from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A billion (109) years
Sorry, no etymologies found.
The trouble is that the record does not go very far backless than a gigayear, which is only a fraction of the total age of the Earth.
Before this period, more primitive procaryotic life-forms, such as bacteria with cells that are too small to contain nuclei, are now thought to have been widespread when the Earth was less than one gigayear old.
Once or twice a gigayear, it passes through the vast thick clouds that surround that region.
A kiloparsec-scale hyper-starburst in a quasar host less than 1 gigayear after the Big Bang,
In the uniformitarianism, the ghost craters are the result of impacts that occurred as much as half a gigayear before the crust-fracturing impacts that caused the lava flows.
The sun is increasing in intensity by about 6 percent per gigayear, and that doesn’t do too much for our fragile ecosystem.
So, now you’ve got yourself a bunch of massive galaxies, that in spite of being no more than 2-3 Gyr old, already finished all their star formation a gigayear previously.