Orders of magnitude (time) facts for kids
Have you ever thought about how long a second really is? Or how short a millisecond is? An order of magnitude of time is a way to organize time into different scales, from incredibly tiny fractions of a second to billions of years. It's like using a zoom lens to look at time, from the blink of an eye to the age of the universe.
We usually measure time in base units like seconds or years. We then add prefixes to show if we're talking about a much smaller or much larger amount of time. For example, "milli-" in "millisecond" means one-thousandth. We don't usually use prefixes for years, so we say "a million years" instead of "a megayear."
The smallest slice of time that scientists can imagine is called the Planck time. The largest amount of time we know of is the age of the universe, which is about 13.8 billion years old. That's the time that has passed since the Big Bang.
Contents
Tiny Slices of Time
Let's look at units of time that are shorter than one second. These moments are so fast that we can't experience them, but they are very important in science and technology.
| Unit | Fraction of a Second | What It's Like |
|---|---|---|
| millisecond (ms) | One-thousandth (1/1,000) | A camera flash lasts for about 1 millisecond. A bee can flap its wings once in about 5 milliseconds. |
| microsecond (μs) | One-millionth (1/1,000,000) | A modern computer needs a few microseconds to do a simple calculation. |
| nanosecond (ns) | One-billionth (1/1,000,000,000) | In one nanosecond, light travels about 30 cm (1 foot). A fast computer processor takes about 1 nanosecond to do one step. |
| femtosecond (fs) | One-quadrillionth | This is the timescale on which molecules vibrate and chemical reactions happen. |
| attosecond (as) | One-quintillionth | This is about the time it takes for an electron to travel around the nucleus of an atom. |
The Smallest Possible Moment
Scientists believe the Planck time is the smallest possible unit of time that makes sense in physics. It is an incredibly tiny fraction of a second, so short that it's almost impossible to imagine. It is the time it takes for light to travel the smallest possible distance.
From Seconds to Centuries
Now let's look at larger amounts of time, starting from one second and going up. These are units we are more familiar with in our daily lives.
| Unit | How Many Seconds? | In Common Time | Examples |
|---|---|---|---|
| decasecond (das) | 10 seconds | 10 seconds | The time for a quick countdown before a race. |
| hectosecond (hs) | 100 seconds | 1 minute, 40 seconds | The time it might take to run a short race. |
| kilosecond (ks) | 1,000 seconds | About 17 minutes | A short TV show might be about 1.8 kiloseconds long. One hour is 3.6 kiloseconds. |
| megasecond (Ms) | 1,000,000 seconds | About 11.5 days | A month has about 2.5 megaseconds. A year has about 31.5 megaseconds. |
| gigasecond (Gs) | 1,000,000,000 seconds | Nearly 32 years | A person who is 80 years old has lived for about 2.5 gigaseconds. A century (100 years) is about 3.16 gigaseconds. |
Cosmic and Geological Time
To talk about the history of our planet and the universe, scientists need even bigger units of time. These time scales are so long they are hard to comprehend.
- Mega-annum (Ma)
This means one million years. It is often used in geology and paleontology. 2.5 Ma: The approximate time since the earliest human ancestors, like Australopithecus, appeared in Africa. 66 Ma: The time since the Cretaceous-Paleogene extinction event, when the dinosaurs (except for the ancestors of birds) went extinct.
- Giga-annum (Ga)
This means one billion years. It is used for talking about the history of planets and the universe. 1 Ga: The Sun will become so hot in about 1 billion years that life on Earth will no longer be possible. 4.5 Ga: The approximate age of the Earth. 13.8 Ga: The approximate age of the Universe. This is the time since the universe began with the Big Bang.
See also
- Geologic time scale
- International System of Units
- Orders of magnitude (frequency)
- Planck units
- Scale (analytical tool)
- Temporal resolution
- Timeline of the far future
- Year
