The formation of the earth was a process that scientists cannot be truly certain about, but with the help of evidence from other planets, asteroids, and the moon, the scientific community has begun to piece together our planet’s birth. About 4.56 billion years ago, a supernova exploded and left behind a cloud of interstellar dust and gas, which began to slowly compress (Boss, 2010). The center of the cloud became a hot, solid mass, which over time became a star, now known as our Sun. Around the star was a hot, glowing disk of particles that slowly began to cool over millions of years. Eventually, small particles of iron, silicon, magnesium, aluminum, and oxygen began to materialize from this hot disk and collisions occurred (Faure andMacDougall, 2010). Over time, the particles slammed together enough to create masses that had their own gravitational pull, called planetesimals. After many collisions, the planets known in our solar system were formed and the energy from the collisions caused the elements in the “rocks” to sort out, with iron in the center of the mass and lighter elements creating the mantle (Alden, 2010). Due to solar activity, the gases on the surface of the 4 inner planets were burned off, revealing the rocky mantle and crust. Scientists refer to this time period as the Hadean Eon, as it is the several hundred million years from the end of the formation of the planet to the formation of the oldest recognized rocks found (Taylor, 2010). It is believed that the Earth’s crust during this time was basaltic. Scientists believe that after the accretion of the Earth was almost finished, another planetesimal collided with the earth, knocking it off center and causing it to lose some mantle into the surrounding space (Alden, 2010). This mass was large enough to compete with Earth’s gravity and is now our moon.

Page by Julia Bobo

Photo credit: National Geographic Society: m200412-83-sw.jpg

Alden, A. Earth’s Formation in a Nutshell. About: Geology. Accessed January, 2010.

Boss, A.P. "Solar system", in AccessScience@McGraw-Hill. Accessed January, 2010.

Faure, G., and J. D. MacDougall, "Elements, geochemical distribution of", in AccessScience@McGraw-Hill. Accessed January, 2010.

Taylor, S. R. "Hadean", in AccessScience@McGraw-Hill. Accessed January, 2010.