过一年,我们就要长大一岁。可是地球呢?你知道它到底多大了吗?听起来,这是个很简单的问题,可要准确回答还真有点儿难。科学家用同位素地质测定法,找到最古老的岩石,测定地球有46亿岁了。可是,最古老的岩石是地球冷却下来形成坚硬的地壳后才保存下来的,并不是地球出世时留下来的最早证据,所以并不能代表地球的整个历史。 A year later, we will grow up one year old. But what about Earth? Do you know how big it is? Sounds like a very simple question, but it’s a bit difficult to answer accurately. Scientists use isotope geoimaging to find the oldest rocks, measuring 4.6 billion years of age on earth. However, the oldest rocks were preserved after the Earth cooled down to form a hard crust, which is not the earliest evidence left when the Earth was born and therefore does not represent the entire history of the Earth.