Solar eclipses have always fascinated humanity. For scientists, they are more than just breathtaking celestial events—they offer rare windows into the mysteries of the Sun’s outer atmosphere. But these windows don’t open often. Total solar eclipses are fleeting, occur only once every 18 months or so, and can only be seen from narrow regions on Earth for just a few minutes. That’s where MESOM comes in.
MESOM, short for Moon-Enabled Sun Occultation Mission, is a bold new space mission concept that seeks to create an Artificial Solar Eclipse in space. Proposed by scientists from University College London, Aberystwyth University, and the Surrey Space Center, MESOM was unveiled at the Royal Astronomical Society’s National Astronomy Meeting (NAM 2025). If approved, it could provide solar scientists with a revolutionary new tool—turning the Moon into a natural instrument to block the Sun and reveal its secrets more frequently, and in greater detail, than ever before.
How MESOM Will Create Artificial Solar Eclipse in Space
At the heart of MESOM’s mission lies a clever orbital trick. A small satellite will be launched into a special orbit where it passes through the Moon’s shadow—specifically, its umbral cone—about once every 29.6 days, which is the length of a lunar synodic month. Each time it passes through the shadow’s apex, the satellite will experience a total eclipse of the Sun—in space.
These artificial eclipses won’t be limited to a few short minutes like they are on Earth. MESOM could observe eclipses for up to 48 minutes at a time, and over a two-year mission, it’s expected to witness around 80 eclipse-like events. Even more impressive, it will do this without interference from Earth’s atmosphere, resulting in clearer, more consistent data than any Earth-based observation could ever provide.
Seeing Closer to the Sun Than Ever Before
One of the main goals of MESOM is to observe the Sun’s inner corona—the intensely hot, but faint outer layer of the solar atmosphere. This region is crucial for understanding phenomena like solar flares, coronal mass ejections (CMEs), and space weather, all of which have the potential to impact Earth’s technology and satellites.
MESOM aims to observe the corona from a distance as close as 1.02 solar radii (about 710,000 kilometers from the Sun’s surface). That’s significantly closer than ESA’s Proba-3 mission, which can observe only from 1.1 solar radii. This extra 56,000 kilometers of proximity could make all the difference in unlocking the physics behind some of the Sun’s most energetic and least understood activity.
What MESOM Will Carry Onboard
MESOM isn’t just about clever orbits. It also comes equipped with a powerful suite of instruments designed to capture high-resolution images, analyze plasma composition, and decode the Sun’s magnetic field.
High-Resolution Coronal Imager
Developed with support from the U.S. Naval Research Laboratory, this imager will capture crystal-clear images of the Sun’s inner corona during each eclipse. These visuals will help map the fine-scale structure of solar flares and magnetic loops.
Coronal Mass Spectrometer (Artificial Solar Eclipse)
Built by Aberystwyth University and UCL’s Mullard Space Science Laboratory, this tool will analyze the composition of the corona’s plasma—shedding light on how particles are accelerated and how solar material interacts with magnetic forces.
Spectropolarimeter
Provided by the Spanish Space Solar Physics Consortium (S3PC), this instrument will measure the Sun’s magnetic fields and polarization of light—offering key data to study sunspots, flares, and the energy transfer in the corona.
Together, these instruments create an integrated observatory capable of gathering the kind of comprehensive data scientists can only dream of during a natural eclipse.
Solving the Coronal Heating Mystery
One of the greatest unanswered questions in solar physics is why the Sun’s outer atmosphere—the corona—is vastly hotter than its surface. While the solar surface sits at around 5,500°C, the corona can exceed a million degrees Celsius. This seems counterintuitive and has puzzled scientists for decades.
MESOM hopes to provide clues by observing this region over extended periods, repeatedly and with better resolution than any previous mission. With high-quality eclipse-like data collected every month, scientists can study coronal heating events, track particle movements, and monitor the birth of CMEs.
Understanding these processes isn’t just academically interesting—it’s practical. Space weather events like solar storms can cause real damage to power grids, satellites, and communication systems on Earth. A deeper understanding means better predictions and preparedness.
Building on Proba‑3’s Success
ESA’s Proba-3 mission, launched in 2024, was the first to use precision formation-flying of two spacecraft to simulate an artificial solar eclipse. It achieved remarkable engineering feats, creating a shadow large enough to block the Sun’s disk in space for hours at a time. However, Proba-3’s main objective was technological demonstration and observations of the outer corona.
MESOM takes that concept further by targeting the inner corona—and by using the Moon’s natural shadow instead of a second spacecraft. This not only cuts costs but enables a more stable and simpler configuration to focus entirely on the science.
Timeline and Mission Budget
MESOM was officially submitted for consideration under ESA’s F-class mission category in May 2025. F-class missions are designed to be fast, flexible, and affordable, with a cap of €205 million and a goal to launch within eight years of approval.
If MESOM is accepted, the mission could launch as soon as 2026–2028. That’s a rapid turnaround for a mission of such potential impact, underscoring the growing value of small satellite science missions in modern space exploration.
Educating and Inspiring the Public
Beyond its scientific value, MESOM has the power to captivate. Stunning eclipse images from space—longer, clearer, and more frequent than anything seen from Earth—could inspire the public in entirely new ways.
UCL solar physicist Lucie Green emphasized that MESOM’s visuals and discoveries could spark interest in science among younger generations, serving as a bridge between cutting-edge research and public imagination. The mission is expected to play a strong role in STEM outreach, bringing solar science to classrooms, media platforms, and museums around the world.
conclusion
MESOM represents a turning point in how we study the Sun. It’s innovative, efficient, and designed to answer the most critical questions in solar physics using natural celestial dynamics and cutting-edge instruments. By capturing eclipse-like conditions regularly and from space, scientists will be able to delve deeper into the workings of the solar corona, the origin of space weather, and the fundamental processes that affect our planetary neighborhood.
Whether it’s solving the mystery of coronal heating or helping to predict the next solar storm that could threaten Earth’s infrastructure, MESOM Artificial Solar Eclipse is poised to deliver data that could shape both science and society.
As we await a decision from ESA, one thing is clear: if MESOM flies, it will change how we see the Sun—not just occasionally, but every month, from above the clouds, in perfect clarity.
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