Alain Picard 
IN BRIEF Light spectra: Analysis of the light emitted by stars. Decomposition of white light via a prism or a grating. Absorption spectrum: Presence of dark lines, indicating chemical elements. Hydrogen: Identification by its specific emission lines. Visible colors: Observations ranging from violet to red. Emission lines: Allow identification of elements present in stars. Importance … Read more
IN BRIEF Giant gas planets: Jupiter and Saturn, formed nearly 5 billion years ago. Recent discovery of wandering double giant planets in the Orion nebula. Observation of planetary birth through gravitational collapse. Mysteries surrounding the formation and atmospheres of gas giants. Effects of atmospheric phenomena on Jupiter, including hurricanes and clouds. New theoretical models proposed … Read more
The evolution of planetary habitability represents a fundamental scientific quest, intertwining astronomy, geology, climatology, and biology. Since the discovery of the first exoplanets, researchers have been trying to understand how certain planets can support life, relying on Earth as the main model. The exploration of planetary systems, habitable zones around stars, and the study of … Read more
The quest for worlds suitable for life extends far beyond the traditional boundaries defined by the classic habitable zone. The study of extensive circumstellar habitable zones is revolutionizing our understanding of cosmic environments capable of supporting life. These zones correspond to orbital regions around stars where liquid water can exist and are now evaluated with … Read more
The cosmological entropy is at the heart of modern astrophysical research, promoting a deeper understanding of the growing disorder that structures the Universe. For over a century, this notion, intimately linked to the second law of thermodynamics, has prompted physicists to ponder the ultimate fate of the cosmos. Today, advances in quantum cosmology, particularly through … Read more
Modern cosmology is experiencing a fascinating epoch where the foundations of our understanding of the universe are constantly being questioned. At the heart of the debates are the alternative cosmological models, which propose different and sometimes radical views compared to the standard model based on the Big Bang theory. In 2025, the quest to decipher … Read more
Ultra-precise spatial photometry represents a major advancement in the precise study of light coming from celestial objects. This discipline, once limited to simple visual measurements, has transformed thanks to the integration of sophisticated space technologies and advanced optical instrumentation methods, offering an unprecedented ability to record the light variations of stars and other celestial objects. … Read more
In short, stellar occultations prove to be incredibly effective tools at the service of modern astronomy. By temporarily masking a star with a celestial body, they allow for obtaining exceptionally precise data on the size, shape, and the presence of atmospheres or rings around various objects in the solar system. They play a fundamental role … Read more
Since its launch in late 2013, the Gaia satellite, developed by the European Space Agency (ESA), has revolutionized stellar mapping by providing unprecedented instrumental precision in the measurement of position of stars. By meticulously scanning over a billion stars, Gaia enables the construction of an unprecedented catalogue that exponentially enhances our understanding of the structure … Read more
Very high energy gamma rays play a crucial role in understanding the most extreme and violent astrophysical phenomena in the Universe. This electromagnetic radiation, the most energetic known, is emitted by cosmic objects such as pulsars, supernova remnants, and relativistic jets. Recent studies conducted from observatories like HAWC or large ground-based telescopes now allow us … Read more