Countdown facts for kids

A countdown for the 2015 FIFA Women's World Cup in Canada.

A countdown is when you count backward from a certain number to zero. It shows how much time is left before something important happens. Think of it like counting down to your birthday party!

Countdowns are used for many exciting events. For example, NASA uses them before a rocket launch. They often say "T-minus" for rocket launches. "T" stands for "Time" or "Test." They also use "E-minus" for events with spacecraft already in space, where "E" means "Encounter" with a comet or another space object.

You might also see countdowns for the start of a race, the beginning of the New Year, or any other event people are really looking forward to.

Rocket Launch Countdowns

A countdown clock at NASA's Kennedy Space Center showing 11 hours left before the launch of Space Shuttle Endeavour.

A countdown for a rocket launch is a very detailed plan. It includes many steps that must happen before the rocket's engines can start. These countdowns can begin many hours, sometimes even days, before the launch time.

During a rocket countdown, many important things happen:

• Space experts bring the rocket to the launch pad.
• They load the rocket with its cargo and fuel.
• Computers at the launch center check all the rocket's systems.
• Launch teams watch the weather closely. They wait for the perfect "launch window," which is a specific time when conditions are right.
• Security teams make sure no unauthorized people enter the launch area.

Countdowns in Film

Have you ever seen an old movie start with numbers counting down on the screen? This is a countdown sequence printed on the film itself. It helps movie projectionists get the film ready and start it at the right moment. In movies, these countdowns are measured in feet of film, not in seconds.

New Year's Eve

One of the most famous countdowns happens every year on New Year's Eve. People around the world count down the last few seconds of the old year. When the countdown reaches zero, everyone celebrates the start of the new year!

Images for kids

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  Seven seconds after the launch of STS-121, the countdown clock at LC-39 is seen counting up, not down.

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  A newer (1959) SMPTE countdown on the head leader of a film reel.

See also

In Spanish: Cuenta atrás para niños