Chapter 1: The Dark Side of Neptune

While Jupiter’s Great Red Spot often steals the spotlight, recent observations have turned attention towards Neptune and its atmospheric phenomena. Astronomers have been tracking the formation of dark vortexes in the ice giant’s clouds over the years, and a significant one has recently been observed. Understanding the emergence of these storms is crucial for comprehending Neptune’s atmospheric dynamics.

NASA reported the initial sighting of this dark vortex alongside a white cap on Uranus earlier this year as part of the Outer Planet Atmospheres Legacy (OPAL) initiative. A comprehensive report detailing this vortex has now been released.

The first insights into Neptune's dark spots emerged during Voyager 2's fly-by in 1989, which revealed two vortexes, one of which held the record for the largest at that time. Since the early 1990s, NASA's Hubble Space Telescope has identified four additional dark vortexes on Neptune. These massive storms, including the latest one comparable in size to Earth, are transient, existing for only a few years, in stark contrast to Jupiter’s enduring red spot, which has persisted for centuries.

Previous dark vortexes had been found fully formed, but this new one was discovered in its infancy. Researchers Michael Wong and Andrew Hsu from the University of California, Berkeley, were examining Hubble images from the last dark spot observed in 2017 when they spotted some small, bright clouds nearby. These clouds soon darkened and developed into the 2018 vortex.

The bright clouds were identified as methane ice crystals, and atmospheric modeling indicates that these companion clouds intensify in brightness as the storm deepens. The researchers estimate that wind speeds at the vortex's core could be four times stronger than those at the surface, reaching up to 100 meters per second (328 feet per second), comparable to the winds in Jupiter's Great Red Spot.

NASA intends to monitor the 2018 vortex as long as possible. Unlike the Great Red Spot, the vortexes on Neptune are mobile, complicating tracking efforts from Earth. Ideally, researchers would prefer a satellite orbiting Neptune, but the lifespan of the current vortex is projected to be no longer than six years—consistent with the duration of prior storms on Neptune. However, new dark vortexes typically emerge every four to six years.

The first video titled "Dark Spot On Neptune Did Something Unexpected and Hard to Explain" explores the unusual characteristics of this newly formed dark vortex and its implications for our understanding of Neptune’s atmosphere.

The second video, "Hubble Watches Neptune's Dark Storm Die," documents Hubble's observations of the life cycle of Neptune's storms, providing insights into how these atmospheric phenomena evolve over time.

Now read: NASA's Innovative Solutions to Restore Hubble's Functionality, Hubble's Close Encounter with Mars and Saturn, and Hubble's Exploration of Ancient Galaxies in the Universe.

Originally published at www.extremetech.com on March 27, 2019.