Do you want to celebrate your birthday in space? It would be very different from what you might do on earth. For example, your birthday cake would be flying. The candles could not be lit because astronauts cannot start a fire in the spaceship. Voices are almost the only things that are not changed by being weightless, which means that everything has almost no weight in space.
Some astronauts feel sick for the first few days in space. Some feel as if they have a cold all the time. That's because without gravity(引力), the fluids( 液体) in their bodies move towards their heads. Their faces look a little fatter. .
And because gravity is not pressing on the spine(脊椎). The spine relaxes and stretches(舒展). But when they come back on earth, they shrink(收缩) to their regular height.
Since nothing has weight, astronauts can lift heavy objects easily. However, it is harder to stay still in space than to move around, so the astronauts always hold onto something or tie themselves to something.
| A. For the same reason, their waists get smaller and their chests get bigger. B. They can even lift each other. C. There are pieces of Velcro to stick things in order to keep them from floating around. D. Your friends could still sing Happy Birthday to You. E. Astronauts grow one or two inches in space. F. In space, bone and muscles get weaker. |
