首页
登录
职称英语
The search for water—and possible life—on Mars got a boost this week as scie
The search for water—and possible life—on Mars got a boost this week as scie
游客
2025-01-13
32
管理
问题
The search for water—and possible life—on Mars got a boost this week as scientists announced evidence of an ancient ocean on the planet’s northern plains.
The massive, sediment-filled basin surrounded by "shoreline-like" features was first spotted when scientists were mapping Mars’s surface using images from the late-1970s Viking missions.
The features made theories of an ancient Martian ocean quite popular—until NASA’s Mars Global Surveyor highlighted some seemingly insurmountable problems. The Arabia and Deuteronilus "shorelines" are thousands of kilometers long. But they undulate like a long wave, rising and falling in height as much as several kilometers(more than a mile)along their length. "That doesn’t seem to jibe with the idea that they are shorelines, because shorelines form at sea level," said lead author Taylor Perron, a postdoctoral fellow in Harvard University’s Department of Earth and Planetary Sciences.
But there really was an ocean there, Perron and colleagues now suggest in a finding that adds to a number of recent studies bolstering evidence of Mars’s watery past. The researchers believe that Mars’s poles, along with the axis the planet spins on, have moved about 1,850 miles(3,000 kilometers)during the past two or three billion years. The process, known as "true polar wander", can cause dramatic topographic changes in a planet’s surface—in this case making the once-flat shorelines rise and fall over enormous distances. "When the spin axis moves relative to the surface, the surface deforms, and that is recorded in the shoreline," said co-author Michael Manga, professor of earth and planetary science at the University of California, Berkeley.
On the Martian equator one finds the Tharsis rise—a massive bulge that holds the colossal volcano Olympus Mons. "The largest mountain in the solar system is sitting almost right on the equator, and that’s right where you should expect such a large surface load to be," Perron said. "That tells you that if Mars experienced any true polar wander after the creation of Tharsis, it should reorient in such a way that keeps Tharsis at the equator—a circle 90 degrees from Tharsis."
The current locations of the poles, along with calculations of their previous positions based on the deformation of the shorelines, suggest just such an alignment.
The findings are sure to spark debate among many professionals in search of a liquid "smoking gun" on the red planet. Jeff Moore, a planetary geologist at NASA’s Ames Research Center who is unaffiliated with the study, finds it plausible that early Mars had large standing bodies of water—either liquid or frozen. "But while the new study presents a possible explanation for why the shorelines don’t follow a constant contour, it’s not a conclusive one," Moore said. [br] What is the main idea of the passage?
选项
A、Evidence of an ancient ocean on Mars.
B、Researchers find out many problems related to Mars.
C、Mars has experienced a true polar wander.
D、Tharsis rise proves the existence of shorelines on Mars.
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3911113.html
相关试题推荐
Researchintoself-awarenessconsistentlyshowsthatmostpeoplethinkandsp
Researchintoself-awarenessconsistentlyshowsthatmostpeoplethinkandsp
Researchintoself-awarenessconsistentlyshowsthatmostpeoplethinkandsp
Researchintoself-awarenessconsistentlyshowsthatmostpeoplethinkandsp
Thinkgolfis【C1】______game?Thinkagain.ResearchersincludingDebbieCrews
Thinkgolfis【C1】______game?Thinkagain.ResearchersincludingDebbieCrews
Thinkgolfis【C1】______game?Thinkagain.ResearchersincludingDebbieCrews
Thinkgolfis【C1】______game?Thinkagain.ResearchersincludingDebbieCrews
Thinkgolfis【C1】______game?Thinkagain.ResearchersincludingDebbieCrews
Thinkgolfis【C1】______game?Thinkagain.ResearchersincludingDebbieCrews
随机试题
•Readthefollowingletter.•Choosethebestwordtofilleachgap.•Foreachqu
Ihavelongwantedtostartmyownbusiness,butnotuntilrecently________thec
经过了长期的缓慢发展之后,中国的城市正在突然迅速地向四面八方扩展开来。中国城市人口正在以每年7%的速度增长,而在某些大城市里则达到了每年增长10%。仅举
某企业运用提前期法来确定各车间的生产任务。装配车间(最后车间)10月份应生产10
下列各项中,属于以后会计期间将重分类进损益的其他综合收益项目有( )。 Ⅰ外
基金管理人的内部控制要求不包括( )。A.严格授权控制 B.严格控制基金财产
左边给定的是纸盒的外表面,右边哪一项能由它折叠而成?
()无法为LBS提供获取位置信息方面的技术支持。A.WCDMA B.GP
根据《企业破产法》的规定,下列有关和解的表述中,正确的是()。A.对债务人的特
某企业拟新建一项目,有两个备选方案技术均可行。甲方案投资5000万元,计算期为1
最新回复
(
0
)