Terasecond and longer

A **terasecond** (symbol:  **Ts**) is one trillion seconds. That is about 31,700 years. It can be written as **1012 seconds**.

Here is a list of time spans longer than 1 terasecond:
* 1015 seconds = 1 *petasecond* = 31.7 million years
* 1018 seconds = 1 *exasecond* = 31.7 billion years
* 1021 seconds = 1 *zettasecond* = 31.7 trillion years
* 1024 seconds = 1 *yottasecond* = 31.7 quadrillion years
* 1027 seconds = 1 *ronnasecond* = 31.7 quintillion years
* 1030 seconds = 1 *quettasecond* = 31.7 sextillion years

## Teraseconds 
Here are some examples of events that take this long:
* 75,000 years — time since the ancestors of the Indigenous Australians reached Australia
* 76,000 years — half-life of nickel-59
* 154,000 years — half-life of neptunium-236
* 159,200 years — half-life of uranium-233
* 200,000 years — age of *Homo sapiens*
* 211,100 years — half-life of technetium-99
* 250,000 years — age of *Homo neanderthalensis*
* 301,000 years — half-life of chlorine-36
* 340,000 years -- half-life of curium-248
* 379,000 years -- time after the Big Bang until cosmic microwave background radiation began
* ~700,000 years -- time since the earth's magnetic field last changed
* 1,000,000 years -- the lifespan of a blue supergiant star
* 1,530,000 years -- half-life of zirconium-93
* 2,600,000 years -- amount of time the Paleolithic era lasted
* 2,600,000 years -- half-life of technetium-97
* 3.74 million years -- half-life of manganese-53
* 4 million years -- time since the last ice age
* 4.2 million years -- half-life of technetium-98 
* 6.5 million years  -- half-life of palladium-107
* 15.6 million years -- half-life of curium-247
* 20 million years -- time since the first forms of grass appeared
* 23.42 million years -- half-life of uranium-236
* 26 million years -- time since the first elephants were born 

## Petaseconds 
* 34 million years -- time since the evolution of the cat
* 34.7 million years -- half-life of niobium-92
* 49 million years -- time since the whales returned to the water
* 60 million years -- time since the evolution of the first primates.
* 135 million years -- time since end of Jurassic and beginning of Cretaceous period
* 250 million years -- Galactic year - an orbit around the center of the Milky way of our Sun and the Solar system
* 251.4 million years -- time since the Permian–Triassic extinction event
* 280 million years -- time since end of Carboniferous and beginning of Permian Period.
* 390 million years - first fishapods
* 575 million years -  age of the oldest animal fossils
* 580 million years - time since the end of a possible Snowball Earth ice age
* 703.8 million years - half-life of uranium-235
* 750 million years - time since the beginning of a possible ice age
* 1277 million years - half-life of potassium-40
* 1.8-2.1 billion years - age of the earliest eukaryotes
* 2.3 billion years - time since the first known ice age
* 3.5 to 3.8 billion years  -  age of oldest records of life: stromatolites and  cyanobacteria 
* 4.468 billion years  -  half-life of uranium-238
* 4.5 billion years  -  age of the Earth
* 13.7 ± 0.2 billion years (4e17 seconds)  -  age of the universe according to the Big Bang theory
* 20 billion years  -  time until the end of the universe in the Big Rip scenario

## Exaseconds 
* 100 billion (1011) years -- If the universe is closed, the lifetime of the universe
* Some radioisotopes have very long half-lives:
** (1.4 ± 0.4) × 1017 years – vanadium-50
** (1.9 ± 0.2) × 1019 years – bismuth-209
** (3.1 ± 0.4) × 1019 years – cadmium-116
** (2.2 ± 0.3) × 1024 years – tellurium-128