peta- [PE tuh] +

(Greek: derived from penta-, "five"; a decimal prefix used in the international metric system for measurements)

Used in the metric [decimal] system as one quadrillion [U.S.] or thousand billionfold [U.K.], 1015 [1 000 000 000 000 000] The metric symbol for peta- is P.

petabecquerel (PBq)
A unit of radioactivity equal to 1015 atomic disintegrations per second or 27 027.03 curies (units of radioactivity).
petabyte (Pb)
1. A unit of computer memory or data storage capacity equal to 1 024 terabytes.
2. One quadrillion bytes. A typewritten page is said to have about 2 000 bytes of data per side; therefore, a megabyte represents a 500 text page per side and a petabyte would be 500 billion pages.
A measure of a computer's processing speed and can be expressed as a thousand trillion floating point operations per second.

A flop refers to the floating-point operations per second. It is considered to be a method of encoding "real" numbers within the limits of finite precision available on computers.

The IBM machine, codenamed Roadrunner, has been shown to run at "petaflop speeds", and it will be used for research into astronomy, genomics, and climate change. It has been modified to handle a greater bandwidth of data and to carry out more specialized calculations.

petaflops (Pf)
This represents 1 000 (1015) teraflops (floating point operations) per second.

One trillion calculations, or floating point operations, per second.

The first supercomputer capable of crunching through a thousand trillion mathematical operations every second has been announced by IBM. This is roughly equivalent to the combined processing power of a 2.4-kilometer-high pile of laptop computers.

Blue Gene/P will be capable of a peak performance of 3000 trillion calculations, or floating point operations, per second (three petaflops); but its sustained performance is expected to level out at around one petaflop.

—Excerpts from "IBM creates world's most powerful computer"
by Will Knight, news service, June 27, 2007.
petagram, Pg
A metric unit of mass equal to 1015 grams or one gigatonne (one billion metric tons).

This unit is used in atmospheric science and other scientific contexts where large masses are considered.

petahertz (Ph)
One quadrillion hertz (1015).
petajoule (Pj)
The largest producer of energy: in 2001, the USA produced 75,295 petajoules of commercial energy, inclueding solid, liquid, and gaseous fuels; as well as, primary electricity.

A petajoule is 1,000,000,000,000,000 joules.

Guinness World Records 2005; Special 50th Anniversary Edition
(1955-2005, "The environment"),Guinness World Records, Ltd., 2004; page 84.
petameter (Pm)
1. One light-year (distance light travels in one year) is equal to 9.5 Pm (petameters).
2. Dinosaurs are estimated to have vanished two Ps (petaseconds) ago.
— Source: Chemistry and Molecular Biology Resources,
UC Extension, Berkeley/San Francisco
petawatt laser
When the petawatt laser is turned on, it has the power output of more than 2,000 times the output of all power plants in the United States.

A petawatt is one quadrillion watts. The laser is brighter than sunlight on the surface of the sun, but it only lasts for an instant, a 10th of a trillionth of a second (0.0000000000001 second).

The Texas Petawatt is the only operating petawatt laser in the United States; located at The University of Texas, in Austin. On Monday, March 31, 2008, the Texas Petawatt laser reached greater than one petawatt of laser power, making it the highest powered laser in the world.

—As seen in the "" site;
source: University of Texas; Austin, Texas; April 8, 2008.

Related "metric" families: yotta; zetta; exa; tera; giga; mega; kilo; hecto; deka; deci; centi; milli; micro; nano; pico; femto; atto; zepto; yocto.