The Universe is incredibly huge! It’s so big that it’s hard for us to even imagine its size. But just because it’s hard to understand doesn’t mean it’s not important. The Universe is our home, and it’s fun to explore it!
Let’s start by figuring out where we live in the Universe. You can think of it like a cosmic address. For example, my cosmic address is the Crash Course Kids studio, Toronto, Canada, North America, Earth, the Solar System, the Milky Way Galaxy, the observable Universe, and finally, the Universe. Knowing our cosmic address helps us understand where things like stars, planets, and galaxies are in the sky.
Space is so vast that scientists had to create a new way to measure distances. Instead of using miles or kilometers, they use something called a light-year. A light-year is the distance light travels in one year. Light is super fast, moving at 300,000 kilometers per second! In one second, it can circle the Earth seven times. So, a light-year is a really long distance.
Here’s the big question: How big is the Universe? Well, nobody really knows! We can only see a part of it, called the observable Universe. Some things are so far away that their light hasn’t reached us yet. Beyond that, we have no idea what’s out there!
To understand the size of the Universe, let’s imagine it on a smaller scale. If the Sun were the size of a classroom, the Earth would be tiny, like a grain of salt. Our whole solar system would be just a grain of salt if the Milky Way Galaxy were the size of a room. And if the observable Universe were a room, the Milky Way would be too small to see!
The closest star to Earth is the Sun, but the second closest is Proxima Centauri, which is 4.24 light-years away. It takes light from Proxima Centauri four years to reach us. If we wanted to visit it, even in the fastest spaceship humans have built, it would take 19,000 years!
The observable Universe is 93 billion light-years across. Even using light-years, it’s still mind-bogglingly big. But even though we’re tiny in this enormous Universe, we know where we are, and that’s pretty amazing!
So, space is really big, and it’s our home. Even if we’re just small specks in a vast galaxy, we’re here, and that’s something to celebrate!
Create Your Cosmic Address: Draw a picture of your own cosmic address! Start with your home and then zoom out to include your city, country, planet, solar system, galaxy, and finally the Universe. Use different colors for each level and label them. This will help you visualize where you are in the vast Universe!
Light-Year Exploration: Try to understand how far a light-year is by using a flashlight. In a dark room, turn on the flashlight and see how quickly the light reaches the wall. Imagine that light traveling for a whole year! Discuss with your friends or family how far you think light can travel in one year and what that means for distances in space.
Starry Night Observation: On a clear night, go outside with an adult and look at the stars. Try to find the brightest star you can see. Remember, some of the stars you see might be many light-years away! Think about how long the light from those stars has traveled to reach your eyes. Share your thoughts on how this makes you feel about the size of the Universe.
