Everything about the heavenly bodies defies human scale: their sizes, masses, and particularly their movements are in terms widely understood but hardly fathomable. That may explain why astronomic events have been predicted, observed and celebrated since the foundation of modern science: they can be truly once-in-a-lifetime events. Consider the transit of Venus, when the planet passes directly between earth and the sun, turning into a small speck on the glowing orb’s surface. The orbits of both bodies align them just twice, eight years apart, every 105-120 years. The last one of this generation was 2004; after 2012 there will not be another until 2117. We can consider ourselves lucky to be able to witness such a rare event, but those who got to see it in 1769 got an even rarer treat.

On this day, June 4, in 1769 the transit of Venus was followed up by a solar eclipse just hours later. Not only did the Earth and Venus align, but they were joined by the moon.

The cycle of earth-moon-and-Venus alignment can be measured in millenniums rather than centuries. Before 1769, the last time it happened was around 15,000 B.C., when primitive humans were first migrating across the frozen Bering strait into Alaska and North America. The next time it will happen will be 15, 232 A.D. (and who knows what that will look like.) But if you are impatient to wait that long, not to worry: there will be a solar eclipse during Mercury transit much earlier, in middle of the 6700s.