NASA Astronomy Picture of the Day 17 April 2023: Stunning red ring of ELVES

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There are various phenomena which light up our sky, the most common being auroras. But auroras or Northern Lights aren't the only phenomenon which can mesmerize people. Transient Luminous Events (TLE), commonly known as Upper-atmospheric lightning also take place in the sky. TLEs are brief occurrences of luminous plasma induced by electricity which takes place at a higher altitude than regular lightning. According to NASA, TLE includes colorful phenomena with names that seem straight out of mythical tales - sprites, elves, and giants.

Today's NASA Astronomy Picture of the Day is a snapshot of ELVES lighting up the sky over Italy, a distinct type of transient luminous event. ELVES refers to Emission of Light and Very Low Frequency perturbations due to Electromagnetic Pulse Sources. This phenomenon occurs in the ionosphere 100 kilometers above the surface and results in visually stunning ring-shaped glows that can expand as much as 400 kilometers (about the length of New York State) in diameter.

The red ELVES captured in the image had a radius of approximately 350 kilometers and occurred at an altitude of about 100 kilometers above the surface, according to NASA. It was captured above Ancona in Italy in March this year.

The picture was captured by astrophotographer Valter Binotto.

What's that red ring in the sky? Lightning. The most commonly seen type of lightning involves flashes of bright white light between clouds. Over the past 50 years, though, other types of upper-atmospheric lightning have been confirmed, including red sprites and blue jets. Less well known and harder to photograph is a different type of upper atmospheric lightning known as ELVES. ELVES are thought to be created when an electromagnetic pulse shoots