61 Cygni is about 720,000 astronomical units away.

61天鹅座离我们大约有72万天。

Mind you, not “an” astronomical unit — “the” one.

注意，不是“一个”（an）天，而是“一”（one）。

Scientists call this distance one astronomical unit, or AU.

科学家们将个距离定为天，或缩写为 AU。

Finally, after all these centuries, the astronomical unit was nailed down.

几个世纪，个天于被确定下来。

That's why knowing the length of the astronomical unit is so important!

就是为什么知道天的长度是如此重要的原因！

Then Jupiter's right there at 5-point something, and then Saturn is about 10 astronomical units from the Sun.

然的木星到太阳有5 个天左右的距离，之土星到太阳的距离大概有10 个天。

We call that one astronomical unit.

我们称之为一个天。

No one can have a hand that's larger than the height of the atmosphere or an astronomical unit.

没有人能拥有比大气层高度或天还大的手。

It is currently almost 140 astronomical units away from our sun, meaning that it's 140 times farther away from the sun than earth is.

目前它离太阳的距离接近 140 个天，意味着它离太阳的距离是地球离太阳距离的 140 倍。

For context, one astronomical unit is  the distance from the earth to the sun, so four hundred astronomical units is  about ten times the orbit of pluto.

就上下而言， 一个天是从地球到太阳的距离，因此四百个天大约是冥王星轨道的十倍。

AU meaning astronomical unit, which is the distance between the Earth and the Sun, which means that Voyager 1 is 138 times further away from us than the Sun is.

AU 是天，是地球到太阳的平均距离（约合 1.496 亿公里），也就是说旅行者 1 号离我们的距离是离太阳距离的 138 倍。

Supermassive black holes have masses from a  hundred thousand times the mass of the sun to tens of billions of solar masses and are so big they  get as big as four hundred astronomical units.

超大质量黑洞的质量从太阳质量的十万倍到数百亿倍太阳质量不等，其大小可达四百个天。