Wednesday, February 25, 2015

A Full Circle Rainbow over Australia

A Full Circle Rainbow over Australia: APOD: 2014 September 30 - A Full Circle Rainbow over Australia

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2014 September 30

See Explanation. Clicking on the picture will download the highest resolution version available.
Explanation: Have you ever seen an entire rainbow? From the ground, typically, only the top portion of a rainbow is visible because directions toward the ground have fewer raindrops. From the air, though, the entire 360 degree circle of a rainbow is more commonly visible. Pictured here, a full circle rainbow was captured over Cottesloe Beach near Perth, Australia last year by a helicopter flying between a setting sun and a downpour. An observer-dependent phenomenon primarily caused by the internal reflection of sunlight by raindrops, the 84-degree diameter rainbow followed the helicopter, intact, for about 5 kilometers. As a bonus, a second rainbow that was more faint and color-reversed was visible outside the first.