China deploys advanced solar telescope to measure magnetic fields with unprecedented accuracy

China deploys advanced solar telescope to measure magnetic fields with unprecedented accuracy

by Riko Seibo

Tokyo, Japan (SPX) Oct 24, 2025

The Accurate Infrared Magnetic Field Measurements of the Sun (AIMS) is now operational in Lenghu township, Qinghai province, at approximately 4,000 meters altitude. This solar magnetic-field telescope is the first in the world to function in the mid-infrared wavelength range, marking significant progress in the direct measurement of the sun’s magnetic field.

For decades, measurements relied on indirect methods, limiting precision. AIMS was developed to overcome these challenges, advancing from a traditional 100-gauss precision to measurements better than 10-gauss accuracy. Deng Yuanyong of the National Astronomical Observatories of the Chinese Academy of Sciences, who led the project, affirmed, “The sun, being the only star we can observe with high precision, has a magnetic field that acts as the energy switch driving intense solar activities such as flares and coronal mass ejections. Yet, more than half the sun’s overall magnetic field manifestations are relatively weak, with strengths of only a few dozen gauss.”

All core components of the telescope are domestically produced, contributing to China’s capabilities in astronomical instrument innovation. The telescope uses an off-axis optical system to reduce interference from the high environmental background of the mid-infrared range and integrates cooling and filtering technologies to boost magnetic field measurement accuracy.

AIMS features an infrared-separating spectrograph for high-resolution spectral imaging of the solar atmosphere. The team also created a novel polarization modulation technique and a polarization-aberration-free optical system using five reflective mirrors to minimize instrumental errors. Deng Yuanyong stated, “It is the world’s first solar magnetic-field telescope operating in the mid-infrared wavelength range and China’s first astronomical instrument to work in this band.”

The new facility expects about 250 days of observation annually, weather permitting, with data anticipated to support solar physics research and improve space weather prediction. International collaboration is a future goal for the project team.

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