Britannica Sources used in this answer

Why do scientists disagree about how chondrules formed?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Meteorite The Hoba meteorite, lying where it was discovered in 1920 near Grootfontein, Namibia. The largest meteorite on Earth and an iron meteorite by classification, it consists of a nickel-iron alloy and is estimated to weigh about 60 tons.

Scientists agree that chondrules formed as dispersed molten droplets that solidified and aggregated in the early solar nebula before planets were created. Evidence from their texture and crystal structure indicates they underwent "flash" heating to temperatures between 1,400 and 1,800 °C, followed by rapid cooling.12

Despite over a century of research, there is no consensus on the specific mechanism that caused this heating. Several hypotheses have been proposed, including:12

Electrical discharges3
Shock waves3
High-velocity collisions between molten asteroids13
Outflows associated with the early active Sun3

The lack of a definitive explanation persists because the formation process appears to have been localized and occurred multiple times, yet no single model has successfully accounted for all observed characteristics. Furthermore, determining the precise ages of chondrules is difficult, as it remains unclear whether measured ages reflect their initial formation or subsequent reheating and alteration within their parent bodies.23