On the Radar

The pick of the science news

Equation exercise

Stretch your legs this day week to celebrate one of the most intellectual and revolutionary acts of graffiti in history, when Sir William Rowan Hamilton took a penknife and etched his freshly discovered quaternion equation into the stone under

Broom Bridge in Cabra in Dublin on a sunny October afternoon in 1843.

Next Thursday, October 16th, the annual Hamilton Walk will trace the Irish mathematician's footsteps from his home and workplace at Dunsink Observatory along the Royal Canal to the bridge where inspiration struck. Booking is essential, contact Dr Fiacre Ó Cairbre at NUI Maynooth, 01-7083763.

Picture the deepest fish in the sea

Scientists have captured video footage of surprisingly large swarms of fish at the deepest levels yet recorded, nearly five miles below the ocean's surface.

Researchers from the Universities of Tokyo and Aberdeen have plumbed the ferocious pressure of underwater trenches. This week they reported filming groups of snailfish at a depth of 7,700 metres in the north-west Pacific. "It's incredible. We thought the deepest fishes would be motionless, solitary, fragile individuals," said Prof Monty Priede, director of Oceanlab at Aberdeen University, instead they are sociable and active.

See www.oceanlab.abdn.ac.uk/

By numbers

1

The number of exercise sessions it takes to improve the body's fat-burning rate in obese people. A University of Michigan study found this in turn could help protect against type-2 diabetes.

200

The distance in kilometres at which the Nasa probe Messengerskirted past Mercury this week, generating new images of the planet's surface.