Reading - Part 1

Read the text. Fill in each gap with ONE word. You must use a word which is somewhere in the rest of the text.

Looking for a new Earth

For thousands of years, humans have explored the Earth. Nowadays, we are exploring space. Astronomers are the modern-day explorers. Currently, many (1) are looking for new planets and new places for humans to live in the future. But where do astronomers start looking? First of all, astronomers look for a star. That's because our own Earth orbits a star (the Sun). More importantly, it is the correct distance from the Sun for heat and light. So when astronomers have found the (2), they look at the planets around it. In recent years, astronomers have found nearly 400 new planets with stars. Unfortunately, many of these (3) are either too near to the star or too far away. However, if the planet is in a good position, astronomers (4) for three key things: water, air and rock. Water is important because all life needs water. Humans can drink it and they can also grow plants with water. And (5) produce air for humans to breathe and food to eat. So all life on other planets will need water and air. (6) on a planet is also important. That's because there is often water under the rocks.