On the International Space Station (ISS), astronauts experience a zero-g environment where they float, and there is no 'up' or 'down'. Water will form blobs instead of falling, and candles will burn outwards rather than upwards.

Why do astronauts on the ISS experience zero-g's?

Question 2 options:

1. Because they are so far away from the Earth that the Earth's gravity can't reach them at all.

2. The space station and the astronauts inside it are always falling down, but since they both fall down at the same rate, the astronauts float inside the station.

3. The ISS is a hoax, filmed in Hollywood. Things appear to float only because of some special effects added in with computer graphics.

4. Because they are so far away from the Earth, the force of Earth's gravity is too small to notice.