NASA Astronomy Picture of the Day 11 January 2023: Auroras spiralling in the Icelandic sky

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Scientists have long studied Auroras to better understand the workings of Earth's magnetic field and the solar wind. Auroras, also known as the Northern and Southern Lights, put on a mesmerizing show of lights in the night skies of the polar regions. Although auroras are usually green in colour, they can appear as pink sometimes too. Green auroras are formed when energy particles hit the oxygen atoms at 100 km to 300 km from the surface of the planet. But when particles hit at a height lower than 100 km, it results in the formation of pink auroras.

NASA's Astronomy Picture of the Day is a mesmerizing snapshot of Spiral Auroras captured over a rock arch in the northwest coast of Iceland. The rock arch is known as Gatklettur where the larger rocks span as long as a meter across. Spiral auroras can be seen canvassing the sky in the shades of green. The image was captured by Stefano Pellegrini, an astrophotographer based in Milan, Italy. Although Pellegrini started astrophotography only in 2019, the pandemic helped him in honing his skills to capture breathtaking stills.

The scene may look like a fantasy, but it's really Iceland. The rock arch is named Gatklettur and located on the island's northwest coast. Some of the larger rocks in the foreground span a meter across. The fog over the rocks is really moving waves averaged over long exposures. The featured image is a composite of several foreground and background shots taken with the same camera and from the same location on the same night last November. The location was picked for its picturesque foreground, but the timing was planned for its colorful background: aurora.

The spiral aurora, far behind the arch, was one of the brightest seen in the astrophotographer's life. The