For the second time in a year, a total eclipse of the Sun is about to cross China. But unlike the Moon's hard-to-reach shadow path last August, the celestial spectacle on July 22, 2009, will darken major cities, densely populated countryside, and a vast expanse of tropical ocean. And the eclipse itself will be a monster, with totality lasting more than 6.6 minutes at maximum. That makes this the longest totality until 2132.
A total solar eclipse occurs once every year or two on average, but each is visible only from a narrow track covering less than 1% of Earth’s surface. The eclipse of August 1, 2008, was visible only from parts of the Arctic, Siberia, and central Asia. Nevertheless, thousands of enthusiasts traveled by land, air, and polar icebreaker for the chance to bask briefly in the silvery twilight glow of the Sun’s corona.
The main reason why this year's totality lasts so long is because the eclipse starts just a few hours after the Moon reaches perigee. At such a close distance, the Moon appears fully 8% larger than the Sun and casts a broader than usual shadow. At the point of greatest eclipse in the western Pacific, the path of totality is 258 km (161 miles) wide.
The umbra (dark central portion) of the lunar shadow first touches Earth at sunrise at 00:53 Universal Time in the Gulf of Khambhat off western India. The shadow takes just 8 minutes to cross India before spilling into northern Bangladesh and easternmost Nepal. A minute later the umbra engulfs most of Bhutan, while the eclipse duration on the central line crosses the 4-minute mark. The Sun’s altitude is 21°.
The shadow then crosses northern Burma, a corner of Tibet, and China’s Yunnan province. Passing through the middle of Sichuan province, the eclipse track darkens the capital city of Chengdu (2 million inhabitants, 3.3 minutes of totality), Chongqing (4.1 million, 4 minutes), and Wuhan (9.7 million, 5.5 minutes). Traveling nearly due east, the shadow track encompasses the meandering course of the Yangtze River.
Near the Pacific coast, Hangzhou's 4 million citizens experience a total eclipse lasting 5.3 minutes. The Sun’s altitude is now 55°. A minute later Shanghai, China’s largest city with 20 million people, plunges into totality for 5 minutes, though it is well north of the central line. This may be the most people that have ever been in the Moon’s shadow at once.
As it moves out over the East China Sea, the umbra sweeps over Japan’s Ryukyu Islands, then Iwo Jima and Kitaio Jima, before curving southeast across the Pacific. The instant of greatest eclipse occurs at 2:35:19 UT, when totality lasts longest: 6 minutes 39 seconds. This happens over open ocean with no land in sight.
The second half of the eclipse path crosses nothing but ocean and a few tiny islands and coral atolls among the Marshall Islands and Kiribati. The total eclipse finally ends at 4:18 UT, at sunset about 1,000 km northwest of Tahiti. The Moon’s shadow lifts off Earth and returns to space, after covering 0.7% of Earth’s surface in 3.4 hours.
Future Total Eclipses
On July 11, 2010, this part of the world will be favored with its third total solar eclipse in as many years. The track is almost entirely over the South Pacific. Easter Island and southern Chile (at sunset) offer the only landfalls. And the South Pacific also hosts the next one, on November 13, 2012.
A total solar eclipse won’t cross the Americas until August 21, 2017, when the Moon’s umbra will sweep from Oregon to South Carolina.
Novae explode without warning, and even recurrent novae are pretty unpredictable. (For instance, we've been waiting way too long for T Pyxidis to erupt again
But here's a prediction about a recurrent nova that should go off in a specific year: 2009. I've calculated that the recurrent nova U Scorpii, north of Antares and east of the head of Scorpius, should explode any month now. My "crystal ball" is based on old archival photographs and data from amateur astronomers. This brings a golden opportunity for amateurs and professionals to catch the early hours of a nova eruption and to prepare in advance for an intensive observing campaign.
"Recurrent novae" are those that have had more than one eruption observed within a century or so. Classical novae too are believed to repeat, but on timescales of perhaps 1,000 to 100,000 years; we just haven't been watching long enough to see them do it yet.
U Sco is one of the most famous recurrent novae. In quiescence it usually hovers around magnitude 17.6, but in outburst it briefly shoots up by about 8 or 9 magnitudes. In fact, U Sco is the all-time fastest nova known. Its brightening from minimum to maximum takes only about 5 hours, and its decline to two magnitudes below maximum takes about 38 hours. U Sco's last three eruptions, in 1979, 1987, and 1999, were all discovered by amateur astronomers.
Asteroid Ceres approaches Earth
February is a special occasion for the solar system's biggest asteroid. Not only is 1 Ceres making its closest approach to Earth since 1857, but it also will not get this close again for at least another millennium.
The long-term gravitational tugs of the planets conspire to modify Ceres' orbit just enough for this month's record-breaking event. Still, the difference between the asteroid's appearance now and at other favorable oppositions isn't huge. In 9 years, Ceres will be only 1.2 percent farther away.
You can follow Ceres through binoculars from your backyard. It sails through northern Leo during February, in a region without a lot of bright stars. Simply use the finder chart to pick out the pattern of nearby stars, then look for the interloper.
You may think this close approach will give you a chance to see Ceres without optical aid. You'd be right -- although not by much. At opposition, Ceres glows at magnitude 6.9 in a sparse starfield. Sharp-eyed observers under the darkest skies have seen objects this faint before. However, you'll have a better chance just 3 years from now. Ceres will then brighten to magnitude 6.7 thanks to the "opposition effect." The Sun-Earth-asteroid angle then will be closer to a straight line than during this month's slightly crooked arrangement. The better alignment in 2012 will increase Ceres' brightness more than the greater distance will decrease it.
