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My Favorite Motions
I’m an observer of Earth’s orbit, my favorite motion. I do this by observing where the sun and moon rise
and set throughout the year, whether the horns of a crescent moon tilt high or low, or how high the ecliptic is. Tracking these motions has paid off at least twice: Once it made me realize that a partial lunar eclipse
would peak while the moon sets behind a high ridgeline I live under, and at 4:40 am the following morning,
I took this picture from my yard:
Perhaps I guessed and got lucky.
Regardless, understanding Earth’s orbit
offers useful tools of prediction, but
more important (the second payoff), it
pulled me into studying climate science.
Understanding Earth’s orbit is as much
a subject for climatologists as it is for
astronomers. In astronomy, detections
of exoplanets, for example, must be corrected for Earth’s motion. In climatology,
past climate change must be interpreted with regard to Earth’s changing orbit. The orbit parameters of interest
are tilt, eccentricity, and precession. Due to tugs from the sun, moon, and other planets, these parameters change
on scales of thousands of years, comparable in scale to major shifts in Earth’s climate.
ICY SCIENCE | QTR 1 2014