The science of meteors, meteorites, and impact craters — reading 4.6 billion years of solar system history from space rocks
Rock in space, sand-grain to boulder size. Most are asteroid fragments.
In spaceStreak of light when meteoroid burns in atmosphere. Called "shooting star".
In atmosphereSurviving fragment that hits Earth. Only ∼5% of meteors become meteorites.
On ground| Type | % of falls | Composition | Identification |
|---|---|---|---|
| Stony (Chondrites & Achondrites) | 94% | Silicate rock, olivine + pyroxene | Dark fusion crust, light interior, may have round chondrules |
| Iron | 5% | Iron-nickel alloy (Fe-Ni) | Very heavy, magnetic, Widmanstätten patterns when etched |
| Stony-Iron (Pallasites) | 1% | Olivine crystals in metal matrix | Most beautiful, green crystals in metal, extremely rare |
Contain chondrules — mm-sized round droplets frozen from solar nebula. Carbonaceous chondrites (e.g. Murchison) contain amino acids; building blocks of life.
India's nodal lab: Physical Research Laboratory (PRL), Ahmedabad maintains meteorite repository and classifies new falls.
1. Don't wash; note GPS. 2. Photo in place. 3. Handle with clean foil, not hands. 4. Report to PRL / Geological Survey of India. The Meteoritical Society requires witnessed fall data for naming.
Age: ∼35,000-50,000 yrs Dia: 1.8 km
Only hypervelocity impact crater in basalt rock on Earth. Saline soda lake. Formed by meteor ∼2 million tons.
Best preservedDia: 3.5 km Age: ∼165 MYA
Recognized 2020 as national geo-heritage. Near your Jaipur!
Near JaipurDia: 11 km Age: ∼2.5 billion yrs
Largest in India, one of oldest in world. Formed in Bundelkhand granite.
LargestGlobal major: Chicxulub (Mexico, 180km, dinosaur extinction), Barringer (Arizona, 1.2km).
• Magnet test • Streak test (meteorite leaves faint/no streak) • Nickel test kit (terrestrial rocks lack Ni)