1:46

What is a Solstice?

What is the definition of a solstice, and when do they happen? Is the winter solstice always the first day of winter? Find out what causes these bi-annual astronomical events, as well as how they bring about the shortest and longest days of the year.
1:31

This Japanese Cave Creates a Heart Shape With Sunlight

See how sunlight creates the image of a shining heart in this cave in Japan. It happens near the spring and autumn equinoxes when the morning sunlight passes through the arch of Japan's Kameiwa Cave.

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