The Roque de los Muchachos Observatory (ORM), part of the Observatorios de Canarias (OCAN) alongside the Observatorio del Teide (OT) on Tenerife, is one of the most important astronomical sites in the world. Together, these observatories host the telescopes and instruments of around 60 institutions from over 20 countries, forming the EU's largest

A few remarkable examples of alternative cosmological theories are shown, ranging from a compilation of variations on the Standard Model (inhomogeneous universe, Cold Big Bang, varying physical constants or gravity law, zero-active mass, Milne cosmology, cyclical models), through the more distant quasi-steady-state cosmology, plasma cosmology, or

Elemental composition guides the formation, evolution, and atmosphere processes of the lowest-mass stars and brown dwarfs, or ultracool dwarfs (UCDs). While the vast majority of known UCDs are solar-metallicity objects in the Milky Way's thin disk, a rare subsample of metal-poor stellar and substellar subdwarfs are known in the Solar Neighborhood