By Martin Redfern
BBC Radio science unit
Around the world, day and night, people are observing, recording, discovering. Many of them are not paid, professional scientists; they do it as a passion, even an obsession.
Uranus was discovered by amateur astronomers
These are citizen scientists, the subject of a short series of documentaries on BBC Radio 4.
A couple of centuries ago, most science was done by amateurs, often clergy or people of private means who were simply curious about the world around them.
They include now famous names such as the Rev Gilbert White who patiently recorded the natural history around his Hampshire village of Selbourne, and William Herschel and his sister Caroline who painstakingly scanned the night sky discovering, among other things, the planet Uranus.
Today, when almost every city has a university or research institute with departments funded and dedicated to science, you might imagine that the days of the amateur scientists are over.
Dave Tyler and colleagues with the BBC's Sue Nelson
Not a bit of it. Observations by volunteers are the basis for monitoring birds, plants, animals and insects worldwide, and highlighting the first signs of any that are endangered.
By night they study moths and bats or look out into the heavens to search for comets and exploding stars. Some do not even need to leave their homes, using their personal computers to process the massive amounts of data collected by professionals.
Over the years, as more and more is discovered, you might imagine that it would become harder for amateurs to break new ground. But technology has come to their rescue.
Today, many people have computers in their back bedrooms that are more powerful than those in top research institutes of 30 years ago. They can bring a level of sophistication to instruments such as telescopes that was unheard of only a few years ago.
Add to that the vast amounts of time and patience that enthusiasts are prepared to give and the citizen scientists become a powerful force in discovery.
Astronomy provides good examples. In New Zealand in 1946 the Rev Albert Jones spotted his first comet.
Dave Tyler's image of Saturn
He continued patiently to scan the sky on almost every clear night, making half a million observations of variable stars and several other discoveries; but it was not until the year 2001 at the age of 80 that he discovered his second comet.
As Brian Marsden, who for many years ran the centre in the USA where such discoveries are reported, puts it: "That's dedication!"
Veteran British comet hunter the late George Alcock discovered a total of five comets in his lifetime, by memorising the positions and brightnesses of 30,000 stars and regularly scanning the sky with binoculars looking for changes.
Canadian-born David Levy has been even more prolific. He has clocked up 23 comets including, with husband and wife team Eugene and Carolyn Shoemaker, comet Shoemaker Levy 9 which famously crashed into Jupiter in 1994.
That event brought home to many the awesome power of impacts and the risks we face here on Earth. As a result, professionals joined amateurs in their quest to spot more asteroids that might pose a risk.
Though asteroids are, for the most part, small, distant and almost invisible, amateurs can still sometimes measure them. With millions of stars in the sky, sooner or later asteroids pass in front of stars and blot their light out in an occultation.
By timing such occultations very accurately, John Harper at his observatory near Scarborough and other amateurs around the world are able to measure the size and even the shape of these asteroids.
Comet hunting is not only done through binoculars and telescopes in the middle of the night. The US/European satellite Soho has instruments pointed permanently towards the Sun, one of which is capable of spotting comets pulled close to our star.
The images are put straight onto the internet where dedicated amateurs such as Mike Oates in Manchester can analyse them before the professionals find time. By doing this he has now found 144 Sun-grazing comets in just a few years.
Many of them are short-lived, crashing into the Sun soon after discovery, but in each case, he was the first to spot it. Now the pair of "Stereo" satellites are due for launch, and they could provide even more images of these Sun-grazing comets ready for amateur analysis.
The work of comet hunters and asteroid spotters is impressive, but how about this for dedication: build up a catalogue of 12,000 galaxies, each one a star city of a billion Suns, and then scan them all every few days to see if a star has exploded!
Dave Tyler's image of Jupiter
That is what Tom Boles does from his observatory in Suffolk. On a clear night he will be using three big amateur telescopes simultaneously to record images of all the galaxies which he can later scan to spot the bright flare of an exploding star or supernova. He recently discovered his 204th.
Such work is not simply astronomical stamp collecting. When he is convinced that a discovery is genuine, he alerts the professionals so that they can turn their big telescopes on the galaxy and study the exact nature of the explosion.
From that, they are able to work out the distance of many of the galaxies and hence the rate at which the Universe is expanding. From such observations they have discovered that the expansion is accelerating, implying there is a dark energy at work in the Universe, representing more energy than all the visible stars and galaxies.
Without the work of dedicated amateurs, such discoveries would have been almost impossible.
Not all amateur astronomers are studying faint and distant objects in the Universe. Many, such as David Tyler in his back garden observatory near High Wycombe, simply glory in the stunning visual spectacle of the planets.
He uses little more than a sophisticated webcam on the back of his telescope to record video sequences of Saturn and Jupiter. The clever bit happens in his laptop computer which selects the clearest images and puts hundreds of them together to produce stunning photographs to rival the best on Earth.
Using such techniques, amateurs were the first to spot a new white spot on Saturn, a giant storm system that even the Nasa spacecraft Cassini, which is orbiting Saturn, had not noticed.
The contribution of citizen scientists to human knowledge is considerable, but for many of them it is simply the thrill of discovery and the beauty of the night sky that keeps them going out night after night.
As comet-hunter David Levy points out, the word "amateur" comes from the Latin to love. In that sense, he says, he and many other citizens scientists are true amateurs.
Listen again to BBC Radio 4' series on Citizen Science