太阳_综合百科_百问中文

太阳(sun)

太阳系中心的恒星。年龄约50亿年，是太阳系的主宰，占去全部质量的99%以上。每秒钟在核心以核融合将500万吨的物质转成能量并产生微中子与太阳辐射。这些能量有少量穿透地球大气提供生命所需的光和热。太阳辐射也可作为电力供给（参阅solar cell）。太阳是发光气体构成的直径139万公里球体，约为地球质量的33万倍。核心温度接近1,500万℃，表面温度约为6,000℃。太阳是一个G型（黄色）恒星，性质大约是主序星（参阅Hertzsprung-Russell diagram）的平均值。太阳在不同的纬度自转的速率不同。在两极自转一圈要36天，在赤道只需25天。光球不停运动着，太阳黑子的数量和位置随着规律的太阳周期而改变。表面的现象包括延伸进入色球与日冕、太阳闪焰、日珥与太阳风的磁性活动。对地球的影响像是极光，以及无线电波通讯和电力线路的瓦解。除了这些活动之外，太阳似乎经历数十亿年而没什麽变化。亦请参阅eclipse、heliopause。

English version：

sun

Star around which the solar system revolves. About 5 billion years old, it is the dominant body of the system, with more than 99% of its mass. It converts 5 million tons of matter into energy every second by nuclear fusion reactions in its core, producing neutrinos (see solar neutrino problem) and solar radiation. The small amount of this energy that penetrates earth's atmosphere provides the light and heat that support life. Solar radiation can also supply electrical power (see solar cell). A sphere of luminous gas 864,950 mi (1.392 million km) in diameter, the sun has about 330,000 times the mass of earth. Its core temperature is close to 27,000,000°F (15,000,000°C) and its surface temperature about 10,000°F (6,000°C). The sun, a G-type (yellow) star, has fairly average properties for a main-sequence star (see Hertzsprung-Russell diagram). The sun rotates at different rates at different latitudes: One rotation takes 36 days at the poles but only 25 days at the equator. The photosphere is in constant motion, with the number and position of sunspots changing in a regular solar cycle. Surface phenomena also include magnetic activity extending into the chromosphere and corona, solar flares, solar prominences, and the solar wind. Effects on earth include auroras and disruption of radio communications and power-transmission lines. Despite this activity, the sun appears to have remained relatively unchanged for billions of years. See also eclipse, heliopause.

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