该行星轨道的方向不断变化。
The orientation of the planet's orbit is changing continuously.
科学家仔细察看行星照片，寻找生命迹象。
Scientists are studying photographs of the planet for signs of life.
新发现的这个天体的运行轨和任何其他行星的不同。
The newly discovered world followed an orbital path unlike that of any other planet.
他提出了一个描述各行星与太阳之间距离的数学公式。
He developed a mathematical formula describing the distances of the planets from the Sun.
在我们所在的银河系中，很可能存在数以万计的行星系。
Within our own galaxy there are probably tens of thousands of planetary systems.
1664年，胡克观察到了那颗行星表面的一个微红的斑点。
In 1664 Hooke observed a reddish spot on the surface of the planet.
他们回避了在行星的排列和地球上发生的事件之间有联系的看法。
They shunned the belief that there is a link between the alignment of the planets and events on the Earth.
这些可能正在使行星变暖的气体，其重要影响将在许多年之后显现。
The gases that may be warming the planet will have their main effect many years hence.
从重量为百万分之一克的样品中提取有关行星宏观组成的信息是一个极为有趣的科学尝试实例。
Extracting information about the large-scale composition of a planet from a sample weighing a millionth of a gram was a fascinating example of scientific endeavour.
这是引力与行星的相互作用，对吧？
因此，木星行星通常被称为巨行星。
这颗行星位于天炉星座的南部。
土星之后的下一颗行星是天王星。
这些行星运动的变化，导致了气候的变化。
These changes in the planet's motions, they caused the climate to change.
相比之下，类地行星最多只有稀薄的大气层。
By comparison, the terrestrial planets have meager atmospheres at best.
然而，这些行星中有许多都离恒星太近或太远。
However, many of these planets are either too near to the star or too far away.
行星绕着太阳运转。
行星构成成分的不同是造成密度差异的主要原因。
Variations in the composition of the planets are largely responsible for the density differences.
众所周知，与其他岩石行星相比，水星的密度很高。
Mercury is known to have a high density in comparison with other rocky planets.
如果它们是行星的影子，它们就会是圆形的，对吧？
If they were shadows of the planets, they would be circular, right?
自人类诞生之初起，人们就仰望星星、月亮和行星。
Since the earliest times, people have looked up at the stars, the moon and the planets.
我们的行星地球，连同其他行星，围绕我们的太阳旋转，这就是我们的太阳系。
Our planet Earth, together with other planets, revolve around our Sun in what is called our Solar system.
根据一种假设，这颗行星的重力场会对由尘埃和气体组成的原行星盘产生牵引力。
According to one hypothesis, the planet's gravitational field tugs on the protoplanetary disk of dust and gas from which it formed.
但是，与内行星的核心不同，月球的核心几乎不含铁，而典型的行星形成物质则富含铁。
But, unlike the cores of the inner planets, the Moon's core contains little or no iron, while the typical planet-forming materials were quite rich in iron.
银行星期五下午关门，直到星期一早上才会再开门营业。
Banks closed on Friday afternoon and did not open again until Monday morning.
这是119颗太阳系外行星中的一颗。这些行星围绕除太阳外的其他星体运行。
The planet is one of 119 known extra-solar planets, objects that orbit stars other than the sun.
这些岩态行星被称为“类地行星”。
彗星在组成上与气态巨行星相似。
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