Taking the Long View: The telescope

For my second post on the theme of “Taking the Long View”, I’m literally taking the long view.

Telescope: tele- +‎ -scope, from Latin telescopium, from Ancient Greek τηλεσκόπος (tēleskópos, “far-seeing”), from τῆλε (têle, “afar”) + σκοπέω (skopéō, “I look at”).

This is not a history of the telescope, merely a smattering of quite interesting factoids.

First, and Inevitably, answering “Galileo” to the question “Who invented the telescope?” would trigger the full QI klaxon and flashing lights. The first recorded telescopes appeared in the Netherlands in 1608. The first person to make a drawing of the moon through a telescope was English. Later in 1609, Galileo built his own telescopes, improving on existing designs, and published his findings. It is also quite interesting to consider how historical misconceptions arise. Being the first to publish and nearly being burnt at the stake for it probably helped Galileo get ahead.

A demonstration of the telescope by Galileo at a reception in 1611 prompted the coining of the word, but by whom? Was it the Greek mathematician Giovanni Demisiani, or Prince Frederick Sesi?

How do you measure the distance from the earth to the sun? In 1716 Edmund Halley (he of the comet) illustrated that it could be calculated by timing the transit of Venus across the sun’s face, which led to Captain James Cook’s first voyage around the world in 1769.

Cook himself was one of the astronomers on board Endeavour. The other was Charles Green, and they trained others on board as observers. The voyage to Tahiti took about eight months, about as long as it would take modern astronauts to reach Mars. They set up three portable observatories on the islands of Tahiti and Moorea, with instruments supplied by the Royal Society and Royal Observatory. The telescopes included Gregorian reflectors fitted with micrometers. Isaac Newton may have been the first to build a reflecting telescope in 1668, but not the first to design one. That was Scottish mathematician James Gregory five years earlier.

The weather smiled on Cook, Green et al, although their observations were sabotaged by the “black drop effect”. Neverthless, the observations taken on 3 June 1769 gave the distance from the earth to the sun as 93,726,900 miles, about 0.8% out. Not bad!

Both this and the earlier unsuccessful attempt in 1761 were international endeavours, with observations taken across the globe. Even though Britain and France were at war or in competition, each granted safe passage to the other’s astronomers. But Cook had other sealed orders to open after the transit – to seek and claim Terra Australis Incognita. This led to the charting of New Zealand and eastern Australia, including Botany Bay.

At the Battle of Copenhagen in 1801, Nelson received an order transmitted by signal flag to withdraw his ships. Except he didn’t receive it, but lifted his telescope to his blind eye and said “I really do not see the signal”, thereby coining the phrase ‘to turn a blind eye’. Cursory googling reveals no extra details about the telescope.

Nowadays, telescopes are big enough to have names. But imagination has not kept up with gigantism. The Very Large Telescope, or VLT, is an array of four 8.2m reflecting telescopes in the Atacama desert in Chile. The Southern African Large Telescope, or SALT (kudos for the acronym), is in South Africa, in the Karoo. And the Very Large Array, or VLA, is a radio telescope in New Mexico.

Jocelyn Bell spent two years of her PhD building a radio telescope in a field, in theory to study quasars, but in practice to discover pulsars in 1967… for which she didn’t receive the Nobel Prize. Today, the rather more splendid sounding Interplanetary Scintillation Array looks as though it could be used to grow hops.

The Hubble Space Telescope was launched in 1990, and is still in operation. It has taken some remarkable pictures, including this HD panoramic view of the Andromeda Galaxy (see also video below), and done some science too. Apparently, anyone can apply for time on the telescope, including 13 amateur astronomers between 1990-97. Here’s how.

Finally, there will be a solar eclipse on 20th March. Don’t point a telescope directly at the sun. Enjoy!