Saturday Night Science: Losing the Nobel Prize

“Losing the Nobel Prize” by Brian KeatingEver since the time of Galileo, the history of astronomy has been punctuated by a series of “great debates”—disputes between competing theories of the organisation of the universe which observation and experiment using available technology are not yet able to resolve one way or another. In Galileo’s time, the great debate was between the Ptolemaic model, which placed the Earth at the centre of the solar system (and universe) and the competing Copernican model which had the planets all revolving around the Sun. Both models worked about as well in predicting astronomical phenomena such as eclipses and the motion of planets, and no observation made so far had been able to distinguish them.

Then, in 1610, Galileo turned his primitive telescope to the sky and observed the bright planets Venus and Jupiter. He found Venus to exhibit phases, just like the Moon, which changed over time. This would not happen in the Ptolemaic system, but is precisely what would be expected in the Copernican model—where Venus circled the Sun in an orbit inside that of Earth. Turning to Jupiter, he found it to be surrounded by four bright satellites (now called the Galilean moons) which orbited the giant planet. This further falsified Ptolemy’s model, in which the Earth was the sole source of attraction around which all celestial bodies revolved. Since anybody could build their own telescope and confirm these observations, this effectively resolved the first great debate in favour of the Copernican heliocentric model, although some hold-outs in positions of authority resisted its dethroning of the Earth as the centre of the universe.... [Read More]


Total Lunar Eclipse: Now that’s a dark one!

On the night of July 27, 2017 (as reckoned in Universal Time, as we use at, the longest total lunar eclipse of the 21st century occurred.  As I am writing this, the total eclipse is just about to end.  The eclipse is not visible in the Western Hemisphere.

Total lunar eclipse: 2018-07-27, mid-eclipse... [Read More]


March Equinox 2018

Equinox: 2018-03-20 16:15 UTCThe March equinox occurs this year at 16:15 UTC on March 20.  This is the moment when the subsolar point crosses the equator headed north.  The line of day and night as seen on a map as above (produced by Earth and Moon Viewer using NASA imagery with snow and ice cover representative of March) is vertical, indicating that day and night are of equal duration everywhere on Earth.  The terminator (day/night line, not killer robots from the future) appears to curve near the poles because of the projection of the spherical Earth onto a flat map.  Here is a view of the Earth above the terminator at the moment of equinox.

Terminator at equinox: 2018-03-20 16:15 UTC... [Read More]


TOTD 2018-01-10: Natural Philosophy, Then and Now

William Herschel (1738–1822) wrote:

In this great celestial creation, the catastrophy of a world, such as ours, or even the total dissolution of a system of worlds, may possibly be no more to the great Author of Nature, than the most common accident in life with us, and in all probability such final and general Doomsdays may be as frequent there, even as Birthdays or mortality with us upon the earth. This idea has something so cheerful in it, that I know I can never look upon the stars without wondering why the whole world does not become astronomers; and that men endowed with sense and reason should neglect a science they are naturally so much interested in, and so capable of enlarging their understanding, as next to a demonstration must convince them of their immortality, and reconcile them to all those little difficulties incident to human nature, without the least anxiety.... [Read More]