But Mars is much closer than the distant stars and an extended source of light.
不过火星比遥远的恒星距离我们更近，光源也更为扩展。
Light waves, spreading out from a source, carry energy and travel to distant place.
光波从光源传播时带着能量，并能传播很远的地方。
Light waves, spreading out from a source, carry energy and travel to distant place.
光波从光源传播时带着能量，并能传播很远的地方。
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