A partial solar eclipse will take place next week, oddly ending the day before it begins.

The eclipse will be visible, weather permitting, from northeastern portions of Asia, including all of Japan, northeastern Mongolia and China, and much of Siberia. Since these regions are located to the west of the International Date Line, the eclipse will take place Thursday, Oct. 14.

To the east of the Date Line, however, the calendar date is Oct. 13. And it will be those lucky skywatchers who live in the western half of Alaska that will be able to see the final moments of the eclipse, when it reaches a spectacular peak just as the Sun sets beyond the west-southwest horizon late Wednesday afternoon.

The eclipse will start on Oct. 14, but it will end on the previous day! [Local Viewing Times]

It is the second partial solar eclipse of 2004. In the first one, on April 19, the lower-third of Africa saw the new Moon partially eclipse the Sun.

What will happen

The dark shadow cone of the Moon is known as the umbra, and it is what can create the grand spectacle of a total eclipse. But this time, the umbra will completely miss the Earth, passing less than 140 miles (220 kilometers) above the North Pole and out into space.


Photos of Total Solar Eclipse Nov. 23, 2003

Meanwhile, the Moon's outer shadow (known as the penumbra), from where the Moon will appear to partially eclipse the Sun, will slice into a part of the Northern Hemisphere. [How Eclipses Occur]

Partial solar eclipses are usually shunned by professional astronomers because they lack the drama and beauty of a total solar eclipse. Yet the setup affords many people the opportunity to view firsthand the dark disk of the Moon crossing in front of the Sun. [Photo of a Partial Eclipse]

"A partial eclipse, whether or not it leads to totality or annularity, offers a wonderful opportunity to experience the magic of astronomy," writes Philip Harrington in "Eclipse!" (John Wiley & Sons, Inc., 1997).

The details

The point of greatest eclipse lies near the town of Kenai (southwest of Anchorage). There, 92.7 percent of the Sun's diameter will be eclipsed at local sunset.

Other Alaskan towns, including Kotzebue (91.2 percent), Nome (91.4 percent) and Bethel (92.4 percent) will also see the Sun disappear beyond the horizon while still deep into the eclipse. Because such a large fraction of the Sun will be covered by the Moon for these locations, an eerie "counterfeit twilight" may appear to fall over the landscape just prior to sunset.

Those living across the eastern half of Alaska (except the Southeast Coast) will see eclipse's opening stages up until local sunset.

This eclipse will not be visible from virtually any part of Canada (save for a fleeting glimpse for that part of the Yukon Territory immediately bordering Alaska) or any part of the 48 contiguous United States.

But for those living in Hawaii, the Moon will appear to obscure about half of the Sun's disk on Wednesday afternoon. The Moon's passage across the Sun will result in a large "bite" on the Sun's right-hand side, making for a most unusual looking tropical sunset!

Be very, very careful about the precautions for eclipse viewing. Never look at even a tiny bit of the Sun's disc unless you are using a proper filtration device, such as #14 welder's glass or aluminized Mylar plastic to protect your eyes. Eclipse glasses from reputable astronomy-product dealers are also safe. And there are other safe methods for indirectly viewing an eclipse. [Safe Viewing Techniques]

There is more in store later this month. A total eclipse of the Moon will be visible from most of the Americas and Western Europe on Oct. 27.

The next solar eclipse will be an unusual "hybrid" eclipse -- part annular, part total -- on April 8, 2005 chiefly over the Pacific Ocean. However, those living across portions of the southern and eastern U.S. will be able to see a partial solar eclipse.

Local viewing circumstances

The table below provides local viewing circumstances of the eclipse for ten cities and has been calculated by astronomer Fred Espenak of the NASA/Goddard Space Flight Center. For China, Japan and Korea, this is a late-morning to midday event occurring on Oct. 14.

For Anchorage and Honolulu, however, this is a late-afternoon/early evening event on October 13. In addition, sunset will intervene at these two locations, so the end of the eclipse will not be visible because it will occur after the Sun has set. Magnitude refers to the percentage of the Sun's diameter that will be obscured at maximum eclipse.

LOCATION

STARTS MAX MAGNITUDE

ENDS

Oct. 14

       

Harbin, China

9:21 a.m.

10:09 a.m.

20.5%

10:58 a.m.

Mukden, China

9:37 a.m.

10:08 a.m.

7.8%

10:40 a.m.

Nagoya, Japan

10:48 a.m.

11:37 a.m.

18.1%

12:27 p.m.

Osaka, Japan

10:51 a.m.

11:36 a.m.

14.7%

12:21 p.m.

Tokyo, Japan

10:45 a.m.

11:41 a.m.

24.0%

12:36 p.m.

Yokohama, Japan

10:46 a.m.

11:41 a.m.

23.4%

12:36 p.m.

P'yongyang, N.Korea

10:47 a.m.

11:14 a.m.

5.8%

11:42 a.m.

Seoul, S. Korea

10:52 a.m.

11:18 a.m.

4.9%

11:44 a.m.

Oct. 13

       

Anchorage, Alaska

5:56 p.m.

6:47 p.m. (sunset)

77.2%

- - - -

Honolulu, Hawaii

5:14 p.m.

6:06 p.m. (sunset)

48.0%

- - - -

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Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York.