This month’s sky antics are bunny-quick. Right now, the sun changes its north-south motion, or declination, at the year’s fastest rate, rising two sun-diameters higher every three days. Such a swift ascendancy explains the sun’s increasingly long path through the sky in March, and also why each day offers about three minutes more sunlight than the day before.
Celestial movement is obvious rather than conceptual. Unlike the mysterious content of dark matter or sausages, it’s in your face for ready inspection. And March offers a slew of objects whose varying motions are readily noticeable.
Take meteors, for example: their differences become apparent once you’ve observed a few. (Under ideal dark skies, that shouldn’t take long, since five or six appear per hour every night.) These fragments of asteroids or comets typically travel somewhat faster than Earth’s speed of 18.5 miles per second. However, if they’re catching up with us—as are ...
