Secondary atmosphere
Videos
A secondary atmosphere is a planetary atmosphere that did not form directly via accretion during the formation of the planetary system. It is characteristic of terrestrial planets such as the four pla
Artist's imagination of the Archean Earth with an orange-hazed secondary atmosphere, dubbed the "pale orange dot"
The nitrogen-predominant (94.2%) secondary atmosphere of Titan, the largest moon of Saturn, which is denser than Earth's atmosphere
Hadean
Videos
The Hadean is the first and oldest of the four geologic eons of Earth's history, starting with the planet's formation about 4.6 Ga, and ending 4.031 Ga, the age of the oldest known intact rock formati
Artist's depiction of a collision between two planetary bodies, similar to the hypothesized collision between Theia and Proto-Earth
Backscatter electron micrograph of detrital zircons from the Hadean (4.404 ± 0.008 Ga) metasediments of the Jack Hills, Narryer Gneiss terrane, Western Australia