Astronomers and Time

Astronomers of the past few decades have above all been the authors of discoveries that have revolutionised our vision of the Universe. They have developed instruments and used them to observe the sky, measuring quantities that were accessible to them such as the temperature of a medium, the energy of particles, or the chemical composition of a gas. They have developed models which provide a consistent picture of these measurements, then used their models to predict new properties of the given objects, and so on and so forth. The whole of modern astrophysics is characterised by this way of doing things, which already goes back to ancient times. It is the essence of the scientific method, applied to observation of the sky.