Astronomers have successfully mapped the Sun’s shifting atmospheric edge for the first time, a significant development in the field of solar physics. This achievement will enable scientists to better understand the Sun’s atmosphere and its influence on space weather, which affects Earth’s climate and the functioning of satellites.
The Sun’s atmosphere, known as the corona, extends several million kilometers into space. It’s far hotter than the Sun’s surface, reaching temperatures of up to a few million degrees. The corona also emits extreme ultraviolet (EUV) radiation, which can have a significant impact on Earth’s upper atmosphere and space weather.
In the past, researchers lacked the tools to directly measure the lower boundary of the corona, also known as the “transition region.” This area, where the Sun’s atmosphere shifts from the cooler chromosphere to the hotter corona, has remained largely unexplored due to its thin and dynamic nature. However, a team of astronomers led by Dr. Wei Liu from the Bay Area Environmental Research Institute at NASA’s Ames Research Center, has now managed to map this elusive region using data from NASA’s Solar Dynamics Observatory (SDO).
Dr. Liu and his team used a technique known as “differential emission measure tomography” to create a three-dimensional map of the transition region. This technique involves measuring the intensity of EUV light at various wavelengths and then using these measurements to estimate the temperature and density of the solar plasma at different altitudes.
The researchers’ map revealed that the transition region is not uniform but rather fluctuates, moving up and down by several thousand kilometers over periods of just a few minutes. These fluctuations are believed to be caused by magnetic waves in the Sun’s atmosphere, which heat the corona by transferring energy from the Sun’s interior.
The team’s findings have significant implications for our understanding of the Sun and its effects on space weather. By studying the transition region, scientists can gain valuable insights into the processes that heat the corona and drive solar wind, a stream of charged particles that can disrupt satellites and power grids on Earth. The team’s work also paves the way for future solar missions, such as NASA’s upcoming PUNCH mission, which will study the Sun’s outer corona and the heliosphere – the bubble of solar wind particles that extends far beyond the planets.
In sum, the successful mapping of the Sun’s atmospheric edge represents a major breakthrough in solar physics, paving the way for a better understanding of the Sun’s atmosphere and its influence on space weather.
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