Rounding Winter’s Bend

It’s counter-intuitive during these long, cold nights of winter, but early January brings the earth its closest to the sun in its annual orbit. Wednesday the second marked the actual point of perihelion, when we were two percent closer to the sun than usual. Earth’s orbit is not quite circular but rather egg-shaped, which creates a difference of a little more than 3 million miles from perihelion to aphelion — our farthest point from the sun — in July. That difference, however, is nowhere near enough to determine our weather and seasons, which are fully a result of earth’s 231⁄2-degree tilted axis.
    While we’ll have to wait for the return of warmer weather, we’re already rounding one of winter’s corners. This Friday marks our latest sunrise, at 7:25am, more than two weeks after the shortest day of the year on solstice. And the earliest sunset preceded solstice by the same amount. Once again, earth’s tilted axis and its elliptical orbit are two of the culprits for this discrepancy. Another is our proximity to the sun, which speeds up earth’s spin, actually shortening our days this time of year by about 30 seconds a day over the course of several weeks.
    Friday’s last-quarter moon rises around 11pm and is high in the south as dawn approaches Saturday morning. Look for blue-white Spica just a few degrees below the moon and golden Saturn trailing farther still. The next morning before dawn, Spica is to the upper right of the moon with Saturn off to its left.
    Early Monday the waning crescent is in the constellation Libra near its second-brightest star Zubenelgenubi. Some viewers see a greenish hue in this star, the only one so-colored. What about you? Tuesday and Wednesday before dawn the moon is near Antares. Early birds Thursday the 10th should look low in the southeast before sunrise for the last sliver of this moon a fraction of a degree from brilliant Venus.