The Evolving Universe

Smithsonian Institution

How do we know about our Sun's early history as a protostar?

protostar inside a nebula with a planetary disk surrounding the protostar and ejected stellar material on the top and bottom of the protostar

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We can't go back in time to watch our Sun's birth, but meteorites found on Earth provide clues to its past.

The Allende meteorite, which fell in Mexico in 1969, contains refractory inclusions - clumps of dust grains formed very near the infant Sun.

But the Allende meteorite came from the asteroid belt, which is farther from the Sun than Earth.

How did the refractory inclusions get there?

A protostar - a star whose core has not yet started fusing hydrogen atoms into helium - rotates very quickly, spewing jets of hot matter from its poles. This matter ends up far from where it was formed.

Astronomers also see this process in faraway star nurseries, such as the Carina Nebula.