Siriusly twinkling
If you live nearly anywhere on Earth and look to the southeast shortly after sunset, you’ll see the figure of Orion. Follow the three belt stars to the east, and you’ll see a bright star: Sirius, the brightest star in the night sky. If it’s near the horizon, you may see it twinkling madly: flickering, dancing, perhaps even changing color.
This gave astronomer David Lynch an idea: take a time exposure of Sirius with a camera and telephoto, and purposely wiggle the mount. He tried it on January 4, 2012, and the result is the picture shown above.
As the vibrating camera caused the star to trail around, the changing colors got recorded along the track. The changing brightness of Sirius can be seen as well, as parts of the loop-de-loop fade and intensify.
The reason stars twinkle is because of our atmosphere: little blobs of air are constantly in motion. These air parcels act like lenses, and as light passes through them, the path of the ray gets bent a little bit. That’s what causes the dancing motion, the actual twinkling.
