The timing is appropriate. It is a little over two weeks since Venus slid across the sun and gave tantalising evidence of solar system physics for just the sixth transit since Jeremiah Horrocks saw a black dot creeping over a paper circle in a village called Much Hoole, not far from Liverpool.
Roger Horrocks, emeritus professor of Auckland University's department of film, television and media studies, has long been fascinated by the English astronomer.
As a teenager he, too, was captivated by the night sky and thrilled to learn that a crater on the moon bore his surname. He liked to imagine he was related to Jeremiah.
"He was such a whiz-kid. He was self-educated, a teenager at the time he predicted the transit of Venus and he's described as the father of British astronomy.
"I wanted to know more about him. He was a Horrocks. He came from the same area of England as my father [Bolton in Lancashire].
"He was a hell of an interesting teenager who came from a pretty backward part of the country and yet he made these big discoveries."
From Jeremiah Horrocks, working in the 17th century, the world learned that the moon followed an elliptical path around the earth and he had a stab at calculating the distance between the earth and the sun.
For the 21st century Horrocks, the elements of the documentary were coming together. Funding came from two high-level scientific establishments, the Allan Wilson Centre and the MacDiarmid Institute, and the late Sir Paul Callaghan weighed in with enthusiasm.
Sir Paul, a physicist who placed great store in the power of science as an economic force, was behind an enterprise that spun a web of science-related projects off this year's transit. He did not hesitate to embrace the Horrocks' vision.
Recalled Roger Horrocks: "He was intrigued by the Jeremiah connection. He saw it as a human element in a science documentary."
The personal history, says Roger Horrocks, was wrapped up in their search for the Jeremiah connection.
But the bigger story involved the history of the human family and its New Zealand branch, which in turn folds into pioneering work by Allan Wilson Centre scientists. Wilson was a stellar New Zealand scientist who used novel methods involving DNA to answer fundamental questions about evolutionary biology.
Tolaga Bay, which Cook encountered nearly 250 years ago and where Sir Paul's transit celebration played out this month, offered the filmmakers a location to delve into more profound subject matter given its central place in New Zealand's settlement history.
Naturally, the Horrocks also carted their gear to Lancashire. They found people who shared their surname and could trace their family back 500 years. They filled gaps in Jeremiah's story, gaining a sense of what inspired a young man to understand his world. They even found a place called Horrocks Fold, where wonderfully preserved homes date from the 1600s.
And what of the link to Jeremiah? Are the NZ Horrocks related to the curious young man who made delicate instruments, discovered errors in the work of the great astronomer Johannes Kepler, wrote poems that captured his wonder and excitement and is honoured by a plaque in Westminster Abbey, across the aisle from the great physicist Sir Isaac Newton?
Without giving too many secrets away (the film is not due for release until later this year), the Horrocks say he and Dylan share a close DNA match with a line of English Horrockses who could trace their line back to the early 1600s and had links to Jeremiah's uncles or cousins. Jeremiah died young, had no siblings and was unmarried.
Results of more DNA work are awaited, with the outcome of further genealogical inquiries.
"We're in with a chance," says Horrocks. The answer, like all good mysteries, will be revealed when the film gets to screen.
Jeremiah Horrocks
* 1618- 1641.
* Made the first observations of a transit of Venus and proved the moon's orbit is an ellipse. Died young, but his achievements earned him the title of father of British astronomy.
* What he said on observing the transit: "I beheld a most agreeable spectacle."
* What others said: "What an incalculable loss." - His colleague William Crabtre
