How do We Know the Distance to the Moon? To the Planets?

Today in History, January 10, 1946:

ÔÇťOperation Diana”.

The US Army Signal Corps, using a “bedspring antenna” radar from a World War II era US Navy ship, somewhat modified, bounces a signal off of the moon, which took 2.5 seconds to return to the Earth.

The experiment was the precursor to using Radar to determine the distance to other bodies, such as Saturn, and for learning to communicate with later spacecraft outside of Earth’s atmosphere.

Diana was the Roman Moon Goddess, and this project would take the lead in naming later space projects after Roman Gods.

Crossing the Rubicon…The Die is Cast

Today in History, January 10, 49 BC:

Julius Caesar’s time was up as the General in charge of Cisalpine Gaul, a province of the Roman Republic encompassing current France, etc.

The Senate had ordered Caesar home to Rome…and by tradition, to leave his army behind; Armies were not allowed in the Republic proper, and for good reason.

As Caesar sat on the other side of the river Rubicon, with his army, he made a decision to cross. Once he did so he would become a criminal, committing an act of war. And there would be no turning back.

He made his decision and plunged Rome into a civil war. He would be named dictator for life when he was victorious, something that was as significant for Romans as it would be for us.

Hence, “crossing the Rubicon” and “the die is cast” are synonymous with making an irreversible decision.