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Roughly every year or two,
somewhere in the world

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the Sun appears for a few moments
as a ring of fire in the sky.

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This is called an annular solar eclipse.

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Annular comes from the Latin word annulus,
which means ring.

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An annular solar eclipse occurs
when a new Moon passes

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directly in front of the Sun, but appears
too small to cover it completely.

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But why is that?

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It's because the Moon's orbit around
Earth isn't a perfect circle,

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but rather an ellipse or slightly
oval-shaped.

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This causes the Moon to move closer to us
and then farther away

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during its month long orbit.

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When the Moon is at its closest
point called perigee,

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it appears slightly larger in our sky.

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When it's farthest from us at apogee,

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it appears a little smaller. 

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But we don't see an annular
eclipse every month.

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That's because the Moon's orbit
is also slightly

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tilted in relation
to Earth's orbit around the Sun.

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This means during most months
the Moon is either too high or too low

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to block the Sun.

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So only when a new Moon is at apogee
and passes

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directly between Earth
and the Sun do spectators on Earth

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get the rare opportunity
to see the ring of fire in the sky.

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Unlike a total solar eclipse,
when the Moon completely covers

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the Sun, during an annular eclipse
the Sun never fully disappears.

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So if you're lucky enough to be
in the path of an annular solar eclipse

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make sure to wear your solar
eclipse glasses, or use other safe

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solar filters to witness this
spectacular ring of fire

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in the sky.