8/13/2023 0 Comments 1600s telescope drawingThe instruments may well be operated from consoles thousands of kilometres away, though there will be on-site technicians. They will also have adaptive optics to sharpen small field images and active optics to compensate for objective mirror distortion as the orientation of the telescope is changed. New observatories being equipped today can expect 8 – 10 metre diameter instruments with computer controlled positioning, image correction and digital image detection. Twenty-first century telescopes are as different from their nineteenth century predecessors as those were from 17th century versions. Of course we are still in the telescope age and this instrument is as important as ever in astronomy. That is only the first rung on a distance ladder whose length would not be well established for a further century and half. The nearest stars are over 250 thousand times as distant as the Sun, itself 150 million km away. Bessel began an answer by being the first to measure the distance to one of the nearest stars using the precision astrometric tools of the 1830s. Did the universe at large have structure? Just how far away are the stars in any case? Whatever the answers, they would be provided by evidence, not rhetoric. How did these fit into the scheme of things? Were they truly fuzzy objects like giant gas clouds or simply tight clusters of stars like a swarm of bees seen in the distance? Answering this question also drove the quest for ‘ more light’. Messier had charted about a hundred fuzzy objects in the late 18th century. So, was the universe infinite or in some way localised? Seeing more also meant seeing that not everything out there is a star. Did the supply of stars ever run out? Apparently not in the nineteenth century. ![]() The first detailed star charts were drawn up and double stars recognised, even though not at that time appreciated to be binary systems. The Moon was mapped in some detail, Mars seen to have polar caps, the great spot of Jupiter followed, Saturn found to have moons and rings, comets understood to be in the realm of planets, not the high atmosphere. Less than perfect was hugely better than nothing. ![]() Nonetheless, the genie was out of the bottle. As his life story showed, the old guard generally took their ideas to the grave.įor at least the first century of telescopic astronomy, the instruments themselves were optically imperfect and mechanically flimsy. Galileo’s evidence was a crushing blow for astronomy by assertion. Any understanding of what is out there must be based on evidence. He wasn’t talking about astronomy but simply emphasising that there is no escaping evidence. In the following century Robert Burns famously used the line: facts are chiels that winna ding. In the early 1600s, Galileo famously wrote about the myriad of stars fainter than naked eye vision could detect, about the Moons of Jupiter, sunspots and the changing phases of Venus. They allowed more precise models of the motions of the planets to be invented but they didn’t tell his contemporaries or immediate successors anything more about what planets or stars were.Įven the simplest telescopes made an immediate impact. The observations of the great astronomer Tycho Brahe were all taken before the invention of the telescope. Among the notable instruments were Arabic astrolabes, mural circles and variants of the quadrant and celestial globe. Some were finely made and allowed positional measurements to be recorded to better than one tenth of a degree. Yes, there were instruments before the telescope. Given the dire state of naked eye astronomy, the telescope deserves all the praise it is given.
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