What do you like doing in your spare time? dissertation formatting Scientists assume carbon dioxide, methane, ammonia, water and dust to be the constituents of this dirty snowball-like comet ISON. These elements are said to have been the elementary units of planets formed 4.5 billion years back. 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])