NASA Observations Unveil Secrets Behind the Heating of ‘Moss’ Roots on the Sun.

In the heart of the solar system, captivating phenomena unfold, such as the enigmatic “moss” discovered by solar physicists. Captured by NASA’s High Resolution Coronal Imager sounding rocket, this small-scale, patchy structure adorns the Sun’s surface, nestled within sunspot groups where magnetic vigor reigns supreme. Complementing this view, imagery from NASA’s Interface Region Imaging Spectrograph (IRIS) mission unveils the intricate roots of moss, offering a closer glimpse into its cooler confines. Together, these snapshots unveil a mesmerizing portrait of the Sun’s dynamic atmosphere, inviting exploration into the mysteries of its magnetic tapestry.

Did you know the Sun has moss? Named for its similarity to earthly plants, scientists have dubbed a peculiar structure in the solar atmosphere “moss.” This patchy, small-scale formation, comprised of plasma, was initially spotted in 1999 during NASA’s TRACE mission. Moss tends to flourish around the core of a sunspot group, where magnetic forces are robust. Positioned between the chromosphere and corona, it remains concealed beneath the intricate coronal loops of plasma.

For decades, scientists have grappled with the perplexing connection between the mossy region of the Sun’s atmosphere and its lower atmospheric layers. The challenge lies in comprehending the remarkable temperature gradient, with materials heating from 10,000 degrees Fahrenheit to nearly 1 million degrees Fahrenheit—a staggering 100-fold increase compared to the bright surface below. Recent advancements, fueled by data from NASA’s High Resolution Coronal Imager (Hi-C) sounding rocket and the Interface Region Imaging Spectrograph (IRIS) mission, have provided invaluable insights into the superheating mechanisms at work within the moss.

Observations from these cutting-edge instruments, coupled with intricate 3D simulations, have unveiled a crucial revelation: electrical currents likely play a role in heating the moss region of the Sun. Within this domain lies a complex web of magnetic field lines akin to invisible spaghetti. This tangled magnetic architecture generates electrical currents, which in turn contribute to heating materials across a vast temperature spectrum, ranging from 10,000 to 1 million degrees Fahrenheit. This localized heating phenomenon within the moss operates in tandem with the heat emanating from the scorching multi-million-degree corona above. The significance of this finding, published in the esteemed journal Nature Astronomy on April 15, extends beyond the confines of the moss itself, offering valuable insights into the broader puzzle of why the Sun’s corona surpasses the surface in temperature.

Thanks to the high-resolution observations and our advanced numerical simulations, we’re able to figure out part of this mystery that’s stumped us for the past quarter of a century,” remarked author Souvik Bose, a research scientist at Lockheed Martin Solar and Astrophysics Laboratory and Bay Area Environmental Institute, NASA’s Ames Research Center in California’s Silicon Valley. “However, this is just a piece of the puzzle; it doesn’t solve the whole problem.” To fully unravel the mysteries surrounding the heating mechanisms of the corona and moss, additional observations are imperative.

Fortunately, upcoming endeavors hold promise: the relaunch of Hi-C later this month aims to capture a solar flare, potentially providing further insights into the moss region alongside IRIS. Additionally, scientists and engineers are diligently crafting new instruments for deployment onboard the future MUlti-slit Solar Explorer (MUSE) mission, heralding a new era of discovery in solar physics.