相关概念视频
01:50Global Climate Change
Throughout its ~4.5 billion year history, the Earth has experienced periods of warming and cooling. However, the current drastic increase in global temperatures is well outside of the Earth’s cyclic norms, and evidence for human-caused global climate change is compelling. Paleoclimatology, the study of ancient climate conditions, provides ample evidence for human-caused global climate change by comparing recent conditions with those in the past.
02:06Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.
02:06Conditions on Early Earth
Around 4 billion years ago, oceans began to condense on earth while volcanic eruptions released nitrogen, carbon dioxide, methane, ammonia, and hydrogen into the primordial atmosphere. However, organisms with the characteristics of life were not initially present on earth. Scientists have used experimentation to determine how organisms evolved that could grow, reproduce, and maintain an internal environment.
01:06Tidal Forces
The origin of Earth's ocean tides has been a subject of continuous investigation for over 2000 years. However, the work of Newton is considered to be the beginning of the proper understanding of the phenomenon. Ocean tides are the result of gravitational tidal forces. These same tidal forces are present in any astronomical body; they are responsible for the internal heat that creates the volcanic activity on Io, one of Jupiter's moons, and the breakup of stars that get too close to black holes.
02:45Biological Clocks and Seasonal Responses
The circadian—or biological—clock is an intrinsic, timekeeping, molecular mechanism that allows plants to coordinate physiological activities over 24-hour cycles called circadian rhythms. Photoperiodism is a collective term for the biological responses of plants to variations in the relative lengths of dark and light periods. The period of light-exposure is called the photoperiod.
02:56The Fossil Record
The fossil record documents only a small fraction of all organisms that have ever inhabited Earth. Fossilization is a rare process, and most organisms never become fossils. Moreover, the fossil record only exhibits fossils that have been discovered. Nevertheless, sedimentary rock fossils of long-lived, abundant, hard-bodied organisms dominate the fossil record. These fossils offer valuable information, such as an organism's physical form, behavior, and age. Studying the fossil record helps...
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相关实验视频
Updated: Jul 12, 2026
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
概括
周期性彗星撞击,每3300万年和2.6亿年发生一次,与地质和生物动荡相关. 这些周期表明地球外界对地球进化和构造学的影响.
科学领域:
- 地质地质地质地质地质地
- 古生物学的古生物学
- 天文学 天文学
背景情况:
- 泛热生纪以重要的地质和生物事件为标志.
- 了解地球历史中的长期周期对于进化和地质研究至关重要.
研究的目的:
- 识别和分析罗纪时期地质和生物动荡的周期性.
- 调查这些周期性和外星现象,特别是彗星撞击之间的潜在联系.
主要方法:
- 从Phanerozoic Eon. 的地质和生物动荡数据的时间序列分析.
- 确定周期性与地球撞击坑形成周期的比较.
主要成果:
- 确定了两个主要的,稳定的长期周期:大约33+/- 3百万年和260+/- 25百万年.
- 这些周期与地球撞击坑记录的周期和阶段密切匹配.
- 这些发现表明,周期性彗星撞击与全球构造和生物进化之间存在强烈的相关性.
结论:
- 周期性彗星撞击是影响地球地质和生物历史的重要因素.
- 观察到的33和2600万年周期可能源于太阳系在其银河系轨道上与星际云的相互作用.
