Abstract
The total solar eclipse of August 21, 2017, gave the high-altitude ballooning community an exceptional opportunity to study lighting conditions in the stratosphere during a total solar eclipse across multiple portions of the spectrum. Sensors on balloon platforms flown in Oregon and Nebraska measured changes in the sky’s overhead intensity at wavelengths ranging from 940 nm (Infrared A, also know as near infrared (NIR)) to 280 nm (Ultraviolet B, also called UVB) during partial eclipse and totality. The moon’s shadow was imaged in near infrared and the Earth’s horizon was imaged in thermal infrared, also known as far infrared (FIR).
Intensity measurements at various wavelengths were made using Neulog Light, UVA, and UVB modules, as well using as a LED-based photometer (a Forest Mims design) to study the intensity of eight colors spanning the spectrum from 940 nm infrared to the violet/ultraviolet boundary (400 nm). A Mobius ActionCam was modified for recording NIR, while blocking visible light. A microcontroller/servo combination was use to trigger a Seek Reveal thermal camera for the horizon experiment.
Preliminary analysis suggests that the sky’s overhead intensity shows no apparent effect based on wavelength – a somewhat unexpected result. Swinging of the photometer suggests that future measurements should incorporate a sun sensor. The NIR images of the Moon’s shadow are very clear – NIR light is more effective at penetrating the haze of the atmosphere than visible light. There is no evidence in the thermal imager of the eclipse shadow affecting the surface temperature of the Earth.
Studying a Total Solar Eclipse in Multiple Wavelengths from a Near-Space Platform
The total solar eclipse of August 21, 2017, gave the high-altitude ballooning community an exceptional opportunity to study lighting conditions in the stratosphere during a total solar eclipse across multiple portions of the spectrum. Sensors on balloon platforms flown in Oregon and Nebraska measured changes in the sky’s overhead intensity at wavelengths ranging from 940 nm (Infrared A, also know as near infrared (NIR)) to 280 nm (Ultraviolet B, also called UVB) during partial eclipse and totality. The moon’s shadow was imaged in near infrared and the Earth’s horizon was imaged in thermal infrared, also known as far infrared (FIR).
Intensity measurements at various wavelengths were made using Neulog Light, UVA, and UVB modules, as well using as a LED-based photometer (a Forest Mims design) to study the intensity of eight colors spanning the spectrum from 940 nm infrared to the violet/ultraviolet boundary (400 nm). A Mobius ActionCam was modified for recording NIR, while blocking visible light. A microcontroller/servo combination was use to trigger a Seek Reveal thermal camera for the horizon experiment.
Preliminary analysis suggests that the sky’s overhead intensity shows no apparent effect based on wavelength – a somewhat unexpected result. Swinging of the photometer suggests that future measurements should incorporate a sun sensor. The NIR images of the Moon’s shadow are very clear – NIR light is more effective at penetrating the haze of the atmosphere than visible light. There is no evidence in the thermal imager of the eclipse shadow affecting the surface temperature of the Earth.