If you think that the speed of the light is the only thing that is keeping you from visiting other stars in the universe, you’re wrong my friend. The light speed is only 299,792 KM/Second and before you get paranoid by focusing on the word ‘only’, let me show you why we need to go even faster than the speed of light to even escape our own galaxy, The Milky Way.
First, let’s start with the basics so that the main thing would make absolute sense to you.
What is a light year?
Most school students get confused in the meaning of a light year. It may sound like ‘time’, but it’s actually ‘distance’. The distance traveled by the light in 1 year, is known as one light year. It is 9.5 trillion km.
What is a light month?
Simple, the distance traveled by light in one month is known as one light month. It is 792 billion km.
What is a light minute?
Distance traveled by light in one minute. It would come to about 18 million km.
And a light second?
I already told you, it is 299,792 km (distance traveled by light speed in one second).
Light takes 8 minutes to reach the surface of the earth from the Sun. This distance is more commonly known as 1 AU (Astronomical Unit) which is close 150 million km.
So why do we need to go faster than the speed of light to even think of exploring our galaxy?
Our galaxy, the milky way, is about 100,000 light years wide. meaning that the light would take 100,000 years to go from one end of the galaxy to another. So, if we were to reach from one end of the galaxy to another and the fastest we could go is the light speed (just assume it), it would take us, 100,000 years to do so. That is how big our own galaxy is. And, last I checked, no human ever lived that long.
Now that you know how long it takes to move around in this ridiculously gigantic universe, let me astonish you with some of the space facts below:
We can’t ever travel at light speed, let alone surpass it
Photons that travel at light speed, do so because they do not have mass. To travel at the speed of light, an object shouldn’t have any mass. So, we as humans can never travel at the light speed, neither can we send an object at the speed of light into space. In theory, however, a wormhole allows one to travel great distances even faster than the speed of light maybe. A wormhole is said to bend the space and being two distant points together for the object to jump to the other part of the universe without actually traveling the distance. Watch Christopher Nolan’s epic Interstellar for more details 😛
Everything you see in the night sky is in the past, you can never know the present
How do we see things? We either see an incident ray or a reflected ray of light. Without light, we can literally see nothing. So, to see any object, our eyes must receive the light coming from that object (either a reflection or an incidence). It means that if we see a distant star in the night sky, we are actually seeing the light coming from that star. But, I just established the fact that distant stars so distant that even at the speed of light, it takes several thousand and even millions of years to reach us. It simply means that by the time light from a distant star reaches us, it may already have been thousands/millions of years. If that star explodes and dies today, it will take another thousand/million years before we know it. For them, it will again be a past.
How about objects in our own solar system? Are they in the past too?
Yes, the moon we see is 1.7 seconds in the past because light from the moon takes 1.7 seconds to reach the earth. The sun wee see is 8 minutes in the past because, you know, you get the math, right? If you see person in front of you, that person is also in the past, only marginally and it would not make that big difference because the speed of light is, well, the fastest thing in the universe.
If you were on a planet 200 million light years away from earth right now, you would the super-continent Pangaea which existed on the Earth 200 million years ago
I think it easily should make sense to you now. The light from earth will reach that distant planet only after 200 million years. So, a person standing there right now would be seeing the light that left the earth 200 million years ago.
The closest galaxy is 42000 light years away from us
Canis Major Dwarf Galaxy, the closest galaxy to ours is 42000 light years away us. Meaning it would take 42000 years at the speed of light to reach there. If we ever wanna visit that galaxy, we need to go way faster than the speed of light.
If your child takes immense interest in science and technological facts, then make sure to teach them all the planet facts that I wrote earlier.
Now you know how slow the speed of light is when we compare interstellar distances. To travel across the universe in one lifetime, we have to go faster than the speed of light.