General Space Facts

General Space Facts

1. Outer Space Begins at the Kármán Line
   This imaginary boundary is 100 kilometers (62 miles) above sea level — officially marking the start of outer space.

2. Space Is a Vacuum
   There’s no air, which means no weather, no sound, and extreme temperatures — boiling hot in sunlight, freezing cold in shadow.

3. Space Smells Odd (in a suit)
   Astronauts report that after spacewalks, their suits smell like seared steak, welding fumes, or gunpowder. This is due to high-energy particles clinging to the suit and oxidizing on re-entry.

4. Time Passes Differently in Space
   Due to the effects of gravity and motion (relativity), time moves slightly slower in stronger gravity. This has been confirmed with GPS satellites and astronauts in orbit.

5. The Universe Is Expanding
   Galaxies are moving away from each other as space itself stretches — a discovery credited to Edwin Hubble. The farther away a galaxy is, the faster it’s receding.

6. Most of the Universe Is Invisible
   About 68% is dark energy, 27% is dark matter, and only ~5% is normal matter — what we can see and measure directly.

7. Space Is Mostly Empty, But Not Entirely
   Even in the vast voids between stars, there are stray atoms, radiation, and cosmic dust. This is called the interstellar medium.

8. The Speed of Light Is the Cosmic Speed Limit
   Light travels at about 300,000 km/s (186,000 miles/s). At that speed, it still takes light 8 minutes to reach Earth from the Sun.

9. No Direction Is “Up” in Space
   There’s no absolute up or down in space. Directions are relative and often defined by gravitational forces or celestial bodies.

10. The Coldest Known Place in the Universe
    The Boomerang Nebula is about -272°C (1 Kelvin), even colder than the background temperature of space.