仰望夜空,繁星点点,地球以外的世界是什么样子?古代天文学家发现有星球会围绕太阳做有规律的运动,于是称它们为“行星”。太阳系中距离太阳最近的行星是水星,因太靠近太阳,且与太阳的分离角小,所以不易看到。在北半球,只能在凌晨或黄昏看到。随着科技日新月异,人类除用眼睛和望远镜看星星外,还可用太空船飞近星星。第一个进入太空的人造飞行器,是1957年由苏联发 Looked up to the night sky, the stars, what is the world outside the earth? Ancient astronomers found that the planet will do regular movements around the sun, so they called “planets.” The planet closest to the sun in the solar system is Mercury. It is not easy to see because it is too close to the sun and has a small separation angle from the sun. In the northern hemisphere, only in the early morning or evening to see. With the ever-changing technology, in addition to using human eyes and telescopes to see the stars, but also spacecraft can fly near the stars. The first manned aircraft to enter space was sent by the Soviet Union in 1957