随着美国、韩国和欧盟准备发射能够监测污染物和其他气溶胶的卫星，一项空气质量的监测正在全球进行。 访问 http://science.nasa.gov/ 了解更多信息。 点击这里查看更多视频：https://alugha.com/NASA
Visit http://science.nasa.gov/ for more. Earth is surrounded by electrons that can be disruptive to our technology. NASA is using high-altitude balloons and spacecraft to monitor and understand these particles in the radiation belts surrounding our planet. Click here to see more videos: https://al
Explore how astronomers and scientists use astronomical units to measure distances in the solar system in this video adapted from NASA. The astronomical unit (au) -- equal to the average distance from Earth to the Sun -- is a convenient unit of measure when talking about distances in the solar syste
