How Do Giant Parade Balloons Float? Science!

Before serving the turkey or diving straight into pumpkin pie, many families gather around their television every fourth Thursday of November to watch the streets of New York City come to life with singing, dancing and, of course, an array of giant, floating balloons at the Macy’s Thanksgiving Day Parade! Your creative thinker may have wondered aloud already: “What makes those balloons float?”

While your child might not realize that physics concepts are on display at the parade, pay attention to their “whys” and “hows” as they try to make sense of the world around them. These curious questions are perfect opportunities to encourage exploration and naturally work STEM (science, technology, engineering and mathematics) learning into your child’s everyday life.

The History of Macy’s Thanksgiving Day Parade

This famous event first began in 1924 as a Christmas parade organized by employees of an impressively large retail store in New York City. The earliest parades ended with the unveiling of the store’s beautifully decorated Christmas windows.

In 1927, it transitioned to the Thanksgiving Day Parade we know and love today. This same year, one of its most prominent features debuted and quickly became a staple of the parade moving forward — massive balloons! NBC has broadcast the parade live since 1948, allowing generations of families across the country to tune in and see the famous balloons in action.

The Science of Giant Balloons

So, how does a giant, often building-sized balloon float? You might be surprised at the similarities to the smaller-scale balloons we use to decorate birthday parties. Both require the same gas to get off the ground — helium!

For a balloon to float, its components, including the helium it’s filled with, must weigh less than the air beneath it. This creates a difference in forces (including gravity, tension and buoyancy) and pressure as the balloon displaces the air around it, forcing the air to push the balloon up.

Each enormous parade balloon is carefully designed and tested to make sure it will float properly. A balloon typically begins with a sketch, then both digital and physical 3D models are created and used to test wind flow and other variables. Next, pieces of polyurethane are heat-sealed together to form the balloon. Each one has inflation points, where it will be filled with helium. Once filled, the balloon is tested so it’s sure to look and work just right as it floats along the parade route.

Weather also plays an important role in the festivities at each year’s parade. Wind must be closely monitored the day of the event to ensure it is not too strong to safely handle the giant balloons. Additionally, heat causes the gas within the balloons to expand. Without accounting for a slight swell when filling up the balloons, we would be in for a not-so-sweet surprise as the day warms up!

To keep each larger-than-life balloon from flying away, a group of handlers, both on foot and in cars, are equipped with ropes connected to the balloons to safely steer them through the streets. You’ve seen a similar display if your child has ever used a string to anchor and control a balloon, keeping it from flying to the ceiling or bumping into people as they walk.

Next time your family watches the Thanksgiving Day Parade, we encourage you to ask your child about their favorite parts of the celebration. Then, wow them with some scientific facts on the magnificent balloon displays of beloved characters. Together, you and your child can take small steps each day to expand their STEM knowledge, because there’s always so much more to discover!

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Keep an eye on our blog for more ways your family can explore STEM concepts together.