Visualizing the Speed of Light (Fast, but Slow)

Visualizing the Speed of Light

With the flip of a switch, your room can be instantenously flooded with brightness.

In fact, there is no noticeable lag effect at all.

That’s because emitted photons travel at 186,000 miles (300,000 km) per second, meaning it takes only 1/500,000th of a second for light to reach even the furthest part of an ordinary room. And, if it could go through the wall, it would orbit the entire planet 7.5 times in just one second.

Light Speed is Fast…

In our every day experiences, we never see light as having to “take time” to do anything. It’s inconceivably fast, brightening up everything in its path in an instant — and with a few odd caveats, scientists believe light speed to be the fastest-known achievable pace in the universe.

But what if we get out of our bubble, and look at light from outside the confines of life on Earth?

Today’s animation, which comes from planetary scientist Dr. James O’Donoghue, helps visualize the speed of light in a broader context. It helps remind us of the mechanics of this incredible phenomenon, while also highlighting the vast distances between celestial bodies — even in our small and insignificant corner of the solar system.

Light Speed is Slow…

Once a photon is sent into the vast abyss, suddenly the fastest possible speed seems somewhat pedestrian.

• Moon: It takes about 1.255 seconds for light to get from Earth to the moon.
• Mars: Mars is about 150x further than the moon — about 40 million miles (54.6 million km) in the closest approach — so it takes 3 minutes to get there from Earth.
• Sun: The sun is 93 million miles (150 million km) away, meaning it takes 8 minutes to see its light.

Let that sink in for a moment: the sun could explode right now, and we wouldn’t even know about it for eight long minutes.

Going Further, Taking Longer

If it takes light a few minutes to get to the closest planets, how long does it take for light to travel further away from Earth?

• Jupiter: The largest planet is 629 million km away when it’s closest, taking light about 35 minutes.
• Saturn: The ringed planet is about as twice as far as Jupiter, taking light 71 minutes.
• Pluto: It takes about 5.5 hours for light to go from Earth to the dwarf planet.
• Alpha Centauri: The nearest star system is 4.3 light years away, or 25 trillion miles (40 trillion km).
• Visible stars: The average distance to the 300 brightest stars in the sky is about 347 light years.

If you really want to get the feeling of how “slow” light really is, watch the below video and journey from the sun to Jupiter. It’s done in real-time, so it takes about 43 minutes:

So while light obviously travels at a ludicrous speed, it really depends on your vantage point.

On Earth, light is instantaneous – but anywhere else in the universe, it’s pretty inadequate for getting anywhere far (especially in contrast to the average human lifespan).