How Do Fireworks Actually Work?

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iStock

by Sarah Dobbs

Each year, as the Fourth of July approaches, the sound of explosions starts to become a normal part of the evening. Fireworks have existed in one form or another for around 1000 years, and they show no signs of going away anytime soon. But how do they work? Most of us just know to light the fuse and stand back. Let’s take a closer look …

ROCKETS

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Rocket-type fireworks can produce all kinds of different effects when they go off, but the basic structure of an aerial firework stays more or less the same. Each rocket is made up of the following parts: a mortar, fuses, propellant powder, a shell, a bursting charge, and a collection of "stars." The mortar is the outer container, and the fuse is, of course, the piece that you light. When the fuse burns down, the propellant ignites and shoots the firework into the air.

When it’s airborne, a second explosion is triggered inside the shell by a time delay fuse. The bursting charges set off the stars—small, explosive pellets made of fuel and metallic compounds that create the lights in the fireworks display. Different metals create different colors when they ignite: barium goes green, calcium salts go orange, magnesium goes white, copper is blue, lithium turns red, and sodium becomes gold. And the arrangement of the stars will determine the shape of the explosion—so if they’re packed in a heart shape, they should reproduce that heart shape in the sky.

Other effects can also be built in by adding various ingredients; different kinds of fuel can create sound effects, for example, like the whistling or screaming noises some rockets make as they shoot into the sky. Stars can be made up of layers of different metallic compounds, to create multicolored explosions. And in some more complex fireworks, there may be several stages of explosions; in that case, there are generally multiple fuses inside the shell, and as each burns down, a different explosive goes off.

FOUNTAINS

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Of course, not all fireworks are of the shoot-into-the-air-and-go-bang variety. Fountains don’t take off, and generally don’t go bang, either; instead, they stay where they’re placed and give off a cascade of sparks—like a fountain, but with pyrotechnics instead of water.

Usually conical in shape, fountains consist of a paper or plastic tube, with clay plugs at either end. Inside the tube are a couple of different kinds of fuel, plus the metal compounds that create the sparks. When the fuse is lit, the fuel ignites, and sparks are forced out of an aperture in the top of the fountain.

Again, different metals create different colors and effects. Multi-stage effects can be created by bundling multiple tubes together, so that as one finishes another starts, adding different colors or sound effects to the display.

CATHERINE WHEELS

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Catherine wheels are another common type of firework, and again the same kinds of ingredients are used to create a slightly different effect. Named for the unfortunate Saint Catherine, these fireworks are generally fixed to a pole or a mount, so that they can spin as they burn, creating a spiral of sparks.

Bigger Catherine wheels tend to have a plastic disk at their center, with “gerbs” attached around the edge. The gerbs are similar to fountains, in that they’re tubes filled with the mixture of ingredients that create the effects; when lit, the thrust from the explosives makes the wheel turn as they burn. And again, the effect can be made more elaborate with multi-stage effects and different colors; each gerb might be different, so that the wheel changes as each one ignites in turn.

Smaller Catherine wheels might, instead, be made up of a single long, thin tube coiled into shape around a smaller central disk. Again, the thrust of ignition makes the wheel spin.

SPARKLERS

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The only firework you should ever hold in your hand once it’s lit is a sparkler—a Fourth of July staple. Unlike most other fireworks, they don’t explode with a bang, but gently fizzle for around a minute, as a ball of sparks makes its way down a metal wire. And they’re pretty simple: basically, the metal wire is dipped into a pyrotechnic compound that’s made up of a metallic fuel, an oxidizer, and a binding material.

The metallic fuel is what creates the sparks; it’s usually aluminum or magnesium, which creates white sparks, but some sparklers may use iron or ferrotitanium for gold sparks instead. The oxidizer, which provides the oxygen to keep the spark going, is generally potassium nitrate. And then a binding material, a kind of flammable starch, keeps the mixture together, and burns away once the sparkler is lit.

Hopefully, none of that has taken away any of the magic of a good fireworks display. If nothing else, you’ll be able to impress your friends by quietly musing “oooh, barium” next time you see a green firework.

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Amazon's Under-the-Radar Coupon Page Features Deals on Home Goods, Electronics, and Groceries

Stock Catalog, Flickr // CC BY 2.0
Stock Catalog, Flickr // CC BY 2.0

This article contains affiliate links to products selected by our editors. Mental Floss may receive a commission for purchases made through these links.

Now that Prime Day is over, and with Black Friday and Cyber Monday still a few weeks away, online deals may seem harder to come by. And while it can be a hassle to scour the internet for promo codes, buy-one-get-one deals, and flash sales, Amazon actually has an extensive coupon page you might not know about that features deals to look through every day.

As pointed out by People, the coupon page breaks deals down by categories, like electronics, home & kitchen, and groceries (the coupons even work with SNAP benefits). Since most of the deals revolve around the essentials, it's easy to stock up on items like Cottonelle toilet paper, Tide Pods, Cascade dishwasher detergent, and a 50 pack of surgical masks whenever you're running low.

But the low prices don't just stop at necessities. If you’re looking for the best deal on headphones, all you have to do is go to the electronics coupon page and it will bring up a deal on these COWIN E7 PRO noise-canceling headphones, which are now $80, thanks to a $10 coupon you could have missed.

Alternatively, if you are looking for deals on specific brands, you can search for their coupons from the page. So if you've had your eye on the Homall S-Racer gaming chair, you’ll find there's currently a coupon that saves you 5 percent, thanks to a simple search.

To discover all the deals you have been missing out on, head over to the Amazon Coupons page.

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Why Does the Supreme Court Have Nine Justices?

Front row, left to right: Stephen G. Breyer, Clarence Thomas, (Chief Justice) John G. Roberts, Jr., Ruth Bader Ginsburg, Samuel A. Alito. Back row: Neil M. Gorsuch, Sonia Sotomayor, Elena Kagan, Brett M. Kavanaugh.
Front row, left to right: Stephen G. Breyer, Clarence Thomas, (Chief Justice) John G. Roberts, Jr., Ruth Bader Ginsburg, Samuel A. Alito. Back row: Neil M. Gorsuch, Sonia Sotomayor, Elena Kagan, Brett M. Kavanaugh.
Fred Schilling, Collection of the Supreme Court of the United States // Public Domain

Some facets of the U.S. government—like presidential terms and post offices—were written into the original Constitution after (often lengthy) deliberations by the Founding Fathers. The number of Supreme Court justices was not one of those things.

The document did establish a Supreme Court, and it stated that the president should appoint its judges; it also mentioned that a “Chief Justice shall preside” if the president gets impeached. Since it was left up to Congress to work out the rest of the details, they passed the Judiciary Act of 1789, which outlined an entire court system and declared that the Supreme Court should comprise one chief justice and five associate justices. As History.com explains, they landed on six because the justices would have to preside over federal circuit courts, one of which was located in each state. Traveling wasn’t quick or easy in the horse-and-carriage days, so Congress wanted to minimize each justice’s jurisdiction. They split the courts into three regions, and assigned two justices to each region.

According to Maeva Marcus, director of the Institute for Constitutional History at George Washington University Law School, the even number of justices was a non-issue. “They never even thought about it, because all the judges were Federalists and they didn’t foresee great disagreement,” she told History.com. “Plus, you didn’t always have all six justices appearing at the Supreme Court for health and travel reasons.”

Over the next 80 years, the number of Supreme Court justices would fluctuate for two reasons: the addition of federal circuit courts, and presidents’ partisan motives. John Adams and his Federalist Congress reduced the number to five with the Judiciary Act of 1801, which they hoped would prevent Democratic-Republican Thomas Jefferson from getting to fill a seat after he took office that year. By the following year, Jefferson’s Congress had passed another judicial act that returned the number of justices to six, and they upped it to seven after forming another circuit court in 1807.

The nation grew significantly during the early 19th century, and Congress finally added two new circuit courts—and with them, two new Supreme Court seats—during Andrew Jackson’s presidential tenure in 1837. Republican Abraham Lincoln then briefly increased the number of justices to 10 in order to add another abolitionist vote, but Congress shrunk it to seven in 1866 to keep Andrew Johnson from filling seats with Democrats. As soon as Republican Ulysses S. Grant succeeded Johnson, Congress set the number back to nine, where it’s remained ever since.

Sketched portraits of the U.S. Supreme Court justices through 1897.Popular and Applied Graphic Art Print Filing Series, Library of Congress Prints and Photographs Division // No Known Restrictions on Publication

In 1911, Congress did away with circuit courts altogether, so the number of Supreme Court justices stopped being contingent upon their expansion (though each justice does still oversee a region to help with occasional tasks). As for presidents shifting the number to serve their own goals, it’s now looked down upon as “packing the court.” When Franklin D. Roosevelt tried to increase it to 15 in the 1930s to push his New Deal through the Supreme Court, the Senate opposed the bill by a whopping 70 to 20 votes.

In short, the depth of the Supreme Court’s bench changed a lot in America’s early years not only because the country was expanding, but also because the federal government was still testing out its system of checks and balances. And though presidents do still appoint justices based on their own political party, we’ve gotten used to the idea that the Supreme Court is, at least ideologically, supposed to be unbiased. If Congress and the president kept up the habit of adding and subtracting justices at will, it would tarnish this ideal.

“If Congress increases the size of the Supreme Court for transparently partisan political reasons, it would cement the idea the justices are little more than politicians in robes, and that the court is little more than an additional—and very powerful—arm through which partisan political power can be exercised,” Steve Vladeck, a professor at the University of Texas School of Law, wrote for NBC News. “Indeed, that Congress has not revisited the size of the court in 150 years is a powerful testament to just how ingrained the norm of nine has become—and how concerned different political constituencies have been at different times about preserving the court’s power.”

[h/t History.com]