天上的星星有大有小,有亮有暗,我们肉眼能看到的,只不过是其中极少的一部分。古希腊天文学家希帕恰斯把肉眼看得见的星星分为6等:最亮的是1等,稍暗的依次为2等、3等……勉强可见的是6等。后来,为了使这种划分更精确,天文学家就用小数或负数来表示,把肉眼能够看得见的最暗的星定为6等星,比1等星还亮的称为0等星, The stars in the sky are large and small, with light and darkness, which we can only see with the naked eye, but only a very small part of them. The ancient Greek astronomer Hipparchus divided the visible stars into 6 and so on: the brightest ones are 1, the less dark ones are 2, the other 3, etc ... barely visible 6 and so on. Later, in order to make this division more accurate, astronomers use decimals or negative numbers to represent the darkest stars visible to the naked eye as a 6-star, a star that is brighter than 1,