If you have been watching the sunsets over the past few months, you will have noticed that they have been slowly moving north along the western horizon. Sunday, at 7:02 a.m., the sun climbed back across the celestial equator into the northern sky marking the vernal equinox and the first day of spring.
The tilt of our planet's axis causes the sun to appear to change its path across the sky as Earth orbits the sun. In the summer, the sun takes a long, high path across the sky, and we get lots of sunlight. During winter, the sun is low in the sky, and its trek from sunrise to sunset is short. On the first day of spring and fall, the sun is in the middle of the sky and rises and sets due east and west. Because daytime is about equal to nighttime, we call these days equinoxes.
The sun will continue on this northbound journey until the summer solstice June 21. After lingering at its northernmost point along the horizon, it will begin its journey southward. This journey from north to south and back to north takes 365 days, or one year.
Celebrate the arrival of spring by joining the staff of Carnegie Science Center's Buhl Planetarium and Observatory, the Amateur Astronomers Association of Pittsburgh and Kiski Astronomers Saturday and Sunday for Space Out! Astronomy Weekend.
This two-day celebration showcases the astronomy and space science that happens here at the Science Center and Western Pennsylvania throughout the year. During the weekend, you and your family can increase your awareness about the science, profession and hobby of astronomy as you check out the latest telescopes and hear about the hottest astronomical news from guest speakers. Hands-on activities also are geared for all ages and interest levels. For more information, go to www.carnegiesciencecenter.org.