小惑星が地球の大気によって効率的に破壊される
1Department of Earth Science and Engineering, Exhibition Road, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. p.a.bland@imperial.ac.uk
Nature
|July 18, 2003
まとめ
新しい分離した断片モデルでは,大型の石質小惑星が大気中に分解することが示されています. この研究は,小惑星が地球に衝突する割合を明らかにし,220mを超える天体の衝突は17万年に1度発生すると推定しています.
科学分野:
- 惑星科学は惑星科学である.
- 天体物理学 天体物理学
- 地質物理学 地質物理学とは地質物理学です.
背景:
- ボライドと大気の相互作用の正確なモデリングは,地球への衝突速度の予測に不可欠です.
- 以前のモデルは,しばしばインパクターを液体のようなものとして簡素化しました ("パンケーキ"モデル).
- より現実的な分離した断片モデルでは,個々の粒子の運動,空気力学,および消去を考慮します.
研究 の 目的:
- 大気とボリドの相互作用のための"パンケーキ"と分離された断片モデルを比較するために.
- 統計的に分析するには,1kmまでの鉄と石の沸騰物による大気中断を統計的に分析する.
- 地球の表面に衝突する小惑星の流れを測定する.
主な方法:
- "パンケーキ"モデルと"分離した断片"モデルの両方を用いて1,000以上のシミュレーションを実施しました.
- シミュレートされた鉄と石のボイドは,初期直径が約1kmまであります.
- 統合されたシミュレーションデータと大気前小惑星流量データ.
主要な成果:
- 分離した断片のモデルは,以前に推定されたものよりはるかに大きな石質体の大気破壊を予測しています.
- この研究は,様々な小惑星の組成と大きさの大気-ボリド相互作用の統計的イメージを提供します.
- 1,000以上のシミュレートされた衝撃のデータセットが生成されました.
結論:
- 分離した断片モデルでは,ボリデの大気圏への侵入をより現実的に評価できます.
- 小型ボリド (<1km) の地球表面衝突フルースが解明されました.
- 220m以上の小惑星は,およそ17万年ごとに地球に衝突すると推定されています.
関連する概念動画
Acceleration due to Gravity on Other Planets
The gravitational acceleration of an object near the Earth's surface is called the acceleration due to gravity. It can be measured by conducting simple experiments on Earth. However, such an experiment is impossible to conduct on the surface of other planets.
Astronomical observations are thus used to measure the acceleration due to gravity on other planets. This can be determined by observing the effect of a planet's gravity on objects close to it. The crucial factor that helps in this...
Astronomical observations are thus used to measure the acceleration due to gravity on other planets. This can be determined by observing the effect of a planet's gravity on objects close to it. The crucial factor that helps in this...
Energy of a Satellite in a Circular Orbit
Thousands of artificial satellites orbit the Earth every day at various distances from the Earth. Satellites that orbit the Earth below an altitude of 1,600 km are considered to be orbiting in low-Earth orbit (LEO). Research satellites and Earth observation satellites are usually placed in LEO, and mostly orbit the Earth in elliptical orbits. Navigation satellites are placed in medium-Earth orbit (MEO), ranging from 2,000 km to 36,000 km from the surface of the Earth. Meanwhile, communication...
Kepler's First Law of Planetary Motion
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. He formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe.
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
Escape Velocities of Gases
To escape the Earth's gravity, an object near the top of the atmosphere at an altitude of 100 km must travel away from Earth at 11.1 km/s. This speed is called the escape velocity. The temperature at which gas molecules attain the rms speed, which is equal to the escape velocity, can be estimated by using the equation for the average kinetic energy of the gas molecules. According to the kinetic theory of gas, the average kinetic energy of the gas molecules is proportional to its temperature.
Radiation Pressure: Problem Solving
The radiation pressure applied by an electromagnetic wave on a perfectly absorbing surface equals the energy density of the wave. The wave's momentum also gets transferred to the surface when an electromagnetic wave is entirely absorbed by it. The rate at which momentum is transmitted to an absorbing surface perpendicular to the propagation direction equals the force on the surface.
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per...
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per...
Microbes and Climate Change
Microorganisms are pivotal agents in Earth's biogeochemical cycles, significantly influencing climate dynamics through their metabolic activities. These microbes modulate the levels of key greenhouse gases by both contributing to and helping mitigate climate change.Microbial Contributions to Greenhouse Gas EmissionsRising global temperatures accelerate microbial metabolism, which, in turn, speeds up the decomposition of organic matter. This process releases carbon dioxide (CO₂) through...


