The 2026 Nobel Prize in Physics has gone to a telescope that points down, not up. On October 6, 2026, the Royal Swedish Academy of Sciences announced the prize for Francis Halzen, principal investigator of the IceCube Neutrino Observatory, recognising his decisive part in building IceCube and in discovering high-energy neutrinos that arrive from the cosmos ( IceCube announcement ). Imagine a detector made from a cubic kilometre of Antarctic glacier, built to catch a particle that can cross the Universe and pass through a planet without noticing. That sounds like science fiction. It is now a Nobel-winning instrument. Here is the story of how it happened, why it matters, and a well-earned round of applause for the people behind it. A bold idea: use the ice itself as the detector Neutrinos are among the most abundant particles in the Universe, yet they barely interact with matter. Trillions pass through your body every second without leaving a trace. That shyness is exactly...
A team of researchers from Denmark, Sweden and China has published a new study in Nature that reveals the composition and formation of the two most habitable planets in the Solar System: Earth and Mars.
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The study is based on the analysis of silicon isotopes, which are variations of the same element with different numbers of neutrons, in different types of meteorites. Silicon is the most abundant refractory element in rocky planets, and its isotopic composition can trace the origin and evolution of planetary building blocks.
The researchers found that Earth and Mars have distinct silicon isotopic signatures that differ from those of chondrites, which are primitive meteorites that represent the undifferentiated material of the early Solar System. This means that chondrites are not the main source of material for terrestrial planets, as previously thought.
Instead, the study suggests that Earth and Mars were formed from material similar to early-formed differentiated asteroids, which are meteorites that have undergone melting and segregation into a metallic core and a silicate mantle. These asteroids formed in the inner Solar System and had a lower silicon isotopic ratio than chondrites.
The study also shows that the silicon isotopic ratio of asteroidal bodies correlates with their accretion ages, reflecting the mixing of material from different regions of the Solar System over time. Mars, which formed earlier than Earth, avoided incorporating material from the outer Solar System, which had a higher silicon isotopic ratio. Earth, on the other hand, required about 26 per cent of material from the outer Solar System to match its silicon isotopic composition.
The study supports the idea that Earth and Mars formed rapidly by collisional growth and pebble accretion within three million years after the birth of the Solar System. Pebble accretion is a process in which small dust grains stick together to form larger bodies that can gravitationally attract more pebbles.
The study has important implications for understanding how terrestrial planets form and evolve in different environments. It also provides new constraints for future missions to explore the geology and geochemistry of Earth's neighboring planets.
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