Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2006 July 12
日落曼哈顿
影像版权与提供：Neil deGrasse Tyson (AMNH)
说明：如果今天的天气晴朗，日落时的阳光将普照曼哈顿，而太阳会从曼哈顿每一条街道的中心线精确地落下。在纽约市，到处都是沿格子状街道排列的高耸大楼，通常最高的建物会挡到日落，这种效应让曼哈顿成为一个现代版的巨石柱群，只不过它的指向大约是东偏北30度。如果曼哈顿街道排列的指向是东西向，今天看到的效应会出现在春分 (3月21日)和秋分 (9月21日)，因为在这二天，日出和日落的方位是正东和正西。假如今天的日落被云给遮住了，请勿绝望，因为每年的5月28日和7月12日都会出现相同的景观。不论在任何情况下，千万不要直视太阳。
http://www.phys.ncku.edu.tw/~astrolab/mirrors/apod_e/image/0607/nycsunset_tyson_big.jpg
A Manhattan Sunset
Credit & Copyright: Neil deGrasse Tyson (AMNH)
Explanation: Today, if it is clear, Manhattan will flood dramatically with sunlight just as the Sun sets precisely on the centerline of every street. Usually, the tall buildings that line the gridded streets of New York City's tallest borough will hide the setting Sun. This effect makes Manhattan a type of modern Stonehenge, although only aligned to about 30 degrees east of north. Were Manhattan's road grid perfectly aligned to east and west, today's effect would occur on the Vernal and Autumnal Equinox, March 21 and September 21, the only two days that the Sun rises and sets due east and west. If today's sunset is hidden by clouds do not despair -- the same thing happens every May 28 and July 12. On none of these occasions, however, should you ever look directly at the Sun.
Tomorrow's picture: shuttle ride