BETHLEHEM, Pa., — Brad Klein reviews upcoming astronomical highlights with Bethlehem’s "Backyard Astronomy Guy," Marty McGuire.
This week, a reminder that the winter solstice arrives just after 4 a.m. on Saturday, Dec. 21.
For observers in the northern hemisphere, this solstice marks the shortest day of the year, and the moment that days begin to grow longer, rather than shorter. For those in the southern hemisphere, the opposite is true.
The difference in the length of the day, over the course of the year, may surprise you.
In the Lehigh Valley, there will be just over 9 ¼ hours between sunrise and sunset on the day of the December solstice. That’s compared with over 15 hours when the June solstice rolls around.
The changes in the length of night and day occur because our planet’s axis of rotation is tilted relative to our orbit around the sun. And that is also what give us the changing seasons.