Imagine you’re an old sea captain sailing your ship through dark waters. It’s late at night and clouds block all the light from the moon. You know you’re near land, but you’re not sure how close you are.

You don’t want to run aground and sink your ship. So you keep a close eye out for signs of danger. Then, over there, you see something. It’s just a blip of light. But there it goes again! What is it? It’s the beacon of a lighthouse helping to guide you safely home.

Lighthouses are towers, buildings or other usually tall structures that shine bright lights to help guide ships at sea. With the help of lighthouses, ships can safely avoid dangerous coastlines and reefs. Lighthouses also help mark the entrances of harbors and bays.

The first lighthouses were lit by open fires or candles. Eventually, other substances, including whale oil, lard oil and kerosene, were used to produce light. Once electric lights were invented, they became the primary light source.

The light source in a lighthouse is called the lamp. To reach ships out at sea, the light source must be concentrated and projected. This is accomplished by using a series of lenses that are often called optics.

The Fresnel lens, invented in 1822 by French physicist Augustin-Jean Fresnel, allowed the light from the lamp in a lighthouse to be projected great distances. Rotating mechanisms were also introduced to allow the light to be projected in a circular fashion all around the lighthouse, thereby increasing visibility.

To be effective, the light from a lighthouse must be high enough to be seen by ships long before they get too close to danger. This led many lighthouses to be designed by architects and engineers as tall cylinders. The cylindrical shape reduces the effect of strong winds. Of course, if a cliff is near the seashore, a lighthouse doesn’t have to be nearly as tall.

Sometimes, lighthouses have to be built in the water. Dangerous reefs, for example, can exist far off coastlines. In these areas, lighthouses built off-shore can still help ships avoid these dangers.

So where is the tallest lighthouse? That might seem like an easy question, but there’s actually some controversy about what should be considered a lighthouse. For example, some tall structures incorporate lights that can be used as beacons for navigation.

Jeddah Light in Saudi Arabia stands 436 feet tall and has a credible claim as the tallest lighthouse in the world. Other challengers include the 348-foot-tall Yokohama Marine Tower in Japan and the 352-foot-tall Perry Memorial Monument in Ohio. Neither the Yokohama Marine Tower nor the Perry Memorial Monument, however, were built for the specific purpose of being a traditional lighthouse, so some dispute their claims.

The tallest traditional lighthouse is widely considered to be 271-foot-tall Île Vierge Lighthouse in France. Built in 1902, it’s made of granite and is the tallest stone lighthouse in the world today.

Lighthouses are still used today, but they’re not as necessary as they once were. Thanks to advances in navigational technology, many lighthouses have been shut down due to the expense of maintaining them. In fact, the last manned lighthouse built in the United States was the Charleston Lighthouse, which was built in 1962.

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    • Good guess, Savia! However, today’s Wonder mentions a lighthouse in France that is known as the tallest! Perhaps you can read today’s Wonder to learn more! :)

    • So cool, Blakeleigh, we’re glad you have joined us today to Wonder about lighthouses! They’re great at guiding! Have a great day, Blakeleigh! :)

  1. That is a really cool wonder! I read a novel called Nick of Time and the main character is a lighthouse keeper’s son. It was interesting to learn where the tallest lighthouse is. Thank you for today’s wonder! :) ;)

    • Thanks for WONDERing with us today, Berkleigh! What a great connection to the book you read– it sounds great! We are so glad you visited us! :)

  2. Hi there. I’m in Mrs. Hess’s class and this video is wonderful how lighthouse light up the world! I want to see wonderful videos and also funny videos, too! Who invented the lighthouse?

    I wonder tomorrow’s WONDER is about nails, hair, toys, designs, makeups… and have a wonderful weekends! See you later!

    • Hi there, Kathy! We’re so happy that you’re WONDERing with us today! Thanks for telling us how much you enjoyed today’s Wonder– it really made us light up, too! A French physicist invented the lighthouse, but other researchers and historians say that ancient Egyptians were the first to build lighthouses! We bet you can Wonder some more at the library or on the Internet! Thanks for visiting us today! :)

  3. Hello, my name is Briahna and I did not expect today’s wonder to be about lighthouses. I have never seen a lighthouse in person, but hope to see one soon! I am truly surprised everyday by your wonders.

    • Well thanks so much, Briahna! We are so glad that you enjoy WONDERing with us– it’s so much fun! :) We hope you can see a lighthouse in person, too! In the meantime, have a great day! :)

    • Hi there, Laila! We are so glad you shared your comment with us! We bet you will learn where the tallest lighthouse stands today if you read the Wonder! Good luck! :)

  4. Cape Hatteras, which is in NC, is the tallest lighthouse in America … It is 200 feet tall which makes it the 23rd tallest traditional lighthouse in the world.

    • WOW, how cool, Melissa! It’s amazing that Cape Hatteras is the tallest lighthouse in the U.S., but it’s #23 in the world! We bet it’s still a great guide for ships sailing in the night! Thanks for making our Wonder even better! :)

  5. I still cannot believe that some lighthouses help guide ships, but than what if type boat smash each other then that would be a disaster. That must might have happen to the titanic (just kidding).

    • Hi there, Joseph! We’re so glad you have been WONDERing about lighthouses with us, especially since they act as a guide to ships. Just like there are rules to driving on the road, there are also rules of the sea. Unfortunately, accidents still happen, but they usually involve collisions with other objects (like icebergs, for example). Technology today helps a great deal, and captains use technology to make sure their boat and crew are safe and sound. You can Wonder about technology here, too: Wonder #710– How Does Technology Change Lives? http://wonderopolis.org/wonder/how-does-technology-change-lives/ :-)

    • That’s a great guess, Wonder Friend Mitko! Thanks for sharing your comment! We Wonder if you checked out our Wonder to find out where the tallest lighthouse is (at least for the time being!) :)

  6. I really don´t know where´s the tallest lighthouse made by man, but I know, nowadays, the tallest natural lighthouse is in Mazatlan, Mexico

    • Thanks for sharing that with us, Monica! We Wonder if you’ve ever seen it in person? Thanks for WONDERing with us today! Talk to you again soon! :)

  7. You have some incorrect information in your last paragraph. The last lighthouse built in the US was not the Charleston Lighthouse, but rather Sullivan’s Island Lighthouse in Charleston. You can see it here: http://www.us-lighthouses.com/displaypage.php?LightID=178.

    You actually show a picture of the Morris Island Lighthouse, built in 1876. See here: http://www.us-lighthouses.com/displaypage.php?LightID=177.

    And furthermore, there is still a manned lighthouse in the US. The Boston Lighthouse on Little Brewster Island, was never automated. It is still manned by the U.S. Coast Guard.

    Hope this helps.

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Have you ever wondered…

  • Where is the tallest lighthouse?
  • Are lighthouses still used today?
  • What makes the lights in lighthouses so bright?

Wonder Gallery

LighthouseVimeo Video

Try It Out

Want to see and learn more about lighthouses? Call out to a friend or family member to help you explore one or more of the following fun activities:

  • Jump online to visit U.S. Lighthouses. Visitors to the site have voted on their favorite lighthouses from around the country. Check out some of the top favorites at the links below:
  • Feeling crafty? With a few simple supplies, you can build your own model lighthouse. Simply follow the online instructions and you’ll be engineering your own unique model lighthouse in no time. Things you’ll need include: a large paper plate, markers or paint, a ruler, scissors, an empty toilet paper roll, construction paper, tape, a Styrofoam cup, glue, a wooden bead and a wooden toothpick.
  • Want to explore the science of light up close and personal? How about building your own flashlight? Follow the online instructions to give you an idea of what will be involved. Be warned, though, this will take a lot of experimentation, thought and creativity on your part. You’ll need several cheap flashlights that you can take apart to examine how they work. You might want to use them for parts, too, as you build your own creation. Be sure to ask an adult for help and permission to disassemble some old flashlights!

Still Wondering

Have you ever wondered how the lights in lighthouses are so bright? Check out Smithsonian’s History Explorer to learn more about Lenses and Lighthouses.

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