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Four times a year, Ghez focuses the telescope on the stars of the very heart of our Milky Way. She is looking for the telltale high speeds that reveal the presence of a black hole. The center of the M
超大质量黑洞
In every galaxy scientists looked at, they found evidence for a supermassive black hole. NGC 3115 NGC 3377 NGC 3379 In M31 and M32 In total there is probably 20-30 or so black holes that have been fou
超大质量黑洞
By measuring how fast these stars were moving, he could prove if there really was a black hole at the center of an active galaxy. I picked a galaxy nearby which is called NGC 1068, an active galaxy, w
超大质量黑洞
Heres what scientists think happened, oh, about a hundred million years ago. There was this three-star system. The three linked stars were strolling through the galaxy but got too close to the giant black hole at the center. The hole swallowed one of
Scientific American(七)月
The first step is to try to really understand the enemy. Poor little bee. So Jean, where is it on this bee that? Ok. I think if you looked even with a naked eye. Just to the side of the abdomen. Yes, oh, on the belly there. That grape red colored. Ok
探索与发现2013年
台湾籍旅美老师今天交给我们的句子是： A special region in the center of our brain acts as our master biological clock. Light sensitive cells in our retinas feed signals deep into that brain region, training neurons to sync up with Ea
留美老师带你每日说英文