News and opinions from Glenn Elert

On 30 June 1970, Cosmonauts Alexei Leonov, Valeri Kubasov, and Pyotr Kolodin died of asphyxiation as their Soyuz 11 spacecraft was preparing to re-enter earth’s atmosphere. A ventilation valve was jostled into the open position when the descent module separated from the service module. The cabin depressurized rapidly and the crew was dead in less than a minute.

A meteor or comet fragment exploded in the atmosphere near the Tunguska River in Siberia. The energy released was about 1000 times greater than the nuclear blast at Hiroshima, Japan.

Io Galileo Galilei figlio del q. Vincenzo Galilei da Fiorenza, dell’età mia d’anti 70… dovessi lasciare la falsa opinione, che il sole sia centro del mondo, et immobile, e che la terra non sia centro, e che si muova; e che non potessi tenere, difendere, ne insegnare in qualsi voglia modo, nè in voce, né in scritto la detta falsa dottrina….		I, Galileo, son of the late Vincenzio Galilei of Florence, seventy years of age… abandon the false opinion that the Sun was the centre of the universe and immoveable, and that the Earth was not the centre of the same and that it moved, and that I was neither to hold, defend, nor teach in any manner whatever, either orally or in writing, the said false doctrine….
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Lunokhod 2 was the second robotic rover to land on the moon. It operated from January to June 1973 in the Sea of Serenity (Mare Serenitatis). Because it has a retroreflector array mounted on it, it’s location can be determined with sub-meter precision. Lunokhod 2 was sold by the Lavochkin Association to computer game entrepreneur Richard Garriott for $68,500 in 1993.

Surveyor 1 was the first lunar lander of the US space program. It lies in the Sea of Storms (Oceanus Procellarum).

The Greek philosopher Thales of Miletus (Θαλής ο Μιλήσιος) predicted the occurrence of an eclipse on this day in 585 BC. The eclipse occurred during the Battle of Halys (also known as the Battle of the Eclipse) between a Greek tribe (the Lydians) and a Persian tribe (the Medes). The sight of the sun disappearing brought the battle to a halt and the warring factions made peace immediately.

Thales’ prediction probably played no role whatsoever in the political events of this day. The armies stopped fighting because they thought the eclipse was an omen of bad fortune. They believed the eclipse was supernatural. Thales thought exactly the opposite. He is generally credited with saying something like “every observable effect has a physical cause”.

An eclipse occurs whenever the moon passes between the sun and the earth in such a way that the moon is able to cast a shadow on the earth. The period between such events is roughly 18 years and is known as the Saros cycle. Thales may have known about this cycle or he may have made observations of the moon a few days before the eclipse and projected its path across the face of the sun. I don’t know if anyone knows the answer to this part of the story. What we do know is that Thales did not consult an oracle, or divine the answer by looking at the entrails of a goat, or receive a message from Zeus. He saw the eclipse as a natural event dictated by natural laws and made a testable prediction based on observations. (NASA has a great website that both predicts and retrodicts eclipses.)

Thales of Miletus was the earliest known person to think scientifically. In essence, he was the first scientist. His prediction of the eclipse is the earliest recorded example of hypothesis testing. In essence, it was the first scientific event. This makes 28 May 585 BC the day on which science was born.

Mikołaj Kopernik, usually known by his latinized name Nicolaus Copernicus, was the first astronomer to formally develop a heliocentric model of the solar system. The final version of his theory was published on the day of his death, 24 May 1543, under the title De Revolutionibus Orbium Cœlestium (On the Revolutions of the Celestial Spheres). The most famous line from this book is …

In medio uero omnium residet Sol. (In the center of all rests the Sun.)