If you missed it, then too bad: at the very least you can learn why it was a big deal. #venustransit

by David Ng

First, for your calendar, you can note that the next one is in 2117.

(Via spaceweather.com).

Second, read this lovely piece by Amy Shira Teitel, as she tells you why it was such a big deal yesterday (and throughout history).

Here’s a bit to whet your appetite (and in doing so, illustrates what is arguably the first example of an international scientific collaboration):

“Halley died in 1742, 19 years before he could try his method on the 1761 transit. But a host of astronomers took up the challenge in his stead. European expeditions set out to India, the East Indies, Siberia, Norway, Newfoundland, and Madagascar to get the best and most spaced out views of the event. From the whole worldwide network, more than 120 transit observations were recorded, but most were of poor quality stemming from optical problems and inexperienced observers. For the 1769 transit, more than 150 observations were recorded from Canada, Norway, California, Russia, and famously Tahiti as part of Captain James Cook’s first expedition. But the results were only marginally better.

The state of technology in the 17th century made it impossible to record the exact moments of the start and end of the transit because of the so-called black drop effect. As Venus crossing in front of the Sun, a haze obscured the planet making it impossible for astronomers to make clear observations. But even poor results are results. In 1771, French astronomer Jérôme Lalande combined the observations from the 1761 and 1769 transits and calculated that 1 AU was 95 million miles (153 kilometers) give or take a half million or so miles. It was a start, but it wasn’t the precise value astronomers had hoped for.”