The answer to the third question of "Two Poems by Guo Moruo" in Lesson 27 of the People's Education Edition Chinese Book: Observe the Cowherd and the Weaver Girl in the night sky and understand their

The answer to the third question of "Two Poems by Guo Moruo" in Lesson 27 of the People's Education Edition Chinese Book: Observe the Cowherd and the Weaver Girl in the night sky and understand their astronomy. The fairy tale of the Cowherd and the Weaver Girl crossing the river on the seventh day of the seventh lunar month is probably a household name in China. Altair and Vega are located on both sides of the Tianhe River, which are particularly conspicuous in summer nights. Can Altair and Vega really meet once a year?

Altair and Vega are two stars like the sun, and they can also glow by themselves. The official name of Altair in China is Heguji; It combines with several other stars to form a constellation called Skyhawk. The official name of Vega in China is Vega I; It and several other stars form a constellation called Lyra. The names and divisions of constellations were introduced from the west.

Altair and Vega are far away from us! Altair 16 light years, Vega 27 light years. The distance between them is also very far, which is 16 light years. That is to say, the fastest light and electricity, from Altair to Vega, have to run nonstop 16 years, not to mention other means of transportation. Suppose the Cowherd and the Weaver Girl really live on these two stars, and they want to make a phone call or send a telegram to say hello to each other. This long-distance call will take 16 years one way! It can be seen that two stars in the sky can't "meet".

In addition, the surface temperature of Altair reaches 8000 degrees Celsius, while Vega is even higher, reaching 1 1000 degrees Celsius. Vega is bigger than Altair in size. The diameter of Vega is three times that of our sun, while the diameter of Altair is 1.6 times. How can two such big stars "meet"?