Mars and Earth have orbits which change with time.
火星和地球的轨道随着时间而发生改变。
In molecular orbital theory, we named orbits based on their symmetry.
在分子轨道理论中，我们基于轨道的对称性给它们命名。
They will likely then travel close enough to neighboring planets to disturb their orbits also.
然后，它们很可能会飞得离邻近的行星足够近，从而扰乱它们的轨道。
Let's continue our discussion now by talking about orbits, especially those of the so-called periodic-orbit comets.
现在我们继续讨论，谈谈轨道，特别是那些所谓的周期轨道彗星。
Astronomers suspect that pairs of planets also engage in this slingshot activity, leaving them in disturbed, elliptical orbits.
天文学家怀疑成对的行星也参与了这种弹弓活动，使它们处于不规则的椭圆轨道上。
In any given year, about a dozen known comets come close to the sun in their orbits, the average person can't see them all, of course.
在任何一年中，大约有十几颗已知的彗星在其轨道中接近太阳。当然，一般人看不到所有的彗星。
The orbits of Mercury, Venus, Earth, Mars, Jupiter and Saturn fit neatly into this pattern; Uranus, discovered in 1781, also obeyed the law.
水星、金星、地球、火星、木星和土星的轨道恰好符合这种模式；1781年发现的天王星也同样符合该定律。
Comets formed in circular orbits but were gravitationally flung into their present-day elliptical orbits when they ventured too close to planets.
彗星在圆形轨道上形成，但当它们冒险太接近行星时，就会被引力抛入现在的椭圆轨道。
They can attain more distant orbits; NASA plans for most of its future earth escaping payloads (to the moon and Mars especially) to carry CubeSats.
它们可以到达更远的轨道；美国国家航空航天局计划在其未来的大部分发射任务（尤其是去月球和火星的）中携带立方体卫星。
The nearly circular orbits of planets in our solar system led scientists to expect that planets around other stars would also reside in circular orbits.
在我们的太阳系中，行星的轨道几乎是圆形的，这使得科学家们预测，其他恒星周围的行星也会位于圆形轨道上。
As Europa orbits its planet, however, it flexes due to the gravitational tug-of-war between it, its sister moons, and Jupiter.
然而，当木卫二绕其行星运行时，由于姊妹卫星和木星之间的引力拉锯战，它会弯曲。
The most complex engineering project ever attempted has created an enormous set of interlinked modules that orbits the planet at more than 27,000 kilometres per hour.
有史以来最为复杂的工程项目创造了一组巨大的相互连接的模块，其以每小时27000公里的速度绕地球运行。
The Earth orbits in an ellipse.
地球沿椭圆形轨道运动。
Now, circular orbits are special.
圆形轨道非常特殊。
So, orbits in general are ellipses.
所以，轨道总体上说是椭圆的。
它绕着一颗红矮星运行。
In comparison, the Earth orbits at just 1 AU.
相比之下，地球轨道只是一个天文单位。
Dr Bottke has been tracking the orbits of asteroids.
伯克(Bottke)博士一直在追踪小行星的运行轨迹。
It doesn't simply orbit the nucleus, but as it orbits it spins.
它并不只是简单地绕原子核旋转，而是同时进行公转和自旋。
Hayabusa was launched in 2003 and matched orbits with Itokawa in 2005.
“隼鸟”号飞船则是在2003年发射升空，到2005年与Itokawa小行星的轨道同步运转。
Their orbits bring them together with a minimum distance of about 200m.
他们轨道之间最小距离约200米。
Astronomers had thought that the orbits of the planets were predictable.
天文学家早就认为，几大行星的轨道是可以预测的。
But XO-3b orbits with a crazy tilt of 37 degrees from its star's equator.
但是XO - 3b的运行轨道却与母星赤道呈异常倾斜的37度角。
The Hubble telescope orbits about five hundred fifty kilometers above Earth.
哈勃望远镜轨道位于地球上方550公里左右。
They also have much shorter orbits, ranging from 3.3 to 4.9 terrestrial days.
它们的轨道也更短，从3.3到4.9天。
We'll talk about this much later when we deal with orbits and with Kepler's Law.
在谈到轨道和开普勒定律时，我会详细介绍这一点的。
Like our solar system, the planets around Gliese 581 have nearly-circular orbits.
Gliese 581周围的行星拥有同太阳系的行星一样类圆形轨道。
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