Terasecond and longer facts for kids

A terasecond (symbol: Ts) is a super long amount of time! It's equal to one trillion seconds. To give you an idea, that's about 31,700 years. You can also write it as 10¹² seconds.

Imagine time spans even bigger than a terasecond:

• 10¹⁵ seconds = 1 petasecond = about 31.7 million years
• 10¹⁸ seconds = 1 exasecond = about 31.7 billion years
• 10²¹ seconds = 1 zettasecond = about 31.7 trillion years
• 10²⁴ seconds = 1 yottasecond = about 31.7 quadrillion years

What is a Terasecond?

A terasecond is a huge unit of time. It helps us talk about events that happened a very, very long time ago or things that last for an incredibly long time.

Events Measured in Teraseconds

Here are some cool examples of things that take a terasecond or more:

• 75,000 years: This is how long ago the ancestors of the Indigenous Australians first arrived in Australia.
• 200,000 years: This is roughly how old our own species, Homo sapiens, is!
• 250,000 years: This is about how long ago the Homo neanderthalensis species appeared.
• 379,000 years: This is the time after the Big Bang when the universe cooled enough for light to travel freely, creating the cosmic microwave background radiation we can still detect today.
• About 700,000 years: This is how long ago the earth's magnetic field last flipped its north and south poles.
• 1,000,000 years (1 million years): This is how long a giant blue supergiant star might live.
• 2,600,000 years: This is how long the Paleolithic era, also known as the Old Stone Age, lasted.
• 4 million years: This is roughly how long ago the last major ice age ended.
• 20 million years: This is when the first types of grass started growing on Earth.
• 26 million years: This is when the first elephants appeared on Earth.

What is a Petasecond?

A petasecond is even longer than a terasecond. It's used for events that span tens of millions to billions of years.

Events Measured in Petaseconds

Let's look at some events that are measured in petaseconds:

• 34 million years: This is roughly how long ago cats started to evolve.
• 49 million years: This is when whales began to return to living in the water.
• 60 million years: This is about how long ago the first primates (the group that includes monkeys, apes, and humans) evolved.
• 135 million years: This marks the end of the Jurassic period and the start of the Cretaceous period. Dinosaurs were still around!
• 250 million years: This is a Galactic year! It's how long it takes our Sun and the Solar system to orbit once around the center of the Milky Way galaxy.
• 251.4 million years: This is when the Permian mass extinction happened, one of the biggest extinction events in Earth's history.
• 390 million years: This is when the first fishapods, early creatures that could live both in water and on land, appeared.
• 575 million years: This is the age of the oldest known animal fossils.
• 1.8 to 2.1 billion years: This is the age of the earliest eukaryotes, which are cells with a nucleus, like the cells in plants, animals, and fungi.
• 2.3 billion years: This is when the first known ice age happened, where Earth might have been almost completely covered in ice.
• 3.5 to 3.8 billion years: These are the ages of the oldest signs of life on Earth, found in stromatolites and cyanobacteria fossils.
• 4.5 billion years: This is the approximate age of the Earth itself!
• 13.7 ± 0.2 billion years: This is the estimated age of the universe according to the Big Bang theory.

What is an Exasecond?

An exasecond is an even more enormous unit of time, used for truly mind-boggling durations.

Events Measured in Exaseconds

• 100 billion (10¹¹) years: If the universe is closed, this could be the total lifetime of the universe.

Some radioisotopes (unstable atoms) have incredibly long half-lives that are measured in exaseconds. A half-life is the time it takes for half of the atoms in a sample to decay. These are some of the longest-lasting substances known!