As space shuttles zip into orbit and telescopes peer out at other worlds, Earth itself remains a mystery in many basic ways.
In an attempt to remedy that, a panel of geologists and planetary scientists announced this week the top 10 questions about our planet that linger today, which have strangely baffled humanity and researchers for hundreds of years and longer.
"We have to look to the past and ask deeper fundamental questions about the origins of the Earth and life, the structure and dynamics of planets, and the connections between life and climate, for example," said panel chairman Donald DePaolo, a University of California at Berkeley geochemist.
The panel canvassed geologists and deliberated at length to arrive at the focus on these questions:
1: How did Earth and other planets form?
Scientists are perplexed by how and why the planets formed into such distinct bodies, with only our rocky orb supporting life (as far as we know).
2: What happened during Earth's "Dark Age," or the first 500 million years after it formed?
Understanding Earth's early development would explain how the atmosphere and oceans developed. One difficulty: Few rocks from then are preserved, meaning little concrete evidence.
3: How did life begin?
In addition to rocks and minerals here, scientists are also probing Mars, where the sedimentary record of early planetary history predates the oldest Earth rocks.
4: How does Earth's interior work, and how does it affect the surface?
Scientists want to figure out more about the past and future of the constant convective motion of Earth's mantle and core, which triggers volcanism, mountain building and seafloor formation.
5: Why does Earth have plate tectonics and continents?
Scientists wonder why Earth has plates, constantly on the move, and how closely tectonics are related to the abundance of water, continents, oceans and life.
6: How are Earth processes controlled by material properties?
The big movers and shakers on Earth, including plate tectonics, arise from the atomic structure and other properties of Earth materials, so scientists want to know more about these properties.
7: What causes climate to change – and how much can it change?
Deeper study of the history of Earth's climate could help scientists predict the magnitude and consequences of today's climate change.
8: How has life shaped Earth – and how has Earth shaped life?
The interactions between geology and biology are key to understanding life's role in injecting oxygen into the atmosphere, mass extinctions and the course of evolution.
9: Can earthquakes, volcanic eruptions and their consequences be predicted?
Scientists still don't know how fault ruptures start and stop, and how magma moves beneath Earth's surface.
10: How do fluid flow and transport affect the human environment?
Scientists are unclear about how fluids move underground. More knowledge about this will help with management of natural resources and the environment.
The report was requested by the U.S. Department of Energy, National Science Foundation, U.S. Geological Survey and NASA.
就在航天飛機被射入軌道,望遠鏡窺探別的世界的時候,地球本身在很多基本方面依然是一個謎團。
作為解決這個問題的嘗試之一,一個有地質(zhì)學家和行星學家組成的小組本周宣布了地球至今懸而未決的10大問題。這些問題已經(jīng)奇怪地困擾了人類好幾百年,對研究者而言,時間還要更長。
"我們必須回顧過去,在諸如地球和生命的起源、行星的結(jié)構(gòu)和動力學,以及生命與氣候的關(guān)聯(lián)等方面提出更加深刻的根本性問題。"加州大學伯克利分校地球化學家、小組主席唐納德德保羅說。
小組尋求了地質(zhì)學家們的意見,經(jīng)過深入充分的分析和考慮之后,總結(jié)出來下列問題:
1、地球以及其它行星是如何形成的?
科學家疑惑不解行星如何以及為何會成長為一個個如此獨特的天體,而只有我們腳下的大石球才能支持生命(僅就目前所知).
2、地球的"黑暗時代",或者說形成后5億年內(nèi)發(fā)生了什么?
了解地球的早期演化可以解釋大氣層和海洋的發(fā)展變化。難點是:當時的巖石很少有留到現(xiàn)在的,這意味著缺乏具體的證據(jù)。
3、生命是如何起源的?
科學家不光在探測地球上的巖石和礦物,還在探測火星。火星上的星球早期沉積物比地球上最老的巖石還要早。
4、地球內(nèi)部是如何運行的,又是如何影響地表的?
科學家希望對地幔及地核恒久不變的流動的過去和未來有更多了解,正是這種運動觸發(fā)了火山活動、造山運動和海床的形成。
5、地球為什么會有板塊和大陸?
科學家希望知道為什么地球會有不斷運動著的板塊,以及地質(zhì)構(gòu)造與水量、大陸、海洋和生命的聯(lián)系有多緊密。
6、物質(zhì)的性質(zhì)是如何控制地球的演進過程的?
地球上規(guī)模巨大的運動和變化,包括板塊漂移,無一不可歸因于地球物質(zhì)的原子結(jié)構(gòu)和其他性質(zhì),因此科學家希望更加了解這些性質(zhì)。
7、什么引起了氣候的變化--變化的規(guī)模能有多大?
對地球氣候史的深入研究可以幫助科學家預測當前氣候變化的規(guī)模和后果。
8、生命如何塑造了地球--地球又如何塑造了生命?
地質(zhì)學和生物學的交匯是了解生命在向大氣注氧的過程中起到的作用、大規(guī)模滅絕和進化歷程等問題的關(guān)鍵。
9、地震、火山爆發(fā)及其后果可以被預測么?
科學家們依然不了解斷層斷裂是怎么發(fā)生和結(jié)束的,巖漿又是如何在地下運行的。
10、液體的流動和搬運作用怎樣影響了人類的環(huán)境?
科學家們不了解液體怎樣在地下流動。這方面更多的了解有助于管理控制自然資源和環(huán)境。
該報告乃是應(yīng)美國能源部、國家科學基金會、美國地質(zhì)調(diào)查局和國家航空航天局的要求而編制。