According to folklore, Newton’s theory of gravity was inspired by a falling apple, Kekule’s theory of chemical structure came to him in a dream about a snake, and Archimedes had his “eureka” moment in the bath. Profound science can often be revealed at unexpected moments. Yet few physicists would expect to learn anything by observing a humble garden gnome.

But they haven’t met Kern, a nine-inch, chip-proof figurine and the star of the world’s first mass-participation gravity experiment, which is exploring a little-known global phenomenon.

So far, Kern (named after the Kern and Sohn-manufactured precision scales with which he travels) has journeyed more than 20,000 miles across 15 countries, by plane, train, ship, bus and car. He has jetted into exotic locations such as Lima, Mumbai, Mexico, South Africa, San Francisco, Sydney and New Caledonia. He has even made it as far as the Amundsen-Scott South Pole Station.

And as Kern travels, his weight varies, due to a combination of the spin of the Earth and the fact that our planet is not round, but more potato- shaped, according to scientists.

“Most students - and teachers, for that matter - don’t realise that gravity’s effect changes from place to place,” says Tommy Fimpel of Kern and Sohn, one of the organisers of the experiment. “This means you will weigh slightly more or less depending on where you go. Our Gnome Experiment is a fun way to explain this.”

So far, the results are perfectly in line with scientific predictions. Kern was heaviest at the South Pole, tipping the scales at 309.82g. And he was lightest in Mexico, at a svelte 307.62g.

Scientists who take part in the experiment are sent a robust flight case containing Kern, his precision scales, and a pair of lab gloves and an airbrush so that he can be kept spotless - dirt could influence his weight. Once he has been weighed and has posed for a few shots for his blog, he is carefully returned to his case and shipped off to his next destination.

There are two main influences at work, according to Albert Sauter, managing director of Kern and Sohn. The first is the spin of the Earth. “If you are standing at the poles, you are basically spinning on the spot,” he says. “But if you are on the equator you are hurtling through space at a great speed, as though you are on one of those nausea-inducing rides at the fair.”

This rotation creates inertia. Or, in everyday terms, it pushes you away from the Earth, counteracting the force of gravity by up to 0.3 per cent - a very significant effect in scientific terms.

The other factor, which accounts for a further 0.2 per cent variance, is that the Earth is not a perfect sphere; it bulges slightly around the equator. So when you stand at the tropics, you are further away from the core of the Earth than if you stand at the pole, and you are less affected by the force of gravity.

Despite illustrating such weighty concepts, the experiment has succeeded in capturing the imagination of schoolchildren, the public and international media. Kern has appeared on several TV stations, including the Discovery Channel, as well as in national newspapers around the world. At peak, three people a minute were requesting to weigh the gnome, and many of these emails came from schools and laboratories. One woman went so far as to knit him a scarf for his trip to the South Pole.

As any celebrity will testify, such fame can open doors. Kern has visited CERN, the home of the Large Hadron Collider in Geneva, Switzerland, where they are attempting to answer science’s biggest questions by discovering the Higgs boson, the elusive “God particle” that endows mass to electrons and quarks. It was an apt location for an investigation into gravity.

Kern has even descended 2km underground into the world’s deepest laboratory, Snolab in Canada, where experiments are conducted into particle physics, dark matter and underground life. He weighed 0.1g less in the underground laboratory than above ground. This can be accounted for by the fact that he has less rock below him, hence less gravitational pull downwards. He also has more matter above, which exerts a slight gravitational pull upwards, according to Chris Jillings, the particle physicist who weighed him.

You might be wondering how scales can ever reliably measure anything if weight always changes depending on location. But precision scales are typically calibrated according to a globally accepted gravity standard, under strict laboratory conditions. For the purposes of this experiment, the scales were calibrated just once in the Kern and Sohn calibration laboratory. That way, any variances in the gnome’s weight would be an accurate reflection of local gravity differences.

“Before we get told off by the physics teachers, we realise that the Newton is the formal measure of weight, not the gram,” says Sauter. “But this experiment is about explaining gravity variances in a way everyone can enjoy and understand.”

Later this year, Kern is coming to the UK. The organisers will give a talk about the Gnome Experiment at the Natural History Museum in London. And there will be an official UK weigh-in under an important apple tree in Woolsthorpe Manor, Oxford - the very same tree that first inspired a young Isaac Newton.

You can follow Kern’s progress at www.gnomeexperiment.com, where you can fill out a form to request the one and only gnome kit. But please remember that Kern’s diary is rather full now he has achieved international stardom. He may take some time to arrive.

James Nester is a founder and coordinator of the Gnome Experiment. For more information email kerngnome@gmail.com or tweet @KernGnome

WHAT ELSE?

Key stage 1: Junior explorers

Take pupils on a virtual galactic tour and look at Earth from outer space in a lesson from mariyahali.

Key stage 2: Earth v Jupiter

Explore the difference between weight and mass in a planet-hopping BBC Class Clips video.

Key stage 3: Apple falling from a tree

Investigate Newton with MissAli87‘s colourful, differentiated presentation.

Key stage 4: Solar system top trumps

Explore the features of Earth’s planetary neighbours with Cressida- bowden’s game.

Key stage 5: Universal gravitation

Calculate Newton’s law with a thorough guide from the Institute of Physics.

IN THE FORUMS

Weight and mass are commonly confused. What misconceptions have you come across among your pupils? Share them in the science forums.

Find all links and resources at www.tes.co.ukresources032.