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Understanding the Sun (Axios)

4 August 2023


Axios Space: Understanding the Sun
By: Miriam Kramer
Date: 18 July 2023

The Sun’s activity is defying forecasts and highlighting how difficult it is to predict the machinations of Earth’s nearest star.

Why it matters: Space weather, which is largely driven by the Sun, can shorten the lifespans of satellites, cause radio blackouts and, in extreme solar storms, bring down power grids.

  • Predicting and understanding the inner workings of the Sun is key to figuring out how it might behave in the short and long term.

Driving the news: Predictions from 2020 suggested the Sun would reach the peak of its 11-year solar cycle in 2025, and its intensity would be on par with the last cycle.

  • But current observations show its activity could now peak as early as 2024.
  • The current cycle is also on track to be more extreme, with more solar flares, sunspots and activity than the previous one, though not as big as others on record.

How it works: The National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC) is responsible for predicting and forecasting space weather on any given day.

  • The SWPC uses instruments in space and on Earth to gather data about the electrically charged solar plasma constantly emitted by the Sun.
  • Sunspots — dark areas on the face of the Sun — can spit out major solar flares that sometimes come with coronal mass ejections (CMEs), bursts of electrically charged plasma that can interfere with satellites, electrical grids and supercharge the auroras.
  • If coronal holes — cooler spots in the Sun’s atmosphere — rotate into the view of Earth, they can send extremely fast solar winds into our part of space, warping Earth’s magnetic fields in the process.

Yes, but: The Sun is extremely complicated and even after decades of study, researchers don’t understand exactly how it works.

  • “When you see a big sunspot, what’s the chance that it’s going to erupt and give us a big solar flare and coronal mass ejection?” NASA scientist Alex Young tells me. “We don’t understand the factors that go into what makes it release its energy.”

The intrigue: Forecasters also have trouble predicting what the basic impacts of any given solar storm could be.

  • Scientists know the magnetic orientation of a CME determines whether it will strongly interact with Earth’s magnetic field, causing potential problems. However, when a CME erupts, scientists aren’t able to figure out its magnetic orientation immediately.
  • It typically takes a day or so for a CME to travel the 93 million miles to Earth, and scientists today don’t have the technology to predict a CME’s impact until it reaches the satellites stationed about 1 million miles from our planet.
  • “It can take somewhere between 20 minutes to an hour” for a CME to reach Earth from 1 million miles away, Young said, adding that it’s enough time for power companies to make some adjustments to protect the grid if needed, but it’s not ideal.

What to watch: NOAA is planning to fly two new instruments to space that should help them keep an eye on the Sun in the coming years.

  • A Sun-focused instrument is slated to launch on the GOES-U weather satellite next year and another instrument will fly in 2025.
  • Eventually, private companies could have a role in providing the data needed to forecast space weather.
  • “Maybe the private sector can fly the spacecraft and sell the data to the government in a more cost-efficient way to do business,” William Murtagh, the program coordinator for the SWPC, tells me.”



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