Neptune's Mysterious Cloud Disappearance Solved: Solar Cycle Connection Revealed

All Pic Credit - NASA solar system exploration

Astronomers have observed a mysterious phenomenon on Neptune involving its vanishing ice giant clouds.

A patch of cirrus-like clouds remains over Neptune's south pole, while most of the clouds disappeared four years ago.

recent study utilizing nearly three decades of Neptune observations from three space telescopes suggests a connection between the solar cycle and the cloud abundance.

Senior study author Imke de Pater, a professor emeritus of astronomy at the University of California, Berkeley, stated that the data supports the theory of a photochemical reaction triggered by the Sun's ultraviolet rays producing Neptune's clouds.

The solar cycle involves changes in the sun's dynamic magnetic fields over an 11-year period, leading to variations in ultraviolet radiation.

Observations from NASA's Hubble Space Telescope, W.M. Keck Observatory, and Lick Observatory revealed cloud activity cycles spanning 29 years, with Neptune's reflectivity increasing in 2002, dimming in 2007, brightening in 2015, and then fading significantly in 2020.

Lead author Erandi Chavez, a doctoral student at the Center for Astrophysics, Harvard & Smithsonian, noted that the cloud levels still haven't fully recovered four years later.

The study discovered that two years after the solar cycle's peak, more clouds formed on Neptune, and their presence increased the planet's brightness due to sunlight reflection.

The connection between increased sun brightness and cloud formation contradicts the idea of Neptune's four seasons each lasting about 40 years.

The research not only advances understanding of Neptune's climate but also aids in comprehending exoplanets with similarities to Neptune, highlighting the need for continued monitoring of solar system planets to build a reliable dataset for probing periodic variations.