Study: Neptune’s Disappearing Clouds Linked to Solar Cycle

2023 · VOA Learning English

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1. Scientists say they have discovered new evidence that cloud activity on Neptune is linked to atmospheric changes on the planet caused by the

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2. sun. Researchers say the evidence is based on observations collected by several telescopes over a period of nearly 30 years.

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3. Data was collected by the Hubble Space Telescope operated by the American space agency NASA as well as the W.M.

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4. Keck Observatory in Hawaii and the Lick Observatory in California. Astronomers recorded atmospheric changes on Neptune as they examined the cloud data.

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5. The researchers found that the changes followed the sun’s natural cycle.

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6. Each natural cycle known as the solar cycle, lasts about 11 years. During this cycle, the sun’s magnetic field completely flips

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7. This means the sun’s north and south magnetic poles change places. They then flip back after another 11 years.

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8. Before the flip, a major increase in solar activity happens. This can send powerful collections of solar particles shooting through space.

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9. The scientists who examined the telescope data said they found that Neptune appeared brightest in 2002, then dimmed in 2007.

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10. The planet became bright again in 2015, but then darkened in 2020 to the dimmest level ever observed.

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11. The team said the observations also showed Neptune lost nearly all of its clouds beginning in 2019.

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12. Astronomers at the University of California, Berkeley (UC Berkeley) led the research. They recently reported their findings in a study in the publication Icarus

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13. Imke de Pater is a retired professor of astronomy at UC Berkeley and was the lead writer of the study.

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14. She said in a statement she was surprised by how quickly clouds disappeared on Neptune. She noted cloud activity had dropped sharply “within a few months.”

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15. “Even four years later, the images we took this past June showed the clouds haven’t returned to their former levels,” said Erandi Chavez.

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16. She is a student at Harvard University’s Center for Astrophysics who took part in the study while at UC Berkeley.

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17. “This is extremely exciting and unexpected,” Chavez said.

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18. She noted the finding was unusual “since Neptune’s previous period of low cloud activity was not nearly as dramatic and prolonged

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19. Neptune, about four times wider than Earth, is the eighth and most distant major planet orbiting our sun, NASA says

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20. It receives sunlight with only about 0.1 percent intensity of our planet.

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21. For this reason, the researchers found it surprising that Neptune would be heavily influenced by solar activity.

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22. The planet also receives intense winds that can blow around clouds. The scientists looked at images captured by the different telescopes.

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23. They discovered clear patterns between seasonal changes in Neptune’s cloud cover and the solar cycle.

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24. The team found that during periods when the sun gave off more intense ultraviolet (UV) light, more clouds appeared on the planet two years later.

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25. De Pater said the newly discovered data provides "the strongest evidence yet that Neptune's cloud cover correlates with the sun’s cycle."

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26. He added the findings "support the theory that the sun's UV rays, when strong enough, may be triggering a photochemical reaction that produces Neptune’s clouds."

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27. Photochemical is a term relating to how chemicals are affected by light. The researchers are continuing to follow cloud activity on Neptune.

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28. They noted that the latest images taken of the planet, in June 2023, showed clouds started to return.

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29. The team says this finding further strengthens their evidence.

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30. This is because the scientists see a link between the increasing cloud cover and the release of intense UV light over the past two years.

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31. The researchers say further study is needed to confirm their latest results.

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32. They say the research will be important not only for learning more about Neptune, but can also help scientists gain a better understanding of how similar planets outside our

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33. solar system behave. I’m Bryan Lynn.

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