There’s something innately spooky about solar eclipses. Maybe it’s their ominous shadows, which give the look of two celestial bodies conspiring. Or maybe it’s their rarity — a reminder that we’re on a moving rock of our own that has a trajectory that we have little to no control over. The moon orbits around Earth, and the Earth around the sun, per usual. To get its eerie look, the moon sandwiches itself between the two bodies, creating a solar eclipse.
Eclipses don’t happen every month, though, because the moon doesn’t orbit in the same plane as the sun and Earth. But just last month the Solar Dynamics Observatory observed a lunar transit, which is when the moon passes in front of another body in space. Our only satellite photobombed the sun for about an hour, blotting out nearly 60 percent of the sun at its pinnacle. Such a lunar transit happens only two to three times each year.
When the moon blocks the light coming from the sun, as it did at the end of October, it casts a shadow on us. The shadow is composed of two concentric cones called the umbra (which is smaller) and the penumbra (which is larger). Anyone in the umbra sees a total eclipse, which blocks so much of the sun’s light, it looks like nighttime in a small area on Earth. Anyone in the penumbra sees a partial eclipse.
Because the sun, moon, and Earth weren’t exactly lined up, October’s wasn’t a total eclipse. Total eclipses occur every 18 months or so, on average. But those that occur in a specific location of Earth are significantly more rare, occurring nearly every four centuries on average, according to Space.com.
Another kind of solar eclipse, an annular eclipse, is when the moon is more distant from Earth on average, meaning it doesn’t block the entire view of the sun. This creates a ring of fire around the moon. The frequency of these varies, given the requirement of specific circumstances that need to occur. Finally, there’s the hybrid eclipse, which typically move from an annular to a total eclipse, then go back to annular before they end.