The Transit of Venus

While I'm writing this the planet of Venus passes between the earth and the sun and can be seen as a dark speck against the sun's surface for those who have the right equipment. This astronomical phenomenon is called the transit of Venus and it occurs with a distinct regularity. The last time this happened was in 2004 and the next transit will be in 105 years' time. I am myself no astronomer and will refrain from going into details about the technical aspects, but I consider this a good excuse to commemorate one of the most important astronomers in the discipline's history.

In 1639 Jeremiah Horrocks (1618-41) discovered that despite what the planetary tables of Copernicus, Tycho Brahe and Johannes Kepler predicted there would be a transit of Venus on November 24 that year. Aside from proving the previous tables wrong the event showed that despite Tycho Brahe's postulation, the planets are not self-luminous objects. Despite his groundbreaking discoveries Horrocks was largely forgotten until the publication of two treatises in 1662. The transit of Venus was described in Venus in sole vista where Horrocks had jotted down a brief occasional poem. I will post it here in commemoration of Jeremiah Horrocks and his importance in the history of astronomy.

Thy return

Posterity shall witness; years must roll

Away, but then at length the splendid sight

Again shall greet our distant children's eyes.

Jeremiah Horrocks recording the transit of Venus, painted by J. W. Lavender in 1903