The ancient Greeks speculated about their Kosmos in terms recognisable as scientific today. Pre-Socratic thinker Thales believed water was the fundamental substance from which all else proceeded. Demokritus first proposed all matter was constucted of irreducably small particles called atoms. Today we know that the simplest expression of matter, the Hydrogen atom, is readily oxidised to form water, releasing a large dose of energy in the process. Hydrogen permeates the universe, in it’s preferred state as a hydrogen molecule, it is invisible to our telescopes and our other means of spectral detection.
Other Greek thinkers considered the motion of the heavenly bodies, planets, stars, comets and our Sun. The first to propose that the Earth moved round the Sun rather than believing in an Earth centred Kosmos was Aristarchus of Samos. Using geometrical mathematics, he calculated the relative sizes of the Sun and Moon, and reasoned that because the Sun was the biggest body in the Kosmos, and the only self luminous body, it must be at the centre of the part of the Greek Kosmos we now call the solar system.
But science makes many twists and turns on the path to knowledge, and the needs of navigators and astronomers for a quantifiable and predictive calculation system led to the adoption of the Earth centred system of Ptolemy, with it’s unphysical epicycles grafted into the theory to explain the apparent retrograde motion of planets at various times. This view was to dominate late classical and medieval thought for 1300 years due to the suppression of other ideas by the gatekeepers of knowledge. A theme we will be forced to return to later.
Eventually, Nikolaus Copernicus restored the Sun to it’s rightful place and his work was championed by Galileo Galilei, despite being placed under house arrest and having his telescope confiscated for a time by the guardians of orthodoxy. Galileo also methodically counted sunspots and we still use his observations as part of the sunspot record. Building on the work of Copernicus, Galileo, and Tycho Brahe, German born Johannes Kepler discovered that the proportions of the orbital distances and the rates of motion of the planets conformed to simple geometrical laws which revealed a harmony and resonance in the solar system as a whole.
Subsequently, Isaac Newton quantified the concept of gravity, and derived laws of motion describing relationships between mass, momentum and velocity which we still use today. Newton showed that the sun is engaged in continual motion around the centre of mass of the solar system (i.e. the barycentre or SSB) as a result of the gravitational force exerted by the planets, especially Jupiter and Saturn. He came to this conclusion analytically (not by observation) by working through the consequences of his law of gravitation. His cosmological theory of an isometric universe was superceded by Einstein‘s theory of General Relativity with its application to the concept of curved space-time.
“In 1801, the Astronomer Royal in Britain, Sir William Herschel, discussed the nature of sunspots, their variability, their effect on climate, and the position of the planets as possible causative forces. Although this work was published by the Royal Society, it was “ahead of its time”. Some century-and-a-half later, there was much more information, but not much more light.” -Rhodes Fairbridge-
The field of Solar Physics developed throughout the period, but the sun’s remoteness, and it’s enigmatic variation in activity made hypotheses of it’s nature difficult to validate until the recent development of sophisticated equipment and techniques to measure it’s magnetic field, surface activity and periodic parameters. The currently dominant Babcock-Leighton Dynamo theory of the way the sun generates it’s cyclic activity has seen little competition, despite its difficulties and lacunae.
2) Enter Paul José
In April 1965 Paul D. José, a scientist at the office of Aerospace Research at Holloway Air Force base in New Mexico published a short paper in The Astronomical Journal (vol.70 No.3) entitled: Sun’s motion and sunspots.
The paper included an intriguing diagram reproduced in part here:
The importance of the diagram and the rest of José’s paper will form the first part of the next installment.
To be continued…