从天文学角度对“两小儿辩日”中相关问题的探析

Research on relevant questions in "two children's debate on the sun" from astronomical perspective

"两小儿辩日"中,两小儿从太阳的大小和凉热出发,辩论日出与日中太阳与观测者距离的远近。文章从天文学的角度探析了日地距离的变化,计算了距离变化对太阳视大小、地面接收太阳辐射多少的影响,结果显示距离的变化不是引起太阳视大小和冷热变化的原因。视觉因素是造成太阳早晨中午视大小不同的主要原因。地表气温的差异直接导致观测者对太阳冷热感觉的差异,而太阳高度(太阳相对于水平面的仰角)和太阳穿过大气层厚度的不同则是造成地表气温差异的主要原因。相比于其它颜色的光,红光因波长较长而被大气散射的较少,因此当太阳早晨穿过更厚的大气时,剩下红色光较多,从而造成早晨的太阳发红。

In the story of ＂two children＇ s debate on the sun＂, the sun distance to the observer was discussed by two chil- dren. In this paper, the distance between the sun and the observer in the morning and at noon is analyzed from astronomical per- spective. The distance effects on the visual size of the sun and the energy received on the earth＇ s surface is estimated. The results show that the change of the sun＇ s distance does not cause the change of the sun visual size and the feeling of the hot and cold. Vi- sion is the main factor that causes the different visual size of the sun in the morning and at noon. The feeling of hot and cold depends on the atmospheric temperature which depends on the sun altitude and the atmospheric depth. In the morning, the red light is scat- tered less than other light, so the sun looks red.