Astronomers Discover a Large and Mysterious Dark Spot in Neptune’s Atmosphere.
Astronomers have discovered a large and mysterious dark spot in Neptune’s atmosphere. The observation was made using the Very Large Telescope of the European Southern Observatory in Chile.
Neptune appears blue due to methane in its atmosphere.
Space observatories have previously detected swirling storm systems appearing as dark spots in the atmosphere of the blue planet. However, this is the first time that a ground-based telescope has observed a storm on Neptune. The study was published in the journal Nature Astronomy.
Mr. Patrick Irwin, a planetary physicist at the University of Oxford (UK), stated: “Since the first discovery of a dark spot, I have always wondered what these short-lived and elusive features are.”
The giant gas planets in our Solar System, including Neptune, are known for their dark spots appearing in their atmospheres. Neptune—a giant icy planet—has experienced many storms over the years. These storms appear to follow a pattern of appearing and disappearing over two years.
This makes studying them challenging. Voyager 2, a NASA probe launched in the 1970s, also observed two dark storms on Neptune in 1989. The large dark spot on Neptune—nicknamed the Great Dark Spot—was the largest storm that Voyager 2 witnessed, large enough to fit the entire Earth.
Neptune’s storms behave differently than those on Earth. The dark spots are high-pressure systems that begin to stabilize and rotate clockwise. In contrast, storms in Earth’s Northern Hemisphere are low-pressure systems that rotate counterclockwise. What Irwin and his team want to understand is how these large storms on Neptune form.
Neptune is blue due to methane in its atmosphere. It is a frozen world with an average temperature of minus 392 degrees F (minus 235 degrees C) and screaming winds that send methane clouds swirling across the planet at speeds of 1,200 miles per hour (1,931 kilometers per hour).
This is the farthest planet in our Solar System, approximately 30 times the distance from the Sun compared to Earth. This distance makes midday on Neptune resemble sunset on Earth.
The collected data has helped astronomers determine that the dark spots are not caused by gaps in the cloud. Instead, observations show that the dark spots appear when particles of dark air gradually concentrate beneath Neptune’s prominent atmospheric layer, where fog and ice intermingle.
Co-author of the study, Michael Wong, a planetary scientist at the University of California, Berkeley (USA), stated: “During this process, we discovered a rare type of cloud that has never been identified before, even from space.”
Astronomers have expressed great interest in this new feature. The team hopes to learn more through future observations that may be conducted from Earth.
