JAKARTA – The large dark spot on the planet Neptune is a mystery, but astronomers have succeeded in uncovering its existence and finding further clues about its nature and origin.
Armed with Very Large Telescope (VLT) property European Southern Observatory (ESO), astronomers have observed a large dark spot in Neptune’s atmosphere, with a small bright spot unexpectedly close by.
This is the first time that a dark spot on Neptune has been observed with telescopes on Earth. Great spots are a common feature in the atmospheres of the giant planets, the most famous of which is Jupiter’s Great Red Spot.
On Neptune, the dark spot was first spotted by NASA’s Voyager 2 in 1989, before disappearing several years later.
“Since the first discovery of the dark spot, I have always wondered what these short-lived and elusive dark features are,” said the study’s lead researcher, Patrick Irwin.
Irwin and his team used data from the VLT to rule out the possibility that the black spots were caused by clearing in the cloud.
The new observations suggest the dark spots are likely caused by airborne particles darkening in layers below the main visible haze layer, as ice and fog mix in Neptune’s atmosphere.
Reaching this conclusion was not easy because dark spots are not a permanent feature of Neptune’s atmosphere and astronomers have never been able to study them in sufficient detail.
The opportunity arose after NASA and ESA’s Hubble Space Telescope discovered several dark spots in Neptune’s atmosphere, including one in the Northern Hemisphere that was first spotted in 2018.
Afterward, Irwin and his team began studying it from the ground, with instruments suitable for these challenging observations.
By using Multi Unit Spectroscopic Explorer (MUSE) on the VLT, astronomers can divide the reflection of sunlight from Neptune and its points into component colors, or wavelengths, and obtain a 3D spectrum. This means they can study the place in greater detail than before.
“I am very excited because I can not only make the first detection of a dark spot from the ground surface, but also for the first time record the reflection spectrum of this feature,” said Irwin.
Because the wavelengths probing the depths of Neptune’s atmosphere differ, having a spectrum allows astronomers to better determine the height of the dark spot in the planet’s atmosphere.
The spectrum also provides information about the chemical composition of different layers of the atmosphere, which gave the team a clue as to why the spot appears dark. The observations also yielded some surprising results.
“In the process, we discovered a rare type of bright, deep cloud that had never been identified before, even from space,” said study co-author Michael Wong, a researcher at the University of California, Berkeley, US.
This rare cloud type appears as a bright spot immediately beside a larger main dark spot. The VLT data shows the new deep light cloud is at the same level in the atmosphere as the main dark point.
Demonstrating, the feature is an entirely new type of feature compared to previously observed low-altitude methane icy companion small clouds. With the help of VLTs, astronomers can now study features such as points from Earth.
“This is a tremendous improvement in humanity’s ability to observe the cosmos. At first, we could only detect these points by sending spacecraft to them, such as Voyager,” said Wong.
“Then we gained the ability to view it remotely with Hubble. Finally, the technology has advanced to allow this to happen. This could cost me my job as a Hubble observer!,” he continued.
For information, this research is presented in a paper entitled “Structure of Dark Spot Clouds and Storms in Neptune’s Atmosphere” published in Nature Astronomy.
Tags: neptune outer space james webb telescope
2023-08-25 21:00:00
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