The cosmos is full of strange and beautiful things. But compared to important things like the economy or even our everyday worries, isn't astronomy just an expensive entertainment?

That's not been true for most of history. From ancient times, study of the changing patterns in the sky told you when to plant and when to sow. Knowing the constellations told you about your place on the Earth's surface, so you could navigate the oceans. Civilisation relies on accurate time, so governments paid astronomers to synchronise timepieces to our only reliable clock: the motion of the stars.

Now we have atomic clocks and GPS - but GPS wouldn't work without understanding celestial orbits. Modern science, technology, and industry is a complex interacting whole, with astronomy a key part of the story. Newton may or may not have watched an apple falling from a tree, but we know that his theories of gravity and mechanics were driven by a desire to explain the motion of the Moon. Likewise, atomic physics was driven by the desire to understand the spectra of stars, and how the Sun burns. What will transform the world next? It’s hard to predict, but it's possible that when we finally understand dark matter and dark energy, this will have a practical impact on the world.

Astronomy has always pushed technologies needed to do our work. Key components of WiFi were developed by radio astronomers; our data compression techniques get used in medicine; and we were amongst the very first users of CCD cameras and the Internet. Space missions like the James Webb Space Telescope cost billions of dollars. Does that go to pay people like me? Certainly not! Nearly all of it goes back out in contracts to high-tech companies. We are very demanding customers who push them to innovate.

Last but not least, astronomy inspires and educates the next generation of scientists and technologists.

So the sky really matters – but we are in danger of losing it. As well as the light pollution that makes it almost impossible for ordinary people to see the stars, even big telescopes on remote mountaintops are increasingly plagued by satellites streaking across our images; the number is doubling every two years, and the mad space goldrush shows no signs of slowing down. Space is useful to everyday life - try living without satnav - but we may be shooting ourselves in the foot as the problem of space junk starts to run away.

As I write, a photographic exhibition, Our Fragile Space, is showing at the foot of the Mound as part of the Edinburgh Science Festival, and the photographer Max Alexander and myself will be picking up these issues at the Royal Society of Edinburgh’s free public event, Custodians of the Cosmos, on  April 3.

Professor Andy Lawrence is Regius Professor of Astronomy at the University of Edinburgh, author of Losing The Sky, and a Fellow of the Royal Society of Edinburgh. 

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