To: WSFAlist at keithlynch.net Date: Mon, 15 Mar 2004 17:59:34 -0500 Subject: [WSFA] Marsden weighs in From: ronkean at juno.com Reply-To: WSFA members <WSFAlist at keithlynch.net> <http://reuters.com/newsArticle.jhtml;jsessionid=G1AWP2DWEFC5UCRBAEKSFFA? type=scienceNews&storyID=4571813> Excerpt: Sedna is part of the solar system, but that doesn't mean it's a planet, according to Brian Marsden, director of the Minor Planet Center of the International Astronomical Union. "I think it would be misleading to call it the 10th planet," Marsden said in a telephone interview. "Just as I think it's misleading to call Pluto the ninth planet." To be called planets, astronomical objects must be a certain size, and Pluto is at the lower limit of planetary dimensions, Marsden said. They also must "participate" in the events of the solar system, and there again, he feels Pluto does not qualify -- its orbit is neither circular nor in the same plane as the other planets. Since Sedna is smaller and far more eccentric in its path than Pluto, Marsden questioned its potential planetary status. . ________________________________________________________________