One day an Australian farmer Joe saw a bright light in the sky. The light came nearer and nearer and suddenly Joe saw that it was a spaceship. The spaceship landed in a field quickly.

    The door of the spaceship opened and two strange beings climbed out. Joe was afraid of them. He tried to run away. But the spacemen walked towards him, picked him up and carried him into the spaceship. They put wires from a machine onto his head and then they could speak to him in English.

    They asked him questions about the Earth. "We're from Venus（金星）," they said, "but it is getting very hot there. A lot of our people are dying and we haven't much time left. We are trying to find a new home."

    After some time they freed Joe and at last the spaceship took off and could not be seen.

    Joe told his friends about the spacemen, but no one believed his story." You'll believe me one day, "Joe told them." The spacemen will come back..."

    Stonehenge, a rock circle, is one of Britain's greatest mysteries. Every year it （接待，接受） more than 750, 000 visitors. People like to go to this place in June to see the sun rising on the longest day of the year.

    For many years, historians thought Stonehenge was a temple where ancient （领袖） tried to communicate with the gods. Another popular （意见，想法） is that Stonehenge might be a kind of calendar. The large stone were （放） together in a certain way. On midsummer's morning, the sun shines directly into the （中心） of the stone. Other people believe the stones have a （医疗的） use. They think the stones can （阻止） illness and keep people healthy." As you walk there, you can feel the （力量，精力）from your feet move up your body, "said one visitor. No one is sure what Stonehenge was used for, but most agree that the（位置，地方） of the stones must be for a special（目的） .

    Is there intelligent（有智力的） life on other planets? For years, scientists said "no" or "we don't know". But today this is changing. Seth Shostak and Alexandra Barnett are astronomers（天文学家）. They believe intelligent life exists（存在） somewhere in the universe. They also think we will soon contact these beings（人生物）.

    Why do Shostak and Barnett think intelligent life exists on other planets? The first reason is time. Scientists believe the universe is about 12 billion years old." This is long enough for other planets to have intelligent life," say Shostak and Barnett. The second reason is size-the universe is huge." Tools like the Hubble Telescope（哈勃望远镜） have shown that there are at least 100 billion galaxies," says Shostak. "And our galaxy, the Milky Way, has at least 100 billion stars.

    Some planets going around these stars might be similar to the Earth."

    In the past, it was hard to look for signs of intelligent life in the universe. But now, powerful telescopes（高倍望远镜） allow scientists to discover smaller planets-the size of Mars or the Earth-in other solar systems. These planets might have intelligent life.

    Have beings from space already visited the Earth?" Probably not," says Shostak. "It's a long way away. However, intelligent beings may contact us in other ways, such as radio signals（信号）. In fact, they may be trying to communicate with us now, but we don't have the right tools to receive their messages. However, this is changing. By 2025, we could make contact with other life forms in our universe and we might help each other."