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Floating festival: the world's largest gathering of hot-air balloons takes off.

Each fall, hundreds of hot-air balloons float over Albuquerque, New Mexico. Some of the balloons are round. Others come in wacky shapes, like a pig, a sun, or a football. The spectacle kicks off the annual Albuquerque International Balloon Fiesta. It's the world's biggest hot-air balloon festival.

Hot-air balloons can soar 910 meters (3,000 feet) above the ground. That's twice the height of the Empire State Building in New York City! Flying that high can be scary at first, says Peter Cuneo. He's a balloon pilot and vice president of the Albuquerque ballooning association.

"When I took my first ride, I was anxious," says Cuneo. But understanding the science behind how hot-air balloons work gave him the confidence to take to the skies.

Liftoff!

Attached to the top of each balloon's basket is a gas burner. It heats the air inside the balloon. As the air gets warmer, "its molecules move faster and farther away from each other," says Cuneo. That causes the air's density--the amount of air filling the space inside the balloon--to decrease.

The hotter, less dense air in the balloon is lighter than the cooler, denser air outside. Buoyancy, a force that lifts an object less dense than its surroundings, causes the balloon to rise.

Takeoff is very gentle, says Cuneo. "Most people don't even know they've left the ground."

Riding the Wind

Hot-air balloons don't have steering wheels. Pilots must catch a breeze that will blow them in the direction they want to go. They move up or down to find different wind currents. Pilots heat the air in their balloons to go higher. They release some of the hot air to go lower.

At the Fiesta, pilots put their flying abilities to the test by competing to win prizes. They fly over a big contest field and try to grab keys to a new car or envelopes of money from atop 9 m (30 ft) poles. They also score points by dropping beanbags onto targets on the ground below. Controlling an eight-story balloon isn't easy. Science know-how--and a little luck--can make all the difference.

Balloon Basics

GOING UP: A hot-air balloon rises because the hot air inside is less dense than the cooler air outside.

BURNER: A gas burner shoots a flame up to 9 meters (30 feet) high into the balloon. It heats the air inside.

BASKET: The basket holds the pilot, passengers, and gas tanks to power the burner. It's attached to the balloon by steel cables.

AIR VALVE: Pulling a cord opens a valve at the top of the balloon. As hot air escapes, the balloon sinks.

ENVELOPE: The balloon's shell is made of panels of tough nylon fabric sewn together.

INSTRUMENTS: Onboard devices measure how high and fast the balloon rises.

FLOATING FESTIVAL

Lexile Level 850; Guided Reading Level R

OBJECTIVE

Understand the science behind hot-air balloons.

SETUP

Obtain a balloon, a glass bottle with a narrow neck, water, a large pot or bowl (heat resistant), and a coffeemaker. Warning: This activity involves hot water. Make sure students stand back and don't touch anything while observing.

BEFORE READING

1. Place the mouth of the balloon over the bottle's neck. Place the bottle into the pot/bowl. Ask: What is inside the bottle? (air)

2. Heat a full pot of water in the coffeemaker. Pour the hot water into the pot/bowl. Ask:

* What happened to the balloon? (It inflated.)

* Explain how the balloon inflated. (The hot water heated the air inside the bottle. That caused the air molecules to move faster and farther away from each other: As the hot air expanded, it filled the balloon.)

* What could we do to make the balloon deflate? (Add ice to the water in the pot/bowl; remove the bottle from the water and allow it to cool.)

AFTER READING

* Once in the air, how does a pilot move the hot-air balloon up and down? (The pilot adds heat to the balloon to go up and releases hot air to go down.)

* How does a pilot navigate the balloon? (The pilot moves the balloon up or down to catch different wind currents blowing in the direction he or she wants to go.)

RESOURCE

For more information on the Albuquerque International Balloon Fiesta, visit: www.balloonfiesta.com

NGSS CONNECTION

Go to www.scholastic.com/superscience to download the skills sheet "States of Matter." Students draw models of the particles in a solid, liquid, and gas.

Next Generation Science Standard Practices: Developing and Using Models
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Title Annotation:physical science
Author:Barone, Jennifer
Publication:SuperScience
Geographic Code:1USA
Date:Sep 1, 2013
Words:750
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