BEIJING, China - The curator of Beijing Planetarium said aliens do exist but they haven't yet come to our planet, xinhuanet.com reported on Tuesday.

Zhu Jin says aliens are likely to be living on some terrestrial planets, explaining that since there are about one trillion planets going around fixed stars like the Earth around the sun, the possibility of our planet being the only one with living creatures is too slim to be true.

But as to the UFO reports, he said they cannot be true. Some so-called UFOs were proved to be planes, kites or other normal objects, and many weird situations can be re-demonstrated.

He also said the distance that the Voyager 1 spacecraft has traveled in the past 33 years only accounts for one-thousandth of the solar system's reach. It will take 10,000 years for human beings to visit planets outside the solar system. So if aliens living in a faraway planet have a similar level of intelligence as human beings, it's impossible for them to travel to Earth.

The best way to find and communicate with aliens is to send radio signals, he added.