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What Counts As Cosmic Dust
- Cosmic dust refers to extraterrestrial particles (mostly from comets or asteroids) that land on Earth and are studied by scientists.
- Scientists call them micrometeoroids in space and only 'cosmic dust' once recovered on Earth.
Tiny Grains, Constant Rain
- Dust grains under 2 millimetres that enter Earth's atmosphere are classed as micrometeorites and can reach the ground as cosmic dust.
- The Earth sweeps through a tenuous zodiacal cloud, so cosmic dust constantly lands on us.
How Much Space Dust Lands Here
- About six micrometeorites arrive per square metre of Earth's surface each year, so roofs and clothes collect cosmic dust.
- Cosmic dust is ubiquitous but vastly outnumbered by terrestrial dust in most environments.