Origins of the solar system
Meteorites contain the oldest material in the Solar System and reveal clues to the formation of our Sun and planets.
The blue-white fireball streaked across the dark skies above northern Mexico shortly after one o'clock in the morning on February 8, 1969. Residents of the Mexican town of Pueblito de Allende watched with astonishment as the glowing object approached and, with a tremendous blast, exploded into thousands of pieces that rained down across the region.
Although no one suspected it at the time, the Allende fall would revolutionize the science of meteorites. Suddenly, scientists had two tons of a previously rare type of meteorite available for study. Allende and meteorites like it contain the oldest known material formed in the solar system-and provide clues to how our solar system evolved into the Sun, planets, asteroids and comets we know today.
Keywords: Astrophysics, Solar System--Origin, Astrogeology, Meteorites--Mexico
Before Allende fell to Earth, it probably weighed around four tons—roughly the weight of an Asian elephant.
When our solar system began to take shape some 4.6 billion years ago, the Sun and planets as we know them today did not exist.
A solar system such as our own begins when a massive gas and dust cloud collapses on itself and starts to spin.
The void of outer space is not so empty after all: the galaxies are awash in tiny mineral crystals, known commonly as dust grains.
In just a few thousand years, the solar system evolved from a collection of small particles sticking together to an assortment of larger bodies known as planetesimals—precursors of the planets.
The early solar nebula was a turbulent mixture of the chemical elements, including hydrogen, oxygen, carbon, iron and silicon.
The small particles drifting in orbit around the developing Sun were initially no bigger than grains of sand.