Read the text again and answer the following questions.
1. What are humans still wondering nowadays?
2. Why does a habitable planet need to have the correct amount of air?
3. What happens if a planet is too small?
4. How long does a day on Mars last?
5. Why can we not live on Mars?
THE TEXT:
Nowadays humans are still wondering what planets in outer space might support life.
Scientists say planets need to meet three main conditions to support life. Firstly, they must have liquid water, so their temperature must not be too high or too low. Secondly, the planets need to have the correct amount of air so that they can hold an atmosphere around. Finally, their size is also important. If a planet is too small, its gravity is not strong enough to hold an enough amount of air. If it is too big, its gravity will be so strong that it will hold too much air.
Scientists are using space telescopes to find habitable planets. According to them, Mars is one of the most promising planets for life in our solar system. It is a planet like Earth. Its days last for 24.5 hours and its seasons are similar to Earth's. Although scientists have not found actual water on Mars, there seems to be traces of it on the planet's surface. However, the climate on Mars is unsuitable for human life because it is too cold and Mars lacks oxygen to support human life.
1. They are still wondering what planets in outer space might support life.
2. It needs to have the correct amount of air to hold an atmosphere around it.
3. Its gravity is not strong enough to hold an enough amount of air.
4. Its day lasts for 24.5 hours.
5. Because it is too cold and lacks oxygen.
