the missions used to characterize them (Deep Impact, Halley and Gitto), the comets visited (9P/Tempel 1, Borrelly and Wild 2), and how comets are thought to be the building blocks of our solar system. Lastly before taking questions from both children and adults, he showed a diagram of the robotic space craft named Rosetta which launched in March 2004, and will perform a detailed study of the comet 67P/Churyumov-Gerasimenko starting in May of 2014.

Keeping with their mission to use the David M. Brown Arlington Planetarium as a platform for STEM education, Dr. A’Hearn was the latest on a prestigious list of scientists from the world of Astronomy and Astrophysics including:
• Dr. Natalie Batalha (NASA’s Ames Research Center)
• Dr. Heidi Hammel (Association of Universities for Research in Astronomy, Inc.)
• Dr. Jared Espley (NASA Goddard Space Flight Center’s Laboratory for Planetary Magnetospheres)
• Dr. Carey M. Lisse (the Johns Hopkins University’s department of Applied Physics)

The Friends will host special events at the David M. Brown Arlington Planetarium one weekend every month until the end of the school year. For more information, visit their website. For the April weekend, no lecture or shows will be featured at the Planetarium, though Friends be present at the USA Engineering and Science Festival.

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