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A refined asteroid orbit can briefly raise its risk estimate

A shrinking range of possible paths may still include Earth, concentrating the possibilities before later measurements move the range clear of it. A changing estimate can therefore reflect improving knowledge rather than an asteroid suddenly changing course.

3–5 min

Questions you could explore

  • How would you explain a rising estimate without treating it as either certainty or an error?
  • How can a shrinking range of possible orbits overlap Earth more before later observations rule out an impact?

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Space

A crescent Moon is not a partly switched-off Moon

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3–5 min

A crescent Moon is not a partly switched-off Moon

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Space

Two eclipses, two different shadows

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5–7 min

Two eclipses, two different shadows

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Space

What can century-old photographs reveal about stars today?

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8–10 min

What can century-old photographs reveal about stars today?

Space8–10 minA star photographed on a glass plate a century ago can become a new measurement when compared with later observations. Harvard's DASCH project digitizes an astronomical plate archive, alongside dates and logbooks. Explore how calibration makes those old images useful for investigating changes across decades.

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