Extra-terrestrial beings do exist but they have not yet come to visit our planet, and the best way to communicate with aliens is to send radio signals, a top Chinese official said Tuesday.

Zhu Jin, curator of the Beijing Planetarium, said aliens are likely to be present on some planets. Since there are about one trillion planets going around fixed stars, the possibility of the earth being the only planet with living creatures was "too slim to be true", China Daily reported.