Understanding Scale in Space
One of the hardest things about space is understanding its scale. Everything we experience on Earth happens on human-sized distances, but space operates on distances that are truly enormous.
For example:
You could fit over 1 million Earths inside the Sun
Light takes 8 minutes to travel from the Sun to Earth
Light takes over 4 years to reach the nearest star system
Why We Use Light-Years
Distances in space are so vast that kilometres or miles become impractical. Instead, astronomers use light-years, which measure distance, not time.
One light-year = the distance light travels in one year
≈ 9.46 trillion kilometres
So when a star is 100 light-years away, the light you see tonight left that star 100 years ago.
The Observable Universe
The universe is estimated to be 13.8 billion years old, but because space itself is expanding, the observable universe is about 93 billion light-years across.
Beyond that?
We don’t know what exists
Light hasn’t had time to reach us
The universe may be infinite
Why Space Feels Empty
Despite containing billions of galaxies, space feels empty because matter is spread incredibly thinly. Galaxies themselves are separated by vast cosmic voids.
Key Takeaways
Space distances are unimaginably large
Light-years measure distance, not time
We only see part of the universe