Five eclipses occur this year. None are total lunar eclipses, but major eclipses of the Sun occur in May (an annular visible from Australia and the South Pacific) and November (a "hybrid" visible from central Africa).

Diehard eclipse-chasers (or umbraphiles) have traveled great distances to see the last few total solar eclipses. For example, Australia was the destination of choice for November 2012's view of totality.

Unfortunately, this long-distance trend continues in 2013. A select few observers are heading to Australia in May to see an annular solar eclipse, and in November they'll go to Africa to witness a "hybrid" solar eclipse that begins as an annular but transitions to total. Meanwhile, the dearth of total lunar eclipses continues — and this year's penumbral (barely) partial events are only of academic interest.

Up to seven eclipses of the Sun and Moon can take place in one year, though the last time that happened was 1982. (The fewest possible is four.) Notably, in any given year only two annular or total solar eclipses can occur — as will be the case in 2013.

Geometry of solar eclipses

When the Moon passes directly between the Sun and Earth, its umbra (shadow cone) reaches Earth's surface and thus completely covers the Sun. The result is a total solar eclipse. But when the Moon is slightly farther from Earth, its disk appears to small to block the entire Sun, and an annular (or ring) eclipse results. Click on the image for a larger view.

Sky & Telescope diagram

A solar eclipse happens only at new Moon, when the lunar disk passes directly between us and the Sun. Conversely, a lunar eclipse occurs during full Moon, when our satellite passes through Earth's shadow. These alignments don't occur 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.)

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 shadow. If it goes all the way in, we see a total lunar eclipse that's preceded and followed by partial phases. If the Moon skims part way into the umbra, only the partial phases occur. And if its disk passes just outside the umbra, it still encounters the weak penumbral shadow cast by Earth.

Fortunately, no matter which type occurs, a lunar eclipse is observable anywhere on Earth from which the Moon appears above the horizon at that time. (But there's still an element of luck involved: December 2011's total lunar eclipse was gorgeous from Los Angeles but completely unobservable from New York.)

Total solar eclipse over China

Few events in nature offer the drama and spectacle of a total solar eclipse, as demonstrated by this one seen over China on August 1, 2008.

S&T: Dennis di Cicco

Because the Moon casts a smaller shadow than Earth does, eclipses of the Sun tightly constrain where you can see them. If the Moon completely hides the Sun, even for a moment, the eclipse is considered total. With its brilliant disk completely covered, the Sun's ghostly white outer atmosphere is momentarily revealed for anywhere from seconds to several minutes. However, this totality can only be viewed inside a narrow track or path on Earth's surface that's typically only about 100 miles (160 km) wide. Outside of that path, about half the world is able to watch a partial eclipse as the Moon obscures a portion of the Sun.

Occasionally the Moon passes directly in front of the Sun but doesn't completely cover it. This circumstance is known as an annular eclipse, so-called because you can see a ring, or annulus, of sunlight surrounding the lunar disk. But an annular's path is likewise narrow, and outside of it observers see only a partial cover-up.

Below are brief descriptions of this year's eclipses of the Sun and Moon. You'll find more details for the two solar eclipses on this website and in Sky & Telescope magazine as the date of each draws near. Times are in Universal Time (UT) except as noted.

April 25: Partial Lunar Eclipse
This is the first cover-up of the year, but it's almost deceptive to call April's event a partial eclipse. Only about 1% of the Moon's disk (a tiny bite only 0.5 arcminute deep) manages to slip into Earth's umbral shadow. That passage lasts for just 27 minutes centered on 20:08 UT, though before and afterward some dusky penumbral shading should be evident along the northern limb. In any case, the timing favors the Eastern Hemisphere — this event is not visible from North America.

Path of May 2013's annular eclipse

The dark strip shows where you need to be positioned in order to witness an annular eclipse of the Sun on May 10, 2013. Click here for a larger version.

NASA / F. Espenak

May 10: Annular Solar Eclipse
Just as in 2012, May features an annular eclipse of the Sun. However, unlike last year's, no one in North America gets to see it. As the map here shows, the track of annularity crosses the vast South Pacific Ocean and makes landfall in only a few places. Many in northern Australia and its Cape York Peninsula are positioned to see this ring eclipse, and so too will islanders in Papua New Guinea, neighboring Choiseul, and Tarawa in the Republic of Kiribati.

Elsewhere in Australia, as well as in Indonesia and (barely) New Zealand, there'll be a partial eclipse. For example, at 22:57 UT (not long after sunrise), those in Sydney can look forward to seeing nearly a third of the Sun covered. The Moon's biggest bite is about the same extent as seen from Honolulu in late afternoon (1:48 UT).

May 25: Penumbral Lunar Eclipse
Two weeks later the Moon has moved halfway around its orbit, and an extremely shallow penumbral lunar eclipse occurs. Just 0.5 arcminute of the lunar disk slips into the penumbra, making this event essentially unobservable. But the Moon is well positioned for the Americas, so if you want to try look along the southern limb at 4:10 UT.

One noteworthy aspect of this event is that it's the first of 71 lunar eclipses in a long-running sequence designated saros 150 that will occur through the year 3275. Here's more infomation on saros cycles and saros 150 in particular.

October 18: Penumbral Lunar Eclipse
Another barely-there lunar eclipse occurs five months later, this time favoring truly devoted eclipse-watchers in Europe and Africa. The Moon slides halfway into the penumbra, just enough to perhaps tinge its southern limb with dusky shading. Mideclipse occurs as 23:50 UT.

Path of November 2013's hybrid solar eclipse

The eclipse on November 3, 2013, begins as an annular event (far-left end of green line) but quickly becomes a total solar eclipse as the Moon's umbra crosses the Atlantic Ocean and central Africa. Click on the image for a larger version.

Sky & Telescope illustration / source: F. Espenak

November 3: Annular/Total Solar Eclipse
Syzygially speaking, the year's big event comes on November 3rd — and it's a rare "hybrid" solar eclipse. When the Moon goes directly across the Sun's face, our satellite is typically either close enough to us to cover the solar disk completely (yielding a total eclipse) or too far away to cover it all (resulting in an annular eclipse). But on November 3rd both conditions are met.

The eclipse begins as annular in the western Atlantic, about 600 miles (1,000 km) east of Jacksonville, Florida, where the track first touches Earth's surface at sunrise. But as the shadow moves southeastward, it's also moving closer to the Moon due to Earth's curvature. Soon annularity gives way to a total eclipse, and greatest eclipse occurs about 12:46 UT at a point about 200 miles (330 km) southwest of Liberia. Some cruise ships intend to be positioned near that spot, which offers 99½ seconds of totality.

The Moon's umbral shadow finally makes landfall in Gabon (68 seconds of totality) before moving east-northeastward through Congo (51 seconds), Democratic Republic of the Congo (37 seconds), Uganda (24 seconds), northern Kenya (16 seconds), southern Ethiopia, and western Somalia, where a lucky few might see 1 second of totality at sunset. During the previous hybrid solar eclipse, in 2005, a stretch of totality was sandwiched between annular views at the beginning and end. This year's edition is especially rare because it will begin with annularity and end with totality.

A wide swath of locations in the easternmost United States, northeastern South America, the Mediterranean, and virtually all of Africa can enjoy a partial solar eclipse — weather permitting, of course. In Boston, for example, the event is already under way at sunrise and reaches its maximum (with 54% of the Sun's area covered) 50 minutes later. A similar sequence occurs for Washington, D.C., where the peak coverage is 35%. Here are meteorologist Jay Anderson's weather prospects along the path, and here is a table of partial-eclipse circumstances in various cities (note: times are UT, so adjust for your time zone).

Looking ahead, 2014 will feature total lunar eclipses on April 15th and October 8th, an annular eclipse on April 29th, and a partial solar eclipse on October 23rd.


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