How Science Works #1…

In science, a hypothesis is a speculation that might explain a particular observation. This can then be tested to try and show that it is wrong. If it cannot be demonstrated to be wrong, if it explains the observed facts and if it allows accurate predictions to be made then it may be promoted to the level of theory. In science, a theory is the current best explanation for a series of observations and facts. Hence we have Atomic Theory, the Germ Theory of disease and the Theory of Evolution as some of the best available explanations for our observations of the natural world.

A scientific law describes a series of observations that have never been shown to contradict the law. The Law of Gravity accurately describes gravity, but does not provide an explanation as to why it happens. A good example of a law is Newton’s Laws of Motion. Briefly these are…

1. An object at rest will remain at rest unless acted on by an unbalanced force. An object in motion continues in motion with the same speed and in the same direction unless acted upon by an unbalanced force. This law is often called “the law of inertia”.
2. Acceleration is produced when a force acts on a mass. The greater the mass (of the object being accelerated) the greater the force needed (to accelerate the object).
3. For every action there is an equal and opposite reaction.

Newton’s Laws have predictive power; a beautiful example of which is the discovery of the planet Neptune.

Mercury, Venus, Mars, Jupiter and Saturn had been known about since ancient times because they can be seen, at certain times of the year, in the night sky. When the telescope came along it was possible to observe these bodies in greater detail. In 1781, William Herschel used his more powerful telescope to identify the seventh planet, Uranus. At some point in the 19^th century, mathematical calculations using Newton’s Laws of Motion disagreed with the observed orbit of Uranus. In 1846 a 24 year old English astronomer and mathematician, John Couch Adams predicted the existence of a planet beyond Uranus based upon the anomalies in the orbit of Uranus.

Adams did not publish his results but a French mathematician Urbain Jean Joseph Le Verrier did publish a prediction about where a new planet could be found. He based his calculations upon observations of the orbits of Jupiter, Saturn and Uranus. Using this prediction, astronomers Johann Gottfried Galle and Heinrich Louis d’Arrest pointed their telescopes at the appropriate region of space, and there was Neptune.

This is an example of why I find the work of scientists so remarkable. Phenomena are observed that seem to defy explanation but scientists do not settle for not understanding – they investigate. It is this willingness to explore that has, little by little, brought us to our current understanding of the natural world. This work continues to happen all around the world, and one day, you could also be contributing to the sum of human knowledge and understanding.

Questions…

1. What force is holding the planets in orbit about the Sun?
2. What value does this force have on Earth?
3. How does a planet differ from a moon?
4. How does a solar system differ from a galaxy?
5. How would you define a force?
6. Name any other forces, apart from that mentioned in Q1.
7. Which planet in the solar system has the most moons?
8. Name a planet in the solar system that has no moon.