Even thought Friday's eclipse of the Sun is a partial solar eclipse, because it's a still a solar eclipse, the Moon has to be in the new phase - it's directly between us and the Sun. This particular solar eclipse is "annular," which indicates that at maximum eclipse, the Moon won't appear to completely cover the Sun. The Sun is 400 times larger than the Moon, but it's 400 times as far, so they look to be about the same size. Of course, the distance between the Earth and moon and between the Earth and the Sun change throughout the course of the year. Our orbit around the Sun isn't a circle and neither is the Moon's orbit around us. When the Moon is on the near side of its orbit, it appears larger than the Sun. If an eclipse occurs at that time, it'll be a total eclipse. But, if an eclipse occurs while the Moon is on the far side of its orbit, it'll appears smaller than the Sun and can't completely cover the Sun's disk. This is known as an annular eclipse. From the surface of the Earth, the darkened face of the Moon will be surrounded by a bright ring of light, the annulus. Consequently, the sky won't be completely dark.

For all of the US, this is a partial eclipse, and the annulus will not be seen. Over the eastern US, the Sun sets before the eclipse ends, and thus for us, it occurs at a very low altitude in the southwestern sky. Here are some examples of how much of the Sun's surface will appear to be missing during Friday's eclipse; for Miami, Florida approximately 54%, for Houston, Texas about 27%, and In Toronto, Ontario only 10% of the Sun's disk will be covered by the Moon. If you recall, last year there was a partial eclipse of the Sun on Christmas Day. The maximum eclipse (greatest surface area of the Sun covered by the Moon) occurred just north of Hudson Bay, and for most of the US, this Friday's eclipse won't be as impressive - not that last year's was something you would want to skip Christmas for. Unless you live in Florida, Texas or Hawaii, the chances are that you won't notice anything different on Friday.

To see the exact time of the maximum eclipse at you location, see the first web address at the end of the question. Before we go any farther, it should be pointed out that it doesn't make any difference if it's a partial, annular or total solar eclipse, do not look directly at the Sun.

The annular phase of the eclipse can only be seen from a very narrow track called the path of annularity. Over the course of 3 hours and 28 minutes, the Moon's annular shadow travels along a path nearly 13,000 kilometers long, however, it's only 124 to 177 kilometers wide. The annular path begins near the International Date Line about 3,000 kilometers northwest of the Hawaiian Islands and ends in the Caribbean Sea. It'll miss Hawaii, passing about 500 km to the south, nevertheless, the islands will be treated to a pretty deep partial eclipse, approximately 80% of the Sun's surface will be obscured.

Moving along a southeastern track, the annular path begins curving northward as it approaches the Equator. The time of the greatest eclipse will occur at 11:51:56 a.m. (local time) just half a degree north of the Equator. The duration of the annular phase will last for 3 minutes and 53 seconds. As the annular path swings to the northeast, it finally makes its only major landfall when it crosses the Central American nations of Costa Rica and Nicaragua. The Sun will stand 11° above the southwestern horizon during an annular phase lasting 3minutes and 19 seconds. Nearly 92% of the Sun will be covered by the Moon. The largest city having the most impressive view is Costa Rica's capital city of San Jose.

If you're on a boat in the near the Equator in the Pacific Ocean, you may have the best view of this eclipse (the closest land at the point where the eclipse is greatest is the Galapogos Islands), but no where on Earth will this eclipse be viewed as a total solar eclipse. Annular eclipses are pretty nifty, but they pale in comparison to total solar eclipses. The difference between an annular eclipse and a total solar eclipse is, well, the difference between night and day. For instance, even though 92% of the Sun will be obscured in San Jose, you won't be able to see any stars, you might not notice the air getting cooler, and you likely won't see birds flying off to their favorite nighttime roosting trees. All of these things typically occur during a total solar eclipse. In addition, because, the Sun's disk won't be completely covered, you won't be able to see the Sun's feathery outer corona. In short, you'll miss the majesty associated with a total solar eclipse

Is it possible the astronauts on the Space Station will be able to see a total solar eclipse on Friday? The space station orbits less than 500 km above the Earth, so if the station passed above the point of maximum eclipse at the precise moment when most of the Sun's disk was obscured, the view would at least be better than from the Earth's surface - but it would be only slightly better.

The mean distance to the moon from Earth is 384,401 km. This is the semi-major axis of its elliptical orbit. As the Moon orbits us, it's distance varies from approximately 221,000 to 252,000 miles. This 13% variation in the Moon's distance makes its apparent size in our sky vary by the same amount. The closest the Earth has been to the Moon (nearest perigee) since 1750 was 356,375 km in January, 1912. On the other hand, about the furthest (most distant apogee) we've been or will be from only natural satellite is 406,720 km in February, 2125. Note, the mean distance is not equidistant between the minimum and maximum distances. Even though the absolute extreme distances cited above are separated by 213 years, nearly every year has a perigee and apogee fairly close to the absolute limits listed above.

In 2001, the apogee occurred on January 24, when the Moon was 406,653 km distant, and perigee occurred on February 7, when the Moon was 356,853 km away. On December 14, the new Moon will be approximately 387,000 km from Earth - a little further than the mean Earth-Moon distance. The bottom line is that the Space Station would need to be on the order of several thousand km higher in order for the astronauts on board to witness a total solar eclipse.

However, there's no need to blast the Space Station into a higher orbit. A little patience would save a lot of energy. At least twice a year, the geometry between the Earth and Moon is in sync enabling some part of the Moon's shadow falls on Earth's surface. For Earth-bound residents, the next annular eclipse will occur June 10, 2002 (visible mainly over the central Pacific Ocean), and the next total solar eclipse will occur next December 4 (visible from Africa to Indonesia).

For more information, see these sites -
http://www.pa.msu.edu/abrams/SkyWatchersDiary/Diary.html
http://www.moonlightsys.com/themoon/eclipses.html