Sunlight Destroys Asteroids Too Close to Sun
Researchers say intense solar radiation heats asteroid surfaces until material is blasted away, explaining why few near-Sun asteroids are observed.
Updated on Nov. 4, 2026 in Space
Mikael Granvik reported that sunlight destroys asteroids that come too close to the Sun, with most not surviving approaches inside about 0.2 astronomical units. Laboratory experiments presented at the American Astronomical Society's Division of Planetary Sciences meeting in Spokane, Washington, showed surface material explosively ejected under simulated near-Sun radiation.
Why it matters
Observed numbers of near-Sun asteroids are several times lower than calculated expectations, and the experiments offer a physical explanation for that gap. The findings help astronomers understand how asteroid populations are depleted and reshaped over time.
Asteroid 3200 Phaethon has a diameter of 5.8 kilometers and develops a comet-like tail at its closest approach to the Sun. In SHINES experiments, millimeter-size pieces of carbonaceous chondrite-like samples were ejected once the irradiated surface became hot enough, though the extraction does not say how these results scale to full-sized asteroids.
The players
Mikael Granvik
A planetary scientist affiliated with Luleå University of Technology in Sweden and the University of Helsinki in Finland, who studies asteroid orbital evolution and near-Sun asteroid destruction.
American Astronomical Society's Division of Planetary Sciences
A professional division of the American Astronomical Society that hosts meetings for researchers studying planets, moons, asteroids, and comets.
DESTINY+
A Japanese space mission scheduled for 2030 to study the rocky comet Phaethon.
The details
Granvik's SHINES experiment uses a vacuum chamber that concentrates the bright solar spectrum from a theater-style lamp onto a small surface, replicating intense near-Sun radiation. The experiments showed significant outgassing of volatile elements such as water and sulfur, and ejected fragments traveled at speeds large enough to escape the gravity of asteroids up to a kilometer across.
Timeline
December: Geminid meteor shower produced by asteroid 3200 Phaethon
January: Granvik reported explosive ejection results in Icarus
2016: Granvik and colleagues calculated near-Earth asteroid orbit evolution
Last week: Granvik presented results at the AAS Division of Planetary Sciences meeting in Spokane
2030: Japan's DESTINY+ mission to Phaethon is scheduled
The Big Picture
The SHINES results extend Granvik's earlier calculations of near-Earth asteroid orbit evolution from 2016 by providing a laboratory mechanism for asteroid loss. The findings challenge the assumption that calculated asteroid populations near the Sun are complete, pointing instead to surface destruction as a missing factor.
The findings could sharpen models of how asteroids are depleted and reshaped, informing future planetary defense and mission planning. Practical consequences for everyday life are not established by the extraction.
The takeaway
Asteroids that venture too close to the Sun can be stripped of material by sunlight itself, a process that helps explain why fewer near-Sun asteroids are observed than predicted.
What happens next
Japan's DESTINY+ mission to the rocky comet Phaethon is scheduled for 2030.
Further reading
For broader context on near-Sun objects, explore our Space coverage.
Source note: This article includes information reported by Sky & Telescope.
