Why do stars twinkle?

Now that it’s winter and the sun sets much earlier in the day, you may start to notice objects in the night sky you didn’t see before. It can be a shock to see bright flashing lights low in the sky, just above the horizon, that look like UFOs!

Space Exploration: History and Challenges

Since time immemorial, humans have been fascinated with flight. However, it wasn’t until the industrial revolution that we created the means to do so.