Fast enough to escape earth's gravity and begin the shuttle era.

使其能足够快的速度逃离地球引力，从此开始航天飞机时代。

Plants have evolved over millennia using the strong gravity on Earth.

利用地球上的强大引力，植物已经进化了千年。

So, they escape Earth's gravity and drift off into space.

因此，它们逃离地球引力，漂向太空。

The Moon continues on its gravitational dance with Earth, swinging around its orbit.

月球继续与地球引力共舞，绕其轨道旋转。

Jupiter's tides are hundreds of times stronger than Earth's, so no surprise there.

木星的引力潮比地球的强，所这并不奇怪。

Rockets must travel at least 25,000 miles an hour to escape Earth's gravity.

为了逃离地球的引力，火箭必小时至少2.5万英里的速度飞行。

The gravity of earth is what makes flames rise and look like they do.

地球的引力使火焰升起，呈现出我们看到的样子。

A spacecraft and basically everything else on Earth is held down by Earth's gravity.

地球上几乎所有的物体都受到地球引力的压制。

That is a place where the gravity of the sun, moon and Earth are balanced.

那是一个太阳、月球和地球引力平衡的地方。

If we mess up the earth gravity assist, we die.

如果地球引力助推搞砸了，我们会死。

That's right. We bring him in too late, and he's pushed out of Earth's gravity.

没错。如果减速变轨的时间太迟，舱体将脱离地球的引力范围。

It has gravity, but much less than the Earth because it's less massive.

它有引力，但因为它的质量比地球小，引力也就小得多。

This is a point where the gravitational forces of the sun and Earth balance each other.

太阳和地球的引力在这里达到平衡。

Others thought the moon formed elsewhere in the solar system and was captured by Earth's gravity.

其他人认为月球形成于太阳系的其他地方，并被地球引力捕获。

Say you increase the size of Earth, so Earth's gravitational constant increases.

假设你增加了地球的大小，地球的引力常就会增加。

Elsewhere study finds that spaceflight may pose health risks to anyone spending time beyond earth's gravity.

其他地方的研究发现，太空飞行可能会给任何在地球引力之外度过时间的人带来健康风险。

Gravity may be weak here on Earth, but it's not so weak across the cosmos.

地球上的引力也许的确微弱，但放眼宇宙，情况并非如此。

The gravitational effect of the Moon keeps the degree of tilt on the Earth's rotational axis constant.

月球的引力使得地球的自转轴倾斜保持在一定的角度。

Even the Moon's low gravity, just one sixth of Earth's, could present a hazard to a tourist.

甚至月球的低引力只有地球的六分之一，对旅游者是个冒险的举动。

We learn at school that we're constantly pulled down by Earth's gravity and that's why things fall.

我们在学校里学过，我们不断地被地球引力拉下，这就是物体下落的原因。