(CNN) Whatever the James Webb Space Telescope, the Hubble Space Telescope, or other space exploration tools discover next, it will likely be located several light-years away.
But how far is a light-year — really? The circumference of our planet is 24,873.6 miles (40,030.2 kilometers) and our planet is 93 million miles (149.6 million kilometers) from the sun.
A light-year is more — it’s the distance that light travels in one year, that is 5.88 trillion miles (9.46 trillion kilometers).
Just one light year away from Earth is insanely far away. CNN spoke with the science educator and engineer Bill Nye to try to understand the magnitude of the universe and how we measure it.
This conversation has been slightly edited and shortened for clarity.
Bill Nye arrives at National Geographic’s “Cosmos: Possible Worlds” Los Angeles Premiere at Royce Hall, UCLA, on February 26, 2020.
CNN: What is a light-year?
Bill Nye: A light-year is how far a ray of light travels in one year — (over) 5.88 trillion miles. When scientists or astronomers use the shorthand “light,” we mean the speed of light in one year. If you drive 60 miles per hour for one hour, you will walk 60 miles.
Now, don’t come to me about “I can’t do algebra, I hate math. Bill Nye, you’re a bad person.” No — distance is rate (speed of light) times time (one year). It’s a long way! And, what the James Webb Space Telescope recently discovered is that we — as far as we can tell — are looking at light that came from the other side of the universe after the Big Bang.
CNN: Why does outer space have a different unit of measurement?
Nye: There is a lot of space in the universe. It’s so vast, and you have people like us trying to make sense of it. Astronomers want manageable units of measurement. Writing millions or billions and billions of miles and kilometers is very difficult! You start going to zero, then zero, then zero, then zero — just a lot of zeros, and you lose track. Then, these distances start to have less meaning. Space becomes more difficult to understand.
Like Earth years, a light-year can be divided into smaller units such as a light day, hour, minute, etc. In one light-minute, light travels 11,160,000 miles.
Because space is so vast and celestial objects are so far apart, it can take time for light from these objects to reach each other. The sun is 8.3 light-minutes away from Earth, which means if you look at the sun — please don’t — you see it as it was 8.3 minutes ago.
According to I hope in, if you were to travel from the sun to the edge of our solar system, it would take about 1.87 years at the speed of light. But to get to our nearest neighboring galaxy at the speed of light, Andromeda, it will take 2.5 million years. That doesn’t cover a fraction of the universe’s total real estate.
CNN: Is it frustrating to think about things in the universe that are so far away from us that we may never be able to study them?
Nye: It’s the coolest thing ever that there’s so much we don’t know! There is so much more to discover out there and perhaps the idea that we will never know is wrong. Maybe there is a way to find out. Maybe there’s a way to find out if we’ll ever find out or not, you know?
It’s easy to throw out big numbers with zeros, but it’s harder to understand the truth of vastness of the universe sincerely
CNN: When we’re talking about big numbers like millions and billions, especially in terms of light-years, how do we try to visualize that magnitude?
Nye: If you could stay awake, sleepless, and count once every second — one, two, three, four — to reach a million, it would take you over 11 days. That too all night. To get to a billion, that takes more than 31 years. The Earth has been around for three point and a billion years. Now, you’re talking 120 years of no naps, no milkshakes, and counting to get to a billion. So, reaching 13.7 billion, the age of the universe, is literally — and when I say literally, I mean literally — unthinkable.
CNN: Why is it important to understand the meaning of the light-year, and what does it tell us about space?
Nye: This conversation we’re having today (on Zoom) is entirely dependent on space exploration. There is no way we can have global communication without space technology. And storm systems that move across North America — we’ll never know about those without satellites and all the ground systems we’ve built to get data up and down from them.
I encourage everyone to take the time to understand what a light-year is. This is the speed of light in one year. Also understand what this means cosmically — that is, what it means for two big questions: Are we alone? And where do we come from?
