The European Space Agency's Solar Orbiter captured the first-ever images of the sun's south pole in March, which were released this week.

At precisely 5:01 a.m. ET on Thursday, the sun's rays fall directly on the equator, marking the first official day of spring. Meteorologists consider March 1 the start of spring.

The fall equinox is an important way to mark Earth's annual journey around the sun. The hours of darkness will gradually increase north of the equator until the solstice on Dec. 21, and vice versa ...