this post is fantastic dissertation for dummies What’s the first thing that comes into your mind when you read or hear the word comet? Most people will likely think of Halley’s Comet, one of the more famous comets. (Edmund Halley was the first astronomer to predict the return of a comet in 1769, the one now named Halley in his honor. Unfortunately he died before it returned.) If one asks them to describe a comet they will tell of a star-like object with a long tail. That answer would actually be a good start. However, for many that would be the extent of their knowledge on these interplanetary visitors from the depths of our solar system. 必須 2000文字以内 [bbs:youtube:(Youtubeの動画ID)]と書くとYoutubeの動画が貼れます。(例:[bbs:youtube:OQThUAQ0UN0])