发表于2024-11-24
Earth Science pdf epub mobi txt 电子书 下载 2024
What do you think is happening in this unusual picture of
the Boston skyline? Could it be a photograph used to
advertise a science fiction movie? The caption might read
"Alien spacecraft beams a blinding ray at Boston and
paralyzes the city." Or could this be a picture of the
world s largest spotlight in action?
The light beam is not from a spacecraft or a big spotlight
It is a time exposure of the sun setting across Boston
Harbor. Instead of taking the picture in one quick shot,
the film was exposed for thirty-eight minutes. After sunset
another exposure captured the view of the lighted build-
ings. Time exposures furnish much of our information
about distant stars. This unit investigates the sun, stars,
and other parts of the universe.
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Earth Science pdf epub mobi txt 电子书 下载 2024