Transit of Venus Black drop effect Conjunctions Commentary

Jeremiah Horrocks astronomy

Transit of Venus

• Jeremiah Horrocks proposed
• timing the transit of Venus
• across the face of the sun
• from different places on Earth
• to calculate our distance to the sun
• geometrically.
• Horrocks measured the transit of Venus in 1639
• and roughly estimated the distance to the sun,
• coming closer to the actual distance
• than anyone previously had.
• The next opportunities
• for making these measurements
• were long after Horrocks had died.
• Scientists coordinated their efforts
• and organized expeditions across the globe
• over the next two hundred years.

Black drop effect

• Optical effects
• bedevilled measurements.
• Turbulence of Earth’s atmosphere.
• Imperfections in the instruments.
• Darkening of the sun at its rim.
• The disk of Venus, sticking to the limb of the sun
• like a teardrop, made timing its entrance difficult.

Conjunctions

• Venus and Earth orbit the sun
• with different periods
• and at different inclinations.
• All these terms seem metaphorical;
• however, people are not planets
• orbiting alone in space.
• Transits of the sun are separated
• by hundreds of years.
• Alignments of people are separated
• by fears and stupidity,
• by habits and ignorance,
• and their irregular orbits rarely conjoin.