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相关概念视频

Conditions on Early Earth02:06

Conditions 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.
Conditions on Early Earth02:06

Conditions 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.
Impulse01:13

Impulse

According to Newton’s second law of motion, the rate of change of the momentum of an object is the net external force acting on it. The total change in momentum between two timepoints thus depends on both the external force acting on it and the time over which it acts. Describing this mathematically, the total change of an object’s motion is proportional to the force vector and the time over which it is applied. This product is called impulse.
Additionally, it can be shown that the total...
Gravity between Spherical Bodies01:27

Gravity between Spherical Bodies

Newton's law of gravitation describes the gravitational force between any two point masses. However, for extended spherical objects like the Earth, the Moon, and other planets, the law holds with an assumption that masses of spherical objects are concentrated at their respective centers.
This assumption can be proved easily by showing that the expression for gravitational potential energy between a hollow sphere of mass (M) and a point mass (m) is the same as it would be for a pair of extended...
Gravitation01:16

Gravitation

In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down the three laws of planetary motion, explaining in detail the geometrical properties of the planetary orbits around the Sun, there was no immediate idea to discern their connection with more fundamental laws. It was Isaac Newton who, in 1665–66, figured out the connection between planetary motion, the motion of the moon around the Earth, and the...
Impact: Problem Solving01:26

Impact: Problem Solving

In an experiment conducted during a Mars mission, a rover propels a projectile with an initial velocity, and the projectile rebounds after colliding with the Martian surface. To ascertain the maximum height attained by the projectile after this collision, the known restitution coefficient and acceleration due to gravity are employed.
By designating the launch point as the origin and utilizing kinematic equations, the vertical component of the projectile's velocity at the point of impact is...

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相关实验视频

Updated: Jul 16, 2026

Laboratory Drop Towers for the Experimental Simulation of Dust-aggregate Collisions in the Early Solar System
09:44

Laboratory Drop Towers for the Experimental Simulation of Dust-aggregate Collisions in the Early Solar System

Published on: June 5, 2014

氧气同位素和月球形成的巨大撞击.

U Wiechert1, A N Halliday, D C Lee

  • 1Institute for Isotope Geology and Mineral Resources, Department of Earth Sciences, ETH Zentrum, Sonneggstrasse 5, 8092 Zürich, Switzerland. wiechert@erdw.ethz.ch

Science (New York, N.Y.)
|October 13, 2001
PubMed
概括

月球岩石显示氧气同位素比率与地球相同,支持巨大的撞击假说. 这表明原地球和撞击器Theia起源于类似的材料,没有证据表明月球撞击造成同位素差异.

科学领域:

  • 太空化学 太空化学
  • 行星科学 行星科学
  • 地质化学 地质化学

背景情况:

  • 巨大的撞击假说提出,月球是由火星大小的天体 (Theia) 与原地球相撞后的碎片形成的.
  • 月球样本中的氧同位素为月球的起源及其与地球的关系提供了关键的见解.

研究的目的:

  • 在月球样本中精确测量氧同位素丰度 (16O,17O,18O).
  • 为了比较月球氧同位素组成与地球价值,以测试行星形成模型.

主要方法:

  • 使用高精度激光化技术进行氧同位素分析.
  • 分析了来自阿波罗11号,12号,15号,16号和17号任务的31个月球样本.

主要成果:

  • 所有分析的月球样本都表现出氧同位素组成,在单一的质量依赖分离线上.
  • 这条线在实验不确定性范围内无法与陆地分成线区分.
  • 没有证据表明月球上的同位素异质是由月球撞击引起的.

结论:

  • 完全相同的氧同位素签名支持巨型撞击模型,暗示原地球和Theia共享一个共同的同位素组成.
  • 这种共同的组成表明,这两颗天体都是在相似的日中心距离上形成的.

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Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas
07:54

Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas

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Scattering And Absorption of Light in Planetary Regoliths
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Scattering And Absorption of Light in Planetary Regoliths

Published on: July 1, 2019

相关实验视频

Last Updated: Jul 16, 2026

Laboratory Drop Towers for the Experimental Simulation of Dust-aggregate Collisions in the Early Solar System
09:44

Laboratory Drop Towers for the Experimental Simulation of Dust-aggregate Collisions in the Early Solar System

Published on: June 5, 2014

Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas
07:54

Experimental Methods of Dust Charging and Mobilization on Surfaces with Exposure to Ultraviolet Radiation or Plasmas

Published on: April 3, 2018

Scattering And Absorption of Light in Planetary Regoliths
11:34

Scattering And Absorption of Light in Planetary Regoliths

Published on: July 1, 2019

  • 月球撞击似乎不是月球上氧气同位素变化的重要来源.