VOA科学技术2024--NASA Follows Asteroid Moving Closer to Earth from Sun's Orbit

 

Scientists have discovered a small asteroid¹ that recently moved closer to Earth's orbit. The object was first observed August 7 by two astronomers³ from Spain's Complutense University of Madrid.

The asteroid, named 2024 PT5, is believed to be about 10 meters long. It usually orbits around the sun. But Earth's gravitational forces recently pulled the object closer to our planet.

Scientists sometimes call such objects "mini-moons." This is because they behave similarly to the permanent moon orbiting Earth when they are captured by gravity. But they are much smaller and only temporarily stay in Earth's orbit.

The American space agency NASA said in a statement that 2024 PT5 is "not quite a mini-moon" because it will never be fully⁴ captured by Earth's gravity. However, it described the asteroid as "an interesting object" the agency plans to follow, or track, with radar⁵-equipped telescopes. NASA noted⁶ the traveling asteroid presented no danger to Earth.

NASA and its international partners continuously search the skies for what scientists call near-Earth objects. Such objects include asteroids⁷ and comets that come within 50 million kilometers of Earth's orbit.

The search system, called ATLAS⁸, involves four different telescopes. Two of the telescopes are based in Hawaii. Another operates in Chile and the other sits in South Africa. NASA explains that ATLAS is designed to search the whole sky several times each night looking for moving objects.

2024 PT5 was identified by the telescope observing station in Sutherland, South Africa. The discovery was made by two astronomers from Complutense University of Madrid - Carlos de la Fuente Marcos and Raúl de la Fuente Marcos. They recently described the find in the publication Research Notes of the American Astronomical⁹ Society.

The Spanish astronomers said it appeared 2024 PT5 is part of a group of near-Earth objects belonging to the Arjuna asteroid belt. The objects in this asteroid belt are believed to be "surrounding the path followed by the Earth-moon system," they wrote.

Such objects are likely more common than we think, said Richard Binzel, an astronomer² at the Massachusetts Institute of Technology (MIT). He was not involved in the latest research.

Binzel told The Associated Press, "This happens with some frequency, but we rarely see them because they're very small and very hard to detect." But he noted that in recent years, progress in space observation technologies had made it possible to identify more of these moon-like objects.

Binzel added that currently, it is not known whether the asteroid broke off from a larger asteroid. He said the space rock might even be a piece of our moon "that got blasted out." NASA said such an asteroid could have been created by our moon being struck by an asteroid a very long time ago.

One of the discovering scientists, Carlos de la Fuente Marcos, told the AP in an email that because of its size and brightness, 2024 PT5 can only be seen from Earth with special equipment.

NASA said teams at the agency's Center for Near Earth Object Studies are continually tracking the movements of 2024 PT5. The center expects the asteroid to remain at a distance about nine times farther away from Earth than the moon. Scientists say it will remain gravitationally linked to Earth until November 25.

NASA plans to use its large Goldstone Solar System Radar observer to follow the asteroid. The object is set to make another close pass of Earth in January 2025, when it should stay about five times the distance between Earth and the moon. 2024 PT5 is then expected to turn away from Earth "as it continues its orbit around the sun," NASA said.

After that, the asteroid is not expected to pass close by Earth until 2055.

Words in This Story

asteroid - n. a rocky object that goes around the sun like a planet

comet - n. an object in space that leaves a bright line behind it in the sky

frequency - n. how often something happens

detect - v. to discover or identify something, especially something that is difficult to see hear, smell, etc.

blast - n. an explosion

1 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

2 astronomer   

n.天文学家

参考例句：

• A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
• He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。

3 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

4 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

5 radar   

n.雷达，无线电探测器

参考例句：

• They are following the flight of an aircraft by radar.他们正在用雷达追踪一架飞机的飞行。
• Enemy ships were detected on the radar.敌舰的影像已显现在雷达上。

6 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

7 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

8 atlas   

n.地图册，图表集

参考例句：

• He reached down the atlas from the top shelf.他从书架顶层取下地图集。
• The atlas contains forty maps,including three of Great Britain.这本地图集有40幅地图，其中包括3幅英国地图。

9 astronomical   

adj.天文学的，（数字）极大的

参考例句：

• He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
• Houses in the village are selling for astronomical prices.乡村的房价正在飙升。