VOA慢速英语--美国国家航空航天局展示木星的构成

NASA's Juno Spacecraft Shows the Makeup¹ of Jupiter

Scientists are finding that the inside of Jupiter is just as interesting as the part of the planet’s atmosphere that we can see.

At the center of the planet is a liquid mixture of the elements hydrogen and helium. Scientists say large atmospheric² jet streams and unusual gravitational qualities also exist.

Scientists have been closely studying information sent back to Earth from NASA’s Juno spacecraft. It has been orbiting the solar system’s largest planet since 2016.

Juno is providing researchers with what they called a new understanding of Jupiter’s structure.

Until now, scientists have had little information about what is below Jupiter’s thick red, brown, yellow and white clouds.

“Juno is designed to look beneath these clouds,” said Yohai Kaspi. He is a planetary science professor with the Weizmann Institute of Science in Israel. Kaspi led part of the research using Juno’s new measurements of Jupiter’s gravity.

Luciano Iess is an aerospace³ engineering professor at Sapienza University of Rome. He also led part of the research.

“On Jupiter, a gaseous⁴ planet without a solid surface, we can only gather information from orbit,” he said.

Jupiter is called a gas giant planet. Unlike Earth and Mars which are rocky planets, Jupiter is about 99 percent hydrogen and helium. Information sent by Juno showed that deeper under the surface, Jupiter’s gas turns into a hot, dense⁵ metallic⁶ liquid.

The scientists said Jupiter’s jet streams form stripes around the planet moving about 3,000 km below the cloud tops. Deep inside, the planet is made of a liquid hydrogen and helium mixture that turns as if it were a solid body.

Planetary scientist Tristan Guillot of the Université C?te d’Azur in Nice said the very center may be made of high-pressure and high-temperature rocks and perhaps water. He added, “but it is believed to be fluid as well, not solid,”

Juno showed a small but important asymmetry⁷ between the gravitational field of Jupiter’s northern and southern halves. Kaspi said this difference is driven by the large jet streams.

The deeper the jet streams go, the more mass they contain, causing a strong effect on Jupiter’s gravitational field, he said.

The research was published in the journal Nature.

Jupiter, the fifth planet from the sun, is much larger than the solar system’s other planets, measuring about 143,000 kilometers around at its equator.

The planet is big enough for 1,300 Earths to fit inside.

I’m Susan Shand.

Words in This Story

jet stream – n. a strong current of fast winds high above the Earth's surface

solar system - n. our sun and the planets that move around it

giant – n. a thing that is very large, powerful,

ionize – v. to make an atom or group of atoms that has a positive or negative electric charge from losing or gaining one or more electrons

symmetry – n. the quality of something that has two sides or halves that are the same or very close in size, shape, and position

hemisphere – n. half of the Earth

equator – n. an imaginary circle around the middle of the Earth

1 makeup   

n.组织；性格；化装品

参考例句：

• Those who failed the exam take a makeup exam.这次考试不及格的人必须参加补考。
• Do you think her beauty could makeup for her stupidity?你认为她的美丽能弥补她的愚蠢吗？

2 atmospheric   

adj.大气的，空气的；大气层的；大气所引起的

参考例句：

• Sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
• Clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。

3 aerospace   

adj.航空的，宇宙航行的

参考例句：

• The world's entire aerospace industry is feeling the chill winds of recession.全世界的航空航天工业都感受到了经济衰退的寒意。
• Edward Murphy was an aerospace engineer for the US Army.爱德华·墨菲是一名美军的航宇工程师。

4 gaseous   

adj.气体的，气态的

参考例句：

• Air whether in the gaseous or liquid state is a fluid.空气，无论是气态的或是液态的，都是一种流体。
• Freon exists both in liquid and gaseous states.氟利昂有液态和气态两种形态。

5 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

6 metallic   

adj.金属的；金属制的；含金属的；产金属的；像金属的

参考例句：

• A sharp metallic note coming from the outside frightened me.外面传来尖锐铿锵的声音吓了我一跳。
• He picked up a metallic ring last night.昨夜他捡了一个金属戒指。

7 asymmetry   

n.不对称；adj.不对称的，不对等的

参考例句：

• These bands must introduce longitudinal asymmetry in the planetary albedo.这些云带必定引起行星反照率的经向不对称性。
• In any event the asymmetry is clear enough.总之，不对称是非常明显的。