Crop circles are one of the planet's great mysteries, and nowhere are they more of a puzzle than in southern England.
The South has more crop circles than almost any other part of England.
For years people many thought they were the creation of alien visitors from space.
Others claimed that mysterious forces or unknown energies were at work.
Sceptics believed that they were entirely man-made.
So what should we make of these mysterious markings?
Where do they come from?
Crop circles are unexplained designs that appear, usually overnight, often in fields of wheat and corn.
Everyone seems to have their own theory of crop circle formation. Here's the main theories from leading crop circle expert Brian Hussey.
Whirlwind or plasma vortex
A vortex forms high above the ground and then breaks to ground level like a tornado. One of the earliest theories.
Plasma gravitational theory
A directed plasma often accompanied by light phenomena.
Earth energies
Caused by geomagnetic activity. Ley lines act as a vital current flowing through the earth.
Extra terrestrial origin
Crop circles are landing craft or navigation markers for super intelligent aliens from outer space.
Underground archaeological
Crop circles are caused by a form of underground energy. Symbolic crop circles often appear close to sacred sites.
Chemical
No longer viewed as realistic.
Hoaxes
Crop circles are man made constructions.
God Force
Circles are created by some Godly act.
Military experimentation
Caused by top secret military experiments.
Whatever the theory, crop circles will continue to baffle us. Beautiful, inexplicable, mathematical and magnificent, crop circles remain one of the modern wonders of the world.
Some experts like Lucy Pringle even proclaim their healing powers. She claims that a crop circle cured her long standing tennis injury.
Top of the crops
The recent Hollywood film "Signs" has renewed interest in the crop circles.
Mystical crop circles in the movie Signs
In the movie, Mel Gibson plays a farmer whose life is turned upside down when a crop circle suddenly appears in his field.
M. Night Shyamalan's supernatural film has whetted the public's appetite for more information about the meaning of crop circles.
In the film, the art department created a large 100 feet wide crop circle.
To do this they took a 50 foot line, placed it in the centre of the field, stood on a ladder, and then, with a line tied to a pole, walked in a circle to create its radius.
One man led the rest of the crew, pushing down the corn with planks three of four stalks at a time.
It took them several hours to create the crop circle.
Creating a crop circle
Circle makers and hoaxers are said to be responsible for up to 80% of crop circles.
The main crop circle season runs from May through to early September.
Top of the crops - a crop circle in the south of England
Crop circles are so popular that there's been an explosion of activity from crop circle makers especially in south and south west England.
Recently the band The Levellers asked crop circle experts, Circlemakers, to create their logo as a crop circle for their pop video.
Circlemakers also made a crop circle for the cereal company Weetabix as part of an advertisement.
So how do crop makers go about making their crop circles?
By following a few basic rules, the circle makers can find themselves 'top of the crops', creating the season's most jaw-dropping and mysterious crop circle formation.
Making a crop circle
We've pieced together the techniques used by the world's leading crop circle makers.
1. The makers select a field. They often use dowsing rods to check earth energies. Ideally they should ask the owner for permission. Often they don't and they trespass on property.
2. The makers draw a crop circle on paper or design it on a computer.
3. The circle makers get together vital equipment and a team of three people. They usually wait until dusk or darkness.
4. The circle makers identify the centre of the circle. They take a length of tape and create the main circle. One person holds the end of the tape. The second person holds the other end and walks around, creating a human compass. The third person follows behind, stomping on the ground.
5. Having completed the main circle, they make an inner circle using slightly less tape.
6. On the inner circle, they make a series of marks.
7. Once complete, they mark out two equal points along the diameter of the inner circle. Then they stomp straight lines from these to each of the marker points.
There's dozens of different crop circle formations including crescents, rings, arcs, diamond shapes, spirals, knots and concentric circles.
Show me a sign!
The Circlemakers see crop circle formation as an art, and boast a special section on creating circles on their web site.
There are also dozens of groups who deliberately create hoax crop circles undercover.
However, some farmers are less than enthusiastic, and many see the act of illegal crop circle creation as trespass and vandalism.
A word of warning ..
Don't forget that trespass and destruction of a farmer's fields is illegal and costly.
If you're thinking of creating circles illegally, think twice. Why not study the brilliant examples of existing crop circles on your computer at home instead!