Celestial mechanics is a branch of mathematics and astronomy that deals with the motions of celestial objects. The field applies principles of physics, gravitation, historically classical mechanics, to astronomical objects such as stars and planets to produce ephemeris data. Orbital mechanics (astrodynamics) is a subfield which focuses on the orbits of artificial satellites. Lunar theory is another subfield focusing on the orbit of the Moon.
For our latest developments/activities in this area, please see the listing at the end of this article.
Modern analytic celestial mechanics started over 300 years ago with Isaac Newton's Principia of 1687. The name "celestial mechanics" is more recent than that. Newton wrote that the field should be called "rational mechanics." The term "dynamics" came in a little later with Gottfried Leibniz, and over a century after Newton, Pierre-Simon Laplace introduced the term "celestial mechanics." Prior to Kepler there was little connection between exact, quantitative prediction of planetary positions, using geometrical or arithmetical techniques, and contemporary discussions of the physical causes of the planets' motion.
The gravity force acting over eons has provided the solar system with an intricate dynamical structure, much of it revealed by recent space missions. Mathematical tools and physical models are needed for a complete understanding of the subject.
This is a multi-disciplinary subject that combines expertises from Geophysics, Dynamical Systems, and Numerical Simulations. We study the geophysical effects that modify the spin and the orbits of planets and satellites, in particular tidal effects and core-mantle friction.
See here a movie made by the NASA Science "Understanding orbits and Kepler's laws", for a brief historical review on the dynamics of the solar system.
Three Gr@v members appear in the 2024 updated science-wide author databases of standardized citation indicators, commonly known as the Stanford University ranking of top 2% scientists in the world. The top 100 scientists in Portugal, from the same raking, features one CIDMA and Gr@v researcher.
The stimulating "Black Holes Inside and Out" meeting took place in Copenhagen, Denmark, in August 2024. C. Herdeiro was one of the invited speakers. More info here.
The 11th School on Astrophysics and Gravitation will take place at Instituto Superior Técnico in Lisbon, from 1-6 September 2023. C. Herdeiro and M. Zilhão are two of the lecturers. More info here.
The next decade will see an overwhelming number of cosmological surveys coming online. The Square Kilometre Array Observatory (SKAO) will, among several other science cases, map the distribution of cold neutral Hydrogen in the Universe using its spin-flip transition emission line at rest of 21cm or 1.4GHz and a novel technique called Intensity Mapping (IM).
Our group visited Colégio de Lamas, in Santa Maria da Feira, to explain basic concepts about Earth and Space. Inevitably, the questions end up discussing black holes!