61 Cygni is about 720,000 astronomical units away.

61天鹅座离我们大约有72万天文单位。

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

注意，不是“一个”（an）天文单位，而是“一”（one）。

Scientists call this distance one astronomical unit, or AU.

科学家们将这个距离定为天文单位，或缩写为 AU。

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

几个世纪后，这个天文单位终于被确定下来。

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

这就是为什么知道天文单位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.

然后这边的木星到太阳有5 个天文单位左右的距离，之后土星到太阳的距离大概有10 个天文单位。

We call that one astronomical unit.

我们称之为一个天文单位。

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文单位还大的手。

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 个天文单位，这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.

就上下文而言， 一个天文单位是从地球到太阳的距离，因此四百个天文单位大约是冥王星轨道的十倍。