Is there intelligent life(智能生命) on other planets(行星)? 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(宇宙). They also think we still soon communicate with these beings(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(星系),” says Shostak. “And our galaxy, the Milky Way, has at least 100 billion stars. Some planets going around these stars might be similar to Earth.”

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

Have beings from space already visited Earth? “Probably not,” says Shostak. “It’s a long way away. However, intelligent beings may contact(联系) us in other way, such as radio signals. 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.”

One of the most detailed descriptions of a UFO was given by nine-year-old Gaynor Sunderland in July 1976. Gaynor lived in Oakenholt, a village in North Wales. On her way home from school, she saw a silver object shaped like a saucer (茶碟) in a field not far from her home.

The strange craft (飞行物) was about 30 feet long and 9 feet high. It had yellow windows along the side and on the top there was a light flashing in a kind of box. Although Gaynor was very frightened, she did not run away. Instead, she lay quietly in the long grass and watched the door of the strange craft open. She saw two people wearing silver suits come out of the craft. They were carrying some kind of equipment (设备) which they used to examine the ground. They were short and had large pink eyes, Gaynor reported.

After about half an hour, the two people went back into the craft. At once there was a loud noise and the UFO took off.

Although Gaynor told her mother what she had seen, her family decided to keep quiet about it. They did not want people to laugh at their daughter. However, 18 months later, Gaynor told her story to UFO experts. They hypnotized (使人进入睡眠状态) Gaynor so that they could be sure she was telling the truth.

Not only did she repeat her story, but also she was able to draw a picture of what she had seen!

There is a new sight in the sky these days —the newly-discovered Comet (彗星) NEOWISE is flying past the sun. This the first time since the 1990s when people have had a chance to see a comet with their bare eyes (裸眼).

A comet is basically a ball of dirty ice that moves around the sun. As a comet comes close to the sum, the sun melts some of the ice, which makes a tail behind the comet as it flies through space. Most comets move around the sun in a circle. Comets spend most of their time moving slowly, far away from the sun. As they pass the sun, they speed up.

The size and shape of a comets moving way can influence how long it takes to finish its one circle. Halley’s Comet is a famous comet coming around once every 75-76 years. But the last time Comet NEOWISE was here near the sun was about 6, 800 years ago. Because of the long time it takes to finish its one circle, NEO WISE was only just discovered some months ago. It was seen in March with a special space telescope run by NASA.

The name of the telescope system that first saw the comet is NEOWISE, so that’s how the comet got its name. NEOWISE is easy to see now because it is close to the sun. At its farthest, NEO WISE will be 630 times farther away from the sun than the earth is.

Even at its closest—which was on July 23 —the comet was still as far away from the earth as Mars was. But it was still bright enough to see, even without a telescope.