THE STARS

The origin of the chemical elements (the atoms of which the universe is composed) was finally revealed in detail by these three astronomers and one nuclear physicist in 1957. Left to right, Margaret Burbidge, Geoffrey Burbidge, Willie Fowler, and Fred Hoyle.




Gamow, von Weizsacker and Bethe (1937 - 39)
Hans Bethe (1906 - 2005)




Ray Davis (1914 - 2006), Nobel Prize 2002
John Bahcall (1934 - 2005)


The earliest neutrino telescopes used 37Cl nuclei, which captured neutrinos to yield 37Ar, or 71Ga nuclei, which captured neutrinos to yield 71Ge. It was soon realized that to get a suitably enormous detecting volume, you should just use very pure water, and look for the Cherenkov radiation due to neutrino-electron elastic scattering. (Antineutrinos can also be detected, by νe-bar + p → n + e+.) Interest in such studies was sparked tremendously in the 1970s when the early ongoing experiment by Davis detected only 1/3 the predicted number of solar neutrinos.  [Since it takes around 40,000 years for a photon to make its way from the sun's core to the surface, it was thought possible that the sun had gone out!]  The discrepancy was, of course, due to neutrino oscillations, which sparked interest even more.  Today, a large number of newer and larger neutrino telescopes are constantly being planned, constructed and put into service.  The large number of astrophysical sources of neutrinos (such as supernovae) make data from such telescopes extremely important in astrophysics.


Underwater neutrino telescopes:
Baikal (1993 on)
ANTARES (2006 on)
Super Kamiokande III (2006 on)
KM3NeT (future telescope; under construction since 2013)
NESTOR Project (under development since 1998)
TRIDENT (2030), at bottom of Pacific Ocean


Under-ice neutrino telescopes:
AMANDA (1996–2009, superseded by IceCube)
IceCube (2004 on)
DeepCore and PINGU, an existing extension and a proposed extension of IceCube.


Underground neutrino telescopes:
Sudbury Neutrino Observatory (closed 2006)
Soudan Lab, in Soudan, Minnesota
Sanford Underground Research Facility

The Antarctic Muon And Neutrino Detector Array (AMANDA), buried in the ice beneath the South Pole, ultimately became part of the IceCube observatory. IceCube, which was completed in 2010, consists of a cubic kilometer grid of sensors embedded below 4,900 feet (1,500 m) of ice. In Europe, researchers are developing plans for KM3NeT, which will span 1.2 cubic miles (five cubic kilometers) in the Mediterranean Sea. And physicists at the Baikal Neutrino Telescope in Russia's Lake Baikal, the largest freshwater lake by volume in the world, are planning to build the Gigaton Volume Detector (GVD), which would be one cubic km.

Summary of Neutrino Telescopes Worldwide






As of 2 October 2025, there are 6,022 confirmed exoplanets in 4,490 planetary systems, with 1,013 systems having more than one planet



Catalog of Exoplanets

The instability of multi-body gravitational systems arises from the inherent chaos and sensitivity to initial conditions in systems with three or more bodies, leading to orbits that can change drastically over time. While some systems, like our solar system, show stability over long periods due to a hierarchical structure (large mass differences and separated orbits), many others are not stable. Instability can manifest as gradual orbital changes from secular perturbations, dramatic chaotic scattering events, or the ejection of bodies over millions or billions of years. Causes of instability include:

• Many-body problem: Unlike a two-body system, which has a stable orbit, systems with three or more bodies are inherently chaotic and lack simple, predictable long-term solutions.

• Secular perturbations: The slow, cumulative effect of gravitational nudges between bodies can gradually change orbital elements like semi-major axis, eccentricity, and inclination over long timescales.

• Resonances: Orbital resonances, where the orbital periods of two bodies are in a simple ratio, can cause chaotic diffusion. When these resonances overlap, the system can become unstable.

• Lack of hierarchy: Systems without a clear hierarchical structure, where the masses are more similar and the distances are not well-separated, are particularly prone to instability and rapid changes.

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