Prehistory In the French Maritime Alps, in the Vallée des Merveilles (about 100 km [60 miles] north of Nice), are thousands of petroglyphs dating from the Bronze Age (c. 2900–1800 BCE). The culture left images of the objects that concerned it—horned animals, the weapons used to hunt them, and…
Astronomy was the first natural science to reach a high level of sophistication and predictive ability, which it achieved already in the second half of the 1st millennium BCE. The early quantitative success of astronomy, compared with other natural sciences such as physics, chemistry, biology, and meteorology (which…
No area of science is totally self-contained. Discoveries in one area find applications in others, often unpredictably. Various notable examples of this involve astronomical studies. Isaac Newton’s laws of motion and gravity (see also celestial mechanics: Newton’s laws of motion) emerged from the analysis of…
Theory is just as important as observation in astronomy. It is required for the interpretation of observational data; for the construction of models of celestial objects and physical processes, their properties, and their changes over time; and for guiding further observations. Theoretical astrophysics is based…
As a departure from the traditional astronomical approach of remote observing, certain more recent lines of research involve the analysis of actual samples under laboratory conditions. These include studies of meteorites, rock samples returned from the Moon, cometary and asteroid dust samples returned by space probes,…
Most of what is known about the universe comes from observations of electromagnetic radiation. However, there are other “cosmic messengers.” Gravity waves are disturbances in space-time that can be detected by very large laser interferometers. Gravity waves and gamma-ray bursts have been observed from neutron-star mergers. Neutrinos and cosmic rays are other particles that can,…
Although the human eye remains an important astronomical tool, detectors capable of greater sensitivity and more rapid response are needed to observe at visible wavelengths and, especially, to extend observations beyond that region of the electromagnetic spectrum. Photography was an essential tool from…
Before Galileo Galilei’s use of telescopes for astronomy in 1609, all observations were made by naked eye, with corresponding limits on the faintness and degree of detail that could be seen. Since that time, telescopes have become central to astronomy. Having apertures much larger than…
Astronomical observations involve a sequence of stages, each of which may impose constraints on the type of information attainable. Radiant energy is collected with telescopes and brought to a focus on a detector, which is calibrated so that its sensitivity and spectral response are known. Accurate…
Cosmology is the scientific study of the universe as a unified whole, from its earliest moments through its evolution to its ultimate fate. The currently accepted cosmological model is the big bang. In this picture, the expansion of the universe started in an intense…