The sky will get a little dark over parts of South America and the southeastern Pacific Ocean tomorrow afternoon — thanks to a partial solar eclipse. The Moon will cover part of the Sun, blocking its light.

Solar eclipses occur only at new Moon. That’s when the Moon passes between Earth and the Sun. New Moon comes about once a month, but we don’t have solar eclipses that often. That’s because the Moon’s orbit around Earth is tilted a bit. So most months, the Moon passes a little above or below the Sun — and the Sun shines on.

But if new Moon occurs when the Moon is crossing the ecliptic — the Sun’s path across the sky — then, bingo! — an eclipse. If the alignment is just right, it’s a total eclipse — the Moon covers the entire solar disk, and day turns to night. Otherwise, it’s a partial eclipse, with the Moon covering only part of the Sun.

Tomorrow’s eclipse is partial. At its peak, the Moon will cover a little more than half of the Sun. So the sky will grow dark enough for people to notice it, but that’s about all.

The eclipse gets underway at 1:45 p.m. Central Daylight Time, when the shadow of the Moon first touches the Pacific. The shadow then will move northward, covering Chile and Argentina and parts of the adjoining countries. The eclipse reaches its peak at about 3:41, and ends a couple of hours after that.

Those of us in the northern hemisphere are out of luck — we’ll miss the eclipse entirely.
 

Script by Damond Benningfield

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