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

注意，不是“一个”（an）天，而是“一”（one）。

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

几个世纪后，这个天终于被确定下来。

Scientists call this distance one astronomical unit, or AU.

科学家们将这个距离定为天，或缩写为 AU。

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

这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.

然后这边的木星到太有5 个天左右的距离，之后土星到太的距离大概有10 个天。

61 Cygni is about 720,000 astronomical units away.

61天鹅座离我们大约有72万天。

We call that one astronomical unit.

我们称其为一个天。

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

没有人有大气层高度或一个天更大的手掌。

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.

目前它离太的距离接近 140 个天，这意味着它离太的距离是地球离太距离的 140 倍。

The binary stars are separated by a distance of 97 astronomical units.

这两颗恒星相距97个天。

While the primary companions lie within two astronomical units of the star, the tertiary companions can be as far as 20 astronomical units.

虽然主要伴星于恒星的两个天内，但第三伴星可以达到 20 个天。

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距离的 138 倍。

Even the farthest planet, TRAPPIST-1h, orbits at a distance of only 0.062 astronomical units, six times closer to its star than Mercury is to the Sun.

即使是最远的行星TRAPPIST-1h，其轨道距离也只有0.062个天，水星到太的距离近六倍。

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的距离，因此四百个天大约是冥王星轨道的十倍。

It was travelling at an incredible speed of 540 million  kilometres per year, or 3.6 Astronomical Units, an astronomical unit being the distance between  Earth and the Sun.

它正以惊人的速度——每年5.4亿公里，即3.6个天——疾驰，这里的一个天指的是地球与太之间的距离。

When a comet approaches the Sun within a few astronomical units, solar heating causes the release of gases and dust from its surface, a process known as cometary outgassing.

当彗星接近太几亿公里范围内时，太的热量会导致其表面气体和尘埃释放，这个过程被称为彗星喷气。

To be  precise, X7 has grown from a width of 0.25 arc seconds in 2003 to over 0.4 arcseconds  in 2021, corresponding to a spread of around 3300 Astronomical units.

确切地说， X7的宽度从2003年的0.25角秒增长到2021年的0.4角秒以上，相当于扩展了大约3300天。

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质量的十万倍到数百亿倍太质量不等，其大小可达四百个天。