Night Sky

By Collin O’Mara-Green

Twinkle, Twinkle, little star…

The old nursery rhyme gets at a good observation. Stars do appear to twinkle as we look up to the night sky. This variation in brightness is mainly due to our atmosphere. Earth’s atmospheric layers are always in flux, moving with wind, humidity, and temperature. This constant change causes light traveling in a straight line from distant stars to suddenly bend or change direction as it passes through the atmosphere on its way to your eyes. Sometimes brighter with less interference, sometimes dimmer with more refraction.

The same phenomena occurs when looking at the bottom of the Downie or Yuba Rivers. If the water is calm and flowing smoothly, you can clearly see the riverbed with minor distorsion. But when the waters are raging and turbulent during spring melt, the bottom appears fuzzy or not visible.

In space, the stars don’t appear to twinkle, since there is no atmosphere. Future astronauts will need a new nursery rhyme about stars!

Keep looking up!

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