Tuesday, July 23, 2024

A mysterious dark spot on Neptune has been detected from Earth for the first time

This image shows Neptune observed with the MUSE instrument on ESO’s Very Large Telescope (VLT). At each pixel on Neptune, MUSE separates the incoming light into its constituent colors, or wavelengths. This is similar to acquiring images at thousands of different wavelengths simultaneously, providing valuable information to astronomers. Credit: ESO/P. Irwin et al.

Astronomers using the European Southern Observatory A very large telescope (VLT) has identified a significant dark spot NeptuneAtmospheric, with little bright spot nearby. This was the first observation made by a ground-based telescope.

Using the European Southern Observatory’s Very Large Telescope (VLT), astronomers have discovered a large dark spot in Neptune’s atmosphere, with an unexpectedly small bright spot adjacent to it. This is the first time that a black spot on a planet has been seen through a telescope on Earth. These occasional features against the blue background of Neptune’s atmosphere are a mystery to astronomers, and the new results provide more clues about their nature and origin.

Large spots are common features in the atmospheres of giant planets, and are the most famous ThursdayBig red dot. On Neptune, a dark spot was first discovered NASAVoyager 2 in 1989 and disappeared a few years later. “Since the first discovery of a dark spot, I have always wondered what these short-lived and elusive dark features are,” says Professor Patrick Irwin. University of Oxford in the UK and was the principal investigator of the study published on August 24 Natural Astronomy.

Using That‘s Very Large Telescope (VLT), astronomers have observed a large dark spot in Neptune’s atmosphere, with an unexpectedly small bright spot adjacent to it. This short video summarizes their findings. Credit: ESO

Findings from observations

Irwin and his team used data from ESO’s VLT to rule out the possibility that black spots are caused by ‘clearness’ in clouds. The new observations indicate that dark spots may result from the darkening of air particles in a layer below the mainly visible fog layer as ice and fog mix in Neptune’s atmosphere.

Coming to this conclusion is not an easy task because dark spots are not permanent features in Neptune’s atmosphere. That opportunity came after NASA/ESA Hubble Space Telescope They discovered several dark spots in Neptune’s atmosphere, including one in the planet’s northern hemisphere that was first observed in 2018. Irvine and his team immediately set to work studying it from the ground up—with an instrument well-suited to these challenging observations.

Using the VLT’s Multi-Unit Spectroscopic Explorer (Muse), researchers were able to separate the reflected sunlight from Neptune and its orbit into its component colors, or wavelengths, to obtain a 3D spectrum.[1] This means they can read the space in more detail than before. “I am very excited to not only be the first to detect a dark spot from the ground, but also to be able to record the reflectance spectrum of such a feature for the first time,” says Irwin.

Neptune Natural View Muse

This image shows Neptune as seen with the MUSE instrument on ESO’s Very Large Telescope. At each pixel on Neptune, MUSE separates the incoming light into its constituent colors, or wavelengths. This is similar to acquiring images at thousands of different wavelengths simultaneously, providing valuable information to astronomers. This image combines all the colors captured by MUSE into a “natural” view of Neptune, where a dark spot can be seen in the upper right. Credit: ESO/P. Irwin et al.

Importance of spectrum analysis

Because different wavelengths probe different depths in Neptune’s atmosphere, the spectrum allows astronomers to better determine how high up in the planet’s atmosphere the dark spot is. The spectrum also provided information about the chemical composition of different layers of the atmosphere, which gave the team clues as to why the space appeared dark.

The observations also yielded a surprising result. “In the process, we discovered a rare type of deep bright cloud that has never been identified, even from space,” says study co-author Michael Wong. University of California, Berkeley, America. This rare cloud type appeared as a bright spot near the Great Main Dark Spot, with VLT data showing a new ‘deep bright cloud’ in the atmosphere at the same level as the main dark spot. This is an entirely new type of feature compared to the smaller ‘companion’ clouds of high-altitude methane ice seen before.

This animation shows Neptune observed with the MUSE instrument at ESO’s Very Large Telescope. At each pixel on Neptune, MUSE separates the incoming light into its constituent colors, or wavelengths. This is similar to acquiring images at thousands of different wavelengths simultaneously, providing valuable information to astronomers. In this animation, we scan all these different wavelengths and reveal different dark and bright features. Based on the wavelengths at which these features are most prominent, astronomers can determine what causes them and how deep in Neptune’s atmosphere they are located. Credit: ESO/P. Irwin et al./L. Pants

Implications for future observations

With the help of ESO’s VLT, it is now possible for astronomers to study these dot-like features from Earth. “It’s an amazing increase in humanity’s ability to observe the universe. At first, we could only detect these points by sending a spacecraft like Voyager. Then we got the ability to take them out remotely with Hubble. Finally, the technology has advanced to do this from the ground,” Wong added, before jokingly adding. Concludes: “This may put me out of work as a Hubble observer!”

This animation shows Neptune observed with the MUSE instrument at ESO’s Very Large Telescope. At each pixel on Neptune, MUSE separates the incoming light into its constituent colors, or wavelengths. This is similar to acquiring images at thousands of different wavelengths simultaneously, providing valuable information to astronomers.

The first image in this animation combines all the colors captured by MUSE into a “natural” view of Neptune, where a dark spot can be seen in the upper right. Then we look at images at specific wavelengths: 551 nanometers (blue), 831 nm (green), and 848 nm (red); Note that colors are for display purposes only.

The dark spot is most prominent at shorter (blue) wavelengths. Next to this dark spot MUSE also captured a small bright one, seen here in the middle image only at 831 nm and located deep in the atmosphere. This type of deep bright cloud has never been identified before on the planet. The images also show several shallow bright spots at longer wavelengths toward Neptune’s lower-left edge.

Only the VLT’s adaptive optics facility, which allows MUSE to obtain crystal-clear images by correcting for blur caused by atmospheric turbulence, was able to image Neptune’s dark spot. To better highlight the planet’s subtle dark and bright features, astronomers carefully processed the MUSE data to get what you see here.

Credit: ESO/P. Irwin et al.

Notes

  1. MUSE is a 3D spectrograph that allows astronomers to simultaneously observe an astronomical object like Neptune. At each pixel, the instrument measures the intensity of light as a function of its color or wavelength. The resulting data creates a 3D set in which each pixel of the image contains the entire spectrum of light. In total, MUSE measures more than 3500 colors. The instrument is designed to take advantage of adaptive optics, which corrects for turbulence in Earth’s atmosphere, resulting in sharper images than otherwise possible. Without the combination of these features, studying Neptune’s dark spot from the ground would be impossible.

Reference: Patrick GJ Irwin, Jack Dobinson, Arjuna James, Michael H. Wong, Lee N. Fletcher, Michael D. Roman, Nicholas A. Deanby, Daniel Toledo, Glenn S. Orton, James Perez-Holz, Agustin Sanchez-LaVega, Lawrence Sromowski, Amy A. Simon, Raul Morales-Juberias, Imke de Pater, and Stadia L. Cook, August 24, Natural Astronomy.
DOI: 10.1038/s41550-023-02047-0

Committee Patrick GJ Irwin (University of Oxford, UK [Oxford]), Jack Dobinson (Oxford), Arjuna James (Oxford), Michael H. Wong (University of California, USA [Berkeley]), Lee N. Fletcher (University of Leicester, UK [Leicester]), Michael D. Roman (Leicester), Nicholas A. Deanby (University of BristolUK), Daniel Toledo (National Institute of Aerospace Technique, Spain), Glenn S. Orton (Jet Propulsion Laboratory, USA), Santiago Pérez-Hoyos (University of the Basque Country, Spain). [UPV/EHU]Agustín Sánchez LaVega (UPV/EHU), Lawrence Sromowski (University of Wisconsin, USA), Amy Simon (Solar Family Studies Division, NASA Goddard Space Flight Center, USA), and Raul Morales-Juberias (New Mexico Institute of Technology, USA). ), Imke de Pater (Berkeley), and Stadia L. Cook (Columbia UniversityAmerica).

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