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Stellar rhythm

The cosmos sings. You just have to know where to tune in to the song.

This is a perfect month to explore the rhythms of the sky. They’re now blazing like neon, even if most of the beats are generally unknown.

Patterns of the brightest objects — the Sun, Moon, and sometimes Venus — were used in timekeeping by all ancient peoples. The Sun reaching its daily highpoint has been called “noon” since medieval times, even if the word originally referred to 3 p.m. and literally meant “the ninth hour” (and still sounds like “nine”). The period from one solar highpoint to the next was a “day,” and when clocks arrived on the scene, they were set to the Sun. Not complicated. But there’s a wrinkle, known for centuries.

Because our planet’s orbit is elliptical and we’re closest to the Sun in early January, winter’s stronger solar gravity whips Earth around. So we now travel our curvy path 1 km/s faster than in the summer. As a result, during winter months, the direction toward the Sun changes faster than usual on successive days. Earth must rotate 8 seconds longer than average in order for you to again face the noonday Sun.

This extra daily time adds up so that now in February, our clocks are 14 minutes out of sync with the Sun’s position. The Sun is at its most delayed direction of the year, and it arrives at its daily highpoint at 12:14 p.m. instead of 12:00.

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