燕山大学 刘立军 编写

This is Scientific American - 60-Second Science. I'm Steve Mirsky.

How many moons does Jupiter have? If you said four, you might be Galileo. If you said 69, you were right. Until the announcement this morning by the International Astronomical Union of the discovery of an additional 10 moons about the gas-giant planet. Bringing the currently known total to 79. That's a lot of moons.

A research team from the Carnegie Institution for Science, the University of Hawaii and Northern Arizona University was looking in 2017 for very distant objects in our solar system, well beyond Pluto. Jupiter happened to be in the same field of view, so they also looked for any as yet unknown moons. They found 12, two of which were announced last year. Confirmation of the moons required multiple observations, and those data enabled a calculation of the moons' orbits.

Nine of the dozen moons are well away from Jupiter and have retrograde orbits, meaning they go around the planet in what we'd think of as the "wrong direction". They take about two Earth years to complete their circuits.

Two new moons are closer in, go the right way, and take about an Earth year for one orbit. Those eleven moons are probably remnants of larger bodies that got broken up in collisions.

The remaining moon is less than a kilometer across, further out than the two conventional moons and has a 1.5-year orbit - and the orbit is inclined. That tilt has the weird little moon crossing the paths of those outer retrograde moons. Which means an increased likelihood of a big smash-up one day.

Depending on what survives from any such collision, Jupiter may then have even more moons. Or a couple of fewer.

For Scientific American - 60-Second Science. I'm Steve Mirsky.

Adapted from http://www.kekenet.com/broadcast/201901/577125.shtml

1. moon n. (可数名词) a natural satellite that moves around a planet other than the earth 卫星。例如：How many moons does Jupiter have? 木星有多少颗卫星？

2. Jupiter n. the largest planet of the solar system, fifth in order of distance from the sun 木星（太阳系中最大的行星）

3. Pluto n. one of a number of round objects in space that go around the sun but are not as large as planets 冥王星

4. retrograde adj. (formal, disapproving) (of an action 行为) making a situation worse or returning to how sth. was in the past 倒退的；退化的；退步的。例如：The closure of the factory is a retrograde step. 工厂的关闭是一大退步。

5. circuit n. a line, route, or journey around a place 环行；环行路线。例如：

 The race ended with eight laps of a city centre circuit. 比赛以环绕城中心跑八圈结束。

 The earth takes a year to make a circuit of (= go around) the sun. 地球绕太阳运行一周需要一年的时间。

6. remnant n. (常用复数) a part of sth. that is left after the other parts have been used, removed, destroyed, etc. 残余部分；剩余部分。(同义词) remains 例如：The woods are remnants of a huge forest which once covered the whole area. 这片树林只是剩下的一部分，原来这一带是一大片森林。

7. tilt n. a position in which one end or side of sth. is higher than the other; an act of tilting sth. to one side 倾斜；倾侧。例如：

 The table is at a slight tilt. 这桌子有点儿歪。

 He answered with a tilt of his head. 他歪着头回答。

8. weird adj. very strange or unusual and difficult to explain 奇异的；不寻常的；怪诞的。例如：

 a weird dream离奇的梦

 She's a really weird girl. 她真是个古怪的女孩。

 He's got some weird ideas. 他有些怪念头。

 It's really weird seeing yourself on television. 看到自己上了电视感觉怪怪的。

 the weird and wonderful creatures that live beneath the sea奇异美丽的海底生物

(A) 4.

(B) 10. 

(C) 69.

(D) 79.

(A) 12.

(B) 11.

(C) 9.

(D) 2.

(A) 9.

(B) 10.

(C) 11.

(D) 12.

(Q1) D。细节题。命题出处：How many moons does Jupiter have? If you said four, you might be Galileo. If you said 69, you were right. Until the announcement this morning by the International Astronomical Union of the discovery of an additional 10 moons about the gas-giant planet. Bringing the currently known total to 79. That's a lot of moons.

(Q2) A。细节题。命题出处：A research team from the Carnegie Institution for Science, the University of Hawaii and Northern Arizona University was looking in 2017 for very distant objects in our solar system, well beyond Pluto. Jupiter happened to be in the same field of view, so they also looked for any as yet unknown moons. They found 12, two of which were announced last year.

(Q3) C。细节题。命题出处：Two new moons are closer in, go the right way, and take about an Earth year for one orbit. Those eleven moons are probably remnants of larger bodies that got broken up in collisions.