← Finding Your Way by the Stars · Lesson 2 of 3
Measure with your hand
You do not need instruments to measure the sky roughly. Hold your arm straight out: a closed fist covers about 10 degrees of sky, and the width of your little finger about one.
Sailors on the Indian Ocean used a kamal: a small board on a knotted cord. Holding the knot in their teeth and the board at arm's length, they lined its bottom edge up with the horizon and its top with Polaris. Each knot marked the star's height at a known port.
At arm's length, Polaris is about four fists above the horizon. Roughly how high is it?
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