Photo from January 15, 2000 showing a combination of three separate photographs, the various stages of an annular solar eclipse seen over Anuradhapura, Sri Lanka. (Eranga Jayawardena/AP)

The moon crosses in front of the sun, handing sky gazers an annular eclipse that starts Monday and ends on the previous Sunday, according to NASA and noted eclipse expert Fred Espenak. This will be the first solar eclipse visible in 18 years in the contiguous 48 states.

What? The eclipse starts on Monday and ends the previous Sunday? Yes, indeed.

Turning back the clock

First, the other side of the world will enjoy the solar eclipse – an eclipse just a smidgen shy of totality – that begins on Monday, May 21 in eastern China, runs through Japan, curves toward the Aleutian Islands, crosses the International Date Line, and then ends in the evening, just before sunset, on Sunday, May 20 in the western and southwestern United States - in a swath (about 185 miles wide) from Medford Oregon to Lubbock, Texas.

Those outside of this narrow path – in the western and Midwestern United States – will see a partial eclipse at sunset.

The eastern United States – including Washington, D.C. – won’t be able to see it.

Science@NASA has created a short, amazing video that explains the celestial mechanics of this eclipse. It is available on YouTube, or watch below:

The U.S. path


Via NASA: “The “path of annularity” is a strip about 300 km wide and thousands of km long. In the United States, the afternoon sun will become a luminous ring in places such as Medford, Oregon; Chico, California; Reno, Nevada; St. George, Utah; Albuquerque, New Mexico, and Lubbock, Texas.

For skywatchers in the United States, the annular eclipse’s shadow – called the “antumbra”– first passes south of the Aleutians. The antumbra makes landfall along Oregon/California border at 6:23 p.m. PDT.

Espenak says that Redding, Calif. is to enjoy an annular phase lasting over 4 minutes, starting at 6:26 p.m. Central Nevada, southern Utah, and northern Arizona are all within the annular path, he says.

When the antumbra reaches Albuquerque, N.M., at 7:34 p.m. MDT, the event lasts over four minutes, but the Sun’s altitude has sharply dropped to the horizon. The event ends just as it reaches the Texas Panhandle.

Viewing advice

An annular eclipse is different from a total eclipse, in that the moon doesn’t quite cover the entire sun’s disk. So instead of a (dull) ring of totality, we’re left with a thick, shining ring - sometimes known as a “ring of fire”. Please take caution and protect your eyes while viewing it. Never look directly at it with your naked eye or binoculars or a telescope. You could go blind. If you are lucky enough to view it, use indirect methods.

(The sun’s rays turn into little rings of light, according to Espenak. Find a leafy tree and look to the ground, and you’ll see the eclipse multiplied many times over. Or, criss-cross your fingers in a waffle style, allowing rays to beam toward the ground – and you will see the same shape as the eclipsed sun.)

Just like family

Eclipses arrive in families or series are called “saros” and this eclipse is part of Saros 128. The first eclipse in this series occurred on Aug. 29, 984, (Julian Calendar.) There are 73 eclipses in the series that spans from 984 through 2282. We only have 270 more years before we’re done.

The last Saros 128 solar eclipse occurred on May 10, 1994, and before that was April 29, 1976, and before that was April 19, 1956. Notice the pattern: series of solar eclipses happens every 18 years, 11 days … and 8 hours, according to Espenak. (For those precise sky gazers, that’s a cycle of 6,585.3 days.)

Saros 128 started as a series of partial solar eclipses between 984 through 1399.

The 15th century – still using the Julian Calendar – enjoyed all of the total solar eclipses in this series.

The series became annular – the moon not quite fitting the sun – on Aug. 11, 1561. Our next annular eclipse for Saros 128 will be seen on June 1, 2030.

The author, Blaine Friedlander, writes a monthly night sky column for the Washington Post

Related reading and sources

* Fred Espenak, eclipse expert, retired from NASA/Goddard Space Flight Center, from NASA web site

* Saros 128 background:

* NASA Technical Publication: “Five Millennium Canon of Solar Eclipses: -1999 to +3000” (NASA/TP-2006-214141)

* Fred Espenak’s Mr. Eclipse Web site is an excellent, educational resource :