Up to seven eclipses of the Sun and Moon can take place in one year, though the last time that happened was 1982, and the fewest possible is four.
That latter, minimalist mix is what’s in store for 2022, and no eclipses at all occur until the April 30th. It’s an assortment skewed toward disappearing Moons: There’ll be two total lunar eclipses — both of which will be seen well from North America — but the two solar eclipses will be just partials.
Before describing this year's individual events, let’s explore some eclipse basics.
A solar eclipse, such as the one seen coast to coast across the U.S. in August 2017, occurs only at new Moon, when the lunar disk passes directly between us and the Sun and consequently the Moon’s shadow falls somewhere on Earth’s surface
Conversely, a lunar eclipse takes place during full Moon, when our satellite passes through Earth’s shadow.
These alignments don’t happen at every new and full Moon because the lunar orbit is tipped about 5° to Earth’s orbital plane — only occasionally do the Sun, Earth, and Moon line up exactly enough for an eclipse to occur. (The technical name for that, by the way, is syzygy.) And, as the diagram above implies, those alignments occur roughly a half year apart. So since the last eclipse of 2021 occurred in early December, the first eclipse of 2022 doesn’t take place until April 30th.
LUNAR ECLIPSES
Three types of lunar eclipse are possible (total, partial, and penumbral), depending on how deeply the full Moon plunges into or near the umbra, our planet’s dark, central shadowIf the Moon goes all the way in, we see a total lunar eclipse that’s preceded and followed by partial phases. That was the case during the widely viewed event in September 2015, which marked the conclusion of a series of four consecutive total lunar eclipses in 2014–15! Such eclipse tetrads are not common — the last one occurred during 2003–04, but the next won’t begin until 2032.
If the moon ventures just partly into the umbra, as pictured above, only the partial phases occur — you’ll see some of the Moon in nearly full sunlight, and some of it steeped in the deep, red-tinged umbral shadow
And if its disk passes just outside the umbra, the Moon still encounters the weak penumbral shadow cast by Earth. A sharp-eyed observer will notice that one side of the full Moon’s disk looks a little dusky. All four of 2020’s lunar eclipses were of the penumbral variety.
Fortunately, every lunar eclipse is observable anywhere on Earth where the Moon is above the horizon. (But there’s still an element of luck involved — after all, the sky has to be clear!)
SOLAR ECLIPSES
Annular and total solar eclipses require the Moon to cross directly in front of the Sun as seen from Earth — and, as the graphic below shows, such “central” solar eclipses can only occur within a two-week-long interval when the Moon crosses the ecliptic during one of its two nodal crossings each year. However, the geometric window for partial solar eclipses is wider, roughly five weeks long.
If the Moon completely hides the Sun, the eclipse is considered total. With its brilliant disk completely covered, the Sun’s ghostly white outer atmosphere, called the corona, is momentarily revealed for durations from seconds to several minutes.
Occasionally the Moon passes directly in front of the Sun but doesn’t completely cover it. When that occurs, it’s usually because the Moon is farther from Earth than its average distance. (The Moon’s orbit isn’t perfectly circular; its eccentricity is about 5%.) This geometric circumstance is known as an annular eclipse, so-called because you can't see a ring, or annulus, of sunlight surrounding the lunar disk. Annular eclipses of the Sun occur about as often as the total ones do.
