MAP | 地球科学，带你涨知识，学英文（系列）
Directions:
Identify the choice that best completes the statement or answers the question.
The distance from Earth to the stars is measured in
A | years
B | photons
C | quasars
D | light-years
Which galaxy do we live in?
A | Orion Galaxy
B | Milky Way Galaxy
C | Polaris Galaxy
D | Vega Galaxy
Which of the following is no longer considered a planet?A | Pluto
B | Mercury
C | Neptune
D | Uranus
解析
The correct answer is D | light-years.A light-year is a unit of distance used by astronomers to measure the distance between stars and galaxies. It represents the distance that light travels in one year in the vacuum of space. One light-year is equivalent to about 9.461 trillion kilometers (5.878 trillion miles).
正确答案是 光年。光年是天文学家用来测量恒星和星系之间距离的距离单位。它代表光在真空中一年内行进的距离。一光年相当于大约 9.461 万亿千米（5.878 万亿英里）。
The correct answer is B | Milky Way Galaxy.We live on a planet called Earth that is part of our solar system. Our solar system is a small part of the Milky Way Galaxy. The Milky Way is a spiral galaxy that contains gas, dust, and billions of stars and their solar systems, all held together by gravity.
正确答案是 银河系。我们生活在一个叫地球的行星上，它是我们太阳系的一部分。我们的太阳系是银河系的一小部分。银河系是一个螺旋星系，包含气体、尘埃和数十亿颗恒星及其太阳系，所有这些都被引力牢牢地固定在一起。
The correct answer is A | Pluto.Pluto was long considered our solar system’s ninth planet. However, in 2006, the International Astronomical Union (IAU) created a new definition for planets and decided that Pluto did not fit the bill. According to the IAU, a planet must be a celestial body that orbits the sun, is round or nearly round, and “clears the neighborhood” around its orbit. Pluto failed on the third account because its orbit overlaps with Neptune. The IAU reclassified it as a dwarf planet.
正确答案是 冥王星。冥王星曾长期被认为是我们太阳系的第九大行星。然而，在 2006 年，国际天文学联合会（IAU）制定了新的行星定义，并决定冥王星不符合标准。根据 IAU 的说法，行星必须是绕太阳运行、呈圆形或近似圆形、并拥有自己独立轨道（“清除其轨道周围区域”）的天体。冥王星在第三个条件上不符合，因为它的轨道与海王星重叠。IAU 将其重新分类为矮行星。