An annular solar eclipse occurred at the Moon's descending node of orbit between Sunday, May 20 and Monday, May 21, 2012, with a magnitude of 0.9439. A solar eclipse occurs when the Moon passes between Earth and the Sun, thereby totally or partly obscuring the image of the Sun for a viewer on Earth. An annular solar eclipse occurs when the Moon's apparent diameter is smaller than the Sun's, blocking most of the Sun's light and causing the Sun to look like an annulus (ring). An annular eclipse appears as a partial eclipse over a region of the Earth thousands of kilometres or miles wide. Occurring about 1.3 days after apogee (on May 19, 2012, at 17:10 UTC), the Moon's apparent diameter was smaller.
The annular eclipse was the first visible from the contiguous United States since the solar eclipse of May 10, 1994 (Saros 128), and the first in Asia since the solar eclipse of January 15, 2010 (Saros 141). The path of the eclipse's antumbra included heavily populated regions of China and Japan, and an estimated 100 million people in those areas were capable of viewing annularity. In the western United States, its path included 8 states, and an estimated 6 million people were capable of viewing annularity.
The eclipse was visible in a band spanning through East Asia, the Pacific Ocean, and North America. As a partial solar eclipse, it was visible from Greenland to Hawaii, and from eastern Indonesia at sunrise to western North America at sunset.
The antumbra had a magnitude of .94, stretched wide, and traveled eastbound at an average rate of per second, remaining north of the equator throughout the event. The longest duration of annularity was 5 minutes and 46 seconds, occurring just south of the Aleutian Islands. The eclipse began on a Monday and ended on the previous Sunday, as it crossed the International Date Line.
The annular eclipse commenced over the Chinese province of Guangxi at sunrise, at 6:06 a.m. China Standard Time. Travelling northeast, the antumbra of the eclipse approached and passed over the cities of Macau, Hong Kong, Guangzhou, and Xiamen, reaching Taipei by 6:10 a.m NST. After crossing the East China Sea, it passed over much of eastern Japan, including Osaka and Tokyo at 7:28 a.m and 7:32 a.m JST respectively, before entering the Pacific Ocean. The penumbra of the eclipse was visible throughout Eastern Asia and various islands in the Pacific Ocean until noon.
The path of the antumbra over highly populated areas allowed at least an estimated 100 million people to view annularity. Because the eclipse took place during the summer monsoon season in Southeast Asia, viewing conditions were not ideal in some areas, including Hong Kong.
After traveling approximately 4,000 miles (6,500 kilometers) across the Pacific Ocean, the antumbra entered North America between the coastlines of Oregon and California, reaching the coastal city of Eureka, California at 6:25 p.m PDT. After passing over Medford, Oregon and Redding, California, it had reached Reno, Nevada by 6:28 p.m PDT. The eclipse continued to travel southeast, passing 30 miles (48 km) north of Las Vegas, Nevada, over St. George, Utah, and reaching the Grand Canyon by approximately 6:33 p.m MST. After passing over Albuquerque, New Mexico and Lubbock, Texas, the eclipse terminated above central Texas at sunset, 8:38 p.m. CST. An estimated 6.6 million people lived under the path of the antumbra. The penumbra was visible throughout most of North America, including the islands of Hawaii.
Shown below are two tables displaying details about this particular solar eclipse. The first table outlines times at which the Moon's penumbra or umbra attains the specific parameter, and the second table describes various other parameters pertaining to this eclipse.
This eclipse is part of an eclipse season, a period, roughly every six months, when eclipses occur. Only two (or occasionally three) eclipse seasons occur each year, and each season lasts about 35 days and repeats just short of six months (173 days) later; thus two full eclipse seasons always occur each year. Either two or three eclipses happen each eclipse season. In the sequence below, each eclipse is separated by a fortnight.