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Điền từ vào ô trống
Manned space-craft travel at speeds of almost five miles a second. But space-craft are slow..compared...with the fastest traveler in the ..known...universe-light. Scientists calculate that light travels 186000 miles a second!
Swift ....as..it is, light takes time to cross interstellar space. Light from Sirius, a neighboring star, travels for nine years to...reach...us.
Because of the time lights takes to travel the....distance....of space, it is possible to "see" an event long.....after...is has happened. In AD 1054, Chinese astronauts recorded the..appearance.... of an object that ..lit.. up the night sky. They were seeing an exploding star. Yet scientists today calculate that the stars ...exploded..... more than four thousand years ago. .....Like.... the Chinese observers, we too may "see" happening vast distances away and long before our own time.
Điền từ vào ô trống
Manned space-craft travel at speeds of almost five miles a second. But space-craft are slow..compared...with the fastest traveler in the ...observable..universe-light. Scientists calculate that light travels 186000 miles a second!
Swift ...as...it is, light takes time to cross interstellar space. Light from Sirius, a neighboring star, travels for nine years to...reach...us.
Because of the time lights takes to travel the....distance....of space, it is possible to "see" an event long.....after...is has happened. In AD 1054, Chinese astronauts recorded the...appearance... of an object that ..lit.. up the night sky. They were seeing an exploding star. Yet scientists today calculate that the stars ...exploded..... more than four thousand years ago. ....Like.... the Chinese observers, we too may "see" happening vast distances away and long before our own time.