Just like people, stars also have lifespan. A star keeps the same color and shape for most of its life. But when it gets very old, it swells into what is called a red giant. After reaching this stage, some stars begin to cool down and grow dim. Other stars explode into spectacular supernovas.
就像人類(lèi)一樣，星星也有平均壽命。星星的一生大多數(shù)會(huì)維持相同的顏色與形狀，但是當(dāng)時(shí)間一久，就會(huì)膨脹變成紅色的巨星，這時(shí)，有些星星的溫度會(huì)開(kāi)始下降，光度也隨之下降。有些星星會(huì)爆炸，形成壯觀的超新星。
就像人類(lèi)一樣，星星也有平均壽命。星星的一生大多數(shù)會(huì)維持相同的顏色與形狀，但是當(dāng)時(shí)間一久，就會(huì)膨脹變成紅色的巨星，這時(shí)，有些星星的溫度會(huì)開(kāi)始下降，光度也隨之下降。有些星星會(huì)爆炸，形成壯觀的超新星。