Satellite calibrating using lunar irradiance measurement

Unlock the Secrets of the Moon: How Lunar Measurements are Changing Climate Science

Theo Raines in Climate & Environment June 2025 • 4 min read.

"Discover how cutting-edge lunar spectral irradiance measurements are revolutionizing climate data and paving the way for more accurate satellite calibrations."

For decades, the Sun and bright stars have been our go-to celestial benchmarks. Yet, Earth’s closest cosmic neighbor, the Moon, has lagged behind in terms of precise radiometric study. Previous lunar spectral irradiance scales have uncertainties between 5% and 10%. Such uncertainties limit the Moon's usefulness as a reliable calibration standard for climate science.

Driven by the need to ensure consistent climate data records despite gaps in satellite coverage, scientists have pioneered a new method to measure lunar spectral irradiance at visible wavelengths. This innovative approach promises to refine the Moon's role in climate monitoring, offering a stable, space-based reference point.

Recent advancements have yielded lunar spectral irradiance measurements with an uncertainty below 1% from 420 nm to 1000 nm. This leap in accuracy meets the stringent stability requirements of many climate data records derived from satellite imagery, opening the door to using the Moon as a calibration standard. This also offers the potential to bridge gaps in satellite coverage and validate atmospheric retrieval algorithms with unprecedented precision.

Why Lunar Spectral Irradiance Matters for Climate Data

Satellite calibrating using lunar irradiance measurement

Climate data records rely on the consistency of satellite images. Satellites monitor critical climate indicators, including vegetation, snow and ice albedo, clouds, and aerosols. The recent loss of key satellites and the delays in launching replacements highlight the urgent need to maintain data continuity. To truly understand climate variability and change, scientists must compare data across long time periods, bridging any gaps caused by satellite downtime.

The problem is, the absolute radiometric calibration of many satellite imagers at visible wavelengths isn’t accurate enough. Current calibration methods, which include solar diffusers and well-characterized sites on Earth, have limitations. Solar diffusers degrade over time, making it difficult to separate diffuser degradation from sensor degradation. Earth surface sites require constant maintenance to remain reliable, which isn’t always possible.

Calibration Standard: The moon may act as a universal calibration standard for Earth-orbiting satellites.
Atmospheric Independent: The moon is above the atmosphere, this avoids challenges associated with atmospheric correction.
Consistent Reference: As the moon is available to all Earth-orbiting satellites throughout their lifetimes it may allow for better comparison over time.

Lunar calibration bypasses these issues. The Moon is similar in brightness to Earth, eliminating the need for diffusers. As it's above the atmosphere, there’s no need for atmospheric correction. Plus, the Moon is available to all satellites orbiting Earth throughout their missions, creating a stable reference point over time.

The Future of Lunar Calibration

The improved measurement of lunar spectral irradiance marks a crucial step forward in climate science. With continued refinements and long-term measurement programs, lunar calibration promises to enhance the accuracy and consistency of climate data, bridging gaps in satellite coverage and validating atmospheric models. This paves the way for a more comprehensive understanding of Earth's changing climate and more informed environmental stewardship.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.6028/jres.118.020, Alternate LINK

Title: Precise Measurement Of Lunar Spectral Irradiance At Visible Wavelengths

Subject: General Engineering

Journal: Journal of Research of the National Institute of Standards and Technology

Publisher: National Institute of Standards and Technology (NIST)

Authors: C.E. Cramer, K.R. Lykke, J.T. Woodward, A.W. Smith

Published: 2013-10-01

Everything You Need To Know

Why is accurate measurement of lunar spectral irradiance important?

Accurate measurement of lunar spectral irradiance is crucial because it enables the development of a reliable calibration standard for Earth-orbiting satellites. Satellites are used to monitor climate indicators like vegetation, snow and ice albedo, clouds, and aerosols. Since the Moon is above the Earth's atmosphere, it can act as a consistent reference point, thus bypassing the limitations of existing calibration methods, such as solar diffusers, which degrade over time, and Earth surface sites, which require constant maintenance. This is very important for ensuring the consistency of climate data records despite gaps in satellite coverage and validating atmospheric models.

How does the Moon function as a calibration standard for satellites?

The Moon serves as a universal calibration standard because its spectral irradiance can be precisely measured and used to calibrate the instruments on Earth-orbiting satellites. Unlike solar diffusers, the Moon does not degrade over time, and unlike Earth-based sites, it doesn't require constant maintenance. Furthermore, being above the atmosphere, the Moon eliminates the need for atmospheric correction. The Moon's brightness is similar to that of Earth, which makes it a suitable reference for satellite instruments, allowing for long-term comparisons of climate data.

What are the advantages of using the Moon for satellite calibration compared to other methods?

Using the Moon for calibration offers several advantages over traditional methods. The Moon eliminates the need for solar diffusers, which degrade over time, and Earth surface sites, which require constant maintenance. The Moon is also above the atmosphere, avoiding the challenges of atmospheric correction. Furthermore, the Moon is available to all Earth-orbiting satellites throughout their missions, providing a stable reference point that allows for better comparison of data over time. This consistent reference is particularly important for bridging gaps in satellite coverage and validating atmospheric models with unprecedented precision.

How do recent advancements in measuring lunar spectral irradiance impact climate science?

Recent advancements have dramatically improved the accuracy of lunar spectral irradiance measurements, with uncertainties now below 1% from 420 nm to 1000 nm. This increased precision meets the stringent stability requirements of climate data records derived from satellite imagery. It opens the door to using the Moon as a reliable calibration standard. The advancement helps bridge gaps in satellite coverage, validates atmospheric retrieval algorithms and enhances the accuracy and consistency of climate data, ultimately leading to a more comprehensive understanding of Earth's changing climate.

What are the potential implications of improved lunar spectral irradiance measurements for our understanding of climate change?

Improved lunar spectral irradiance measurements hold significant implications for advancing our understanding of climate change. By providing a stable, reliable, and consistent calibration standard for satellite data, these measurements enable scientists to create more accurate and long-term climate data records. This allows researchers to better understand climate variability and change by comparing data over extended periods. The enhanced precision also helps in validating atmospheric models and bridging data gaps caused by satellite downtime or failures, ultimately contributing to more informed environmental stewardship and a deeper understanding of the Earth's changing climate. Moreover, increased accuracy improves the quality of climate models by providing more stable and reliable inputs for the processes they describe.