The shortest distance between the sun and a planet is called perihelion.

太阳和一颗行星最短的距离叫作近日点。

Aphelion is the farthest orbital point from the sun and perihelion is the closest.

Aphelion（远日点）是离太阳最远的轨道点，而Perihelion（近日点）是指最近的。

The closest point is known as perihelion and occurs around the 3rd of January.

而最近点被称为“近日点”，大约出现在1月3日。

So, at one perihelion pass, one side of Mercury faces the Sun.

所以它第一次经过近日点时，有一面面相太阳。

Then, 88 or so days later, it approaches perihelion again.

然后在88天左右之后，它会第二次靠近近日点。

However, its motion around the Sun is faster at perihelion than aphelion.

然而，它在近日点比在远日点时公转更快。

The second law tells us that the Earth moves fastest when it's closest to the Sun, or at its perihelion.

第二定律告诉我们，当地球在离太阳最近的时候，或者说在近日点，运动得最快。

At the calculated acceleration, the head of the meteor-stream must very soon pass perihelion.

以计算出的加速度， 流星流的头部必须很快通过近日点。

(Laughter) And this is essentially what that clustering in argument of perihelion was telling us.

（笑声） 这基本上就是近日点参数的聚集告诉我们的。

These objects really did all share a common value of argument of perihelion, and they shouldn't.

这些天体确实都具有共同的近日点角角值，但它们不应该如此。

When Pluto is at perihelion, closest to the Sun, it's well above the plane of the solar system, far from Neptune's orbit.

当冥王星在近日点，即离太阳最近的时候，它就在太阳系平面的上方，离海王星的公转轨道很远。

He also figured out the planet goes faster when it's at perihelion, nearer the sun, than when it's at aphelion, its furthest distance.

他还算出这个行星在距离太阳最近的近日点比在距离太阳最远的远日点时运动的速度快。

That's because if you're on the side of Mercury facing the Sun at one perihelion, the other side will face it one year later.

这是因为如果你位于水星近日点时面对太阳的一侧，另一侧在一年后才会面对太阳。

In the past decade an American astronomer has produced an alternative explanation, that the advance of Mercury's perihelion is caused by a bulge in the sun.

在过去的十年里，一位美国天文学家提出了另一种解释，即水星近日点的推进是由太阳的隆起引起的。

The Parker Solar Probe will continue flying closer to the Sun's surface until it reaches its first perihelion - the point closest to the Sun in its orbit - on November 5.

帕克号太阳探测器将继续靠近太阳表面飞行，直到11月5日达到其第一个近日点——轨道距太阳最近的一点。

A sceptic could have said 70 years ago that it matters not whether Newton is right, if all it affects is the explanation of why Mercury's perihelion is advancing.

70 年前，怀疑论者可能会说，牛顿是否正确并不重要，只要它影响的只是对水星近日点前进的解释。

This was an explanation of why each time the planet Mercury revolves round the sun, it gets a bit closer to the sun at the nearest point (its perihelion).

这解释了为什么每次水星绕太阳旋转时，它都会在最近的点（其近日点）更接近太阳。

The tides from the Sun are far stronger on Mercury when it's at perihelion, the closest point in its orbit to the Sun, than when it's at aphelion, the farthest point in its orbit.

在近日点，也就是水星与太阳距离最近处，它受到的来自太阳的引潮力比在远日点(水星轨道上离太阳最远的点)时要强烈得多。

But at perihelion Mercury's motion around the Sun actually more than compensates for its spin, so the Sun appears to stop in the sky and actually move backwards for a few days!

但是在近日点时，水星的公转比自转快得多，所以这几天太阳会在天空中静止，甚至倒退！

His joyous excitement came as he worked through the mathematics to solve a decades long puzzle - of the small advance of the perihelion of Mercury, that is, the closest point of the planet to the sun.

当他想出数学方法来解决数十年的谜团时陷入了狂喜——他计算出了水星近日点，该星球距离太阳最近的点。