Thein front of the sun will occur Monday, a rare event that will not be seen again until 2032. Astronomers have been observing the celestial route for nearly four centuries now , but the first reliable observation, in 1631, was different than what scientists had hoped at the time, it was almost thrown away.
Observations on Mercury migration have been reported since the ninth century, but after Galileo introduced the telescope in 1610, it became clear that early viewers were more likely to see sunspots than Mercury.
For the move of November 7, 1631, a number of astronomers set out to capture Mercury's movement in front of our star. Only one, a Catholic priest in Paris named Pierre Gassendi, published his observations, indicating that he could not believe what he was seeing at the time.
"I am far from believing that Mercury's project will create a small shadow," Gassendi wrote.
The priest assumed the small area he saw was just a sunspot because he expected the Mercury disk to cover about ten o'clock in the sun, when in reality it would appear to be about one-hundred-feet in size. of our star.
"It is very surprising that early observers thought they were looking at Mercury during the day when they saw a sunspot and that it is now Gassendi, when he, in fact, observed Mercury during the day, thought he was looking for a sunspot, "Albert Van Helden wrote in 1976 for the Journal for the History of Astronomy.
Back in Gassendi's time, there were still many disagreements about the arrangement and size of the cosmos. This is the time when scientists argue whether the Earth revolves around the sun or vice versa. Interestingly, however, both camps more or less agreed with the estimated dimensions of the planets. And when it comes to Mercury, they are both wrong.
"Fortunately, he continued observing many hours and noticed that the small dark spot was moving faster across the face of the sun and along a peculiar path than a sunspot," wrote Todd Timberlake, author of Finding Our Place in the Solar System.
That persistence will pay off in the long run and will lead to some major corrections in our understanding of Mercury's orbit and the size of planets. Mercury's unexpected small size could also lead to a more accurate measurement of the distance between Earth and the sun. This, in turn, will give us a better idea of how vast the universe is.
All this understanding was almost delayed, though, when Mercury was temporarily written off as another place in the sun.