and where they can attract or repel other magnets. Although we cannot see magnetic field lines, we can detect them using iron filings. The tiny pieces of iron line up in a magnetic field.

Many people will remember experiments in school with iron filings and bar magnets to unveil their magnetic field. It's not quite so easy to capture the magnetic field of the Milky Way though.

The solenoids serve double duty — first, they move pieces of flat “fridge magnet” material close enough to attract iron filings. Their second duty is of course provide a clock tick that will ...

Iron is magnetically soft – it can be easily magnetised and demagnetised. Magnetic fields lines are invisible but they fill the space around a magnet where the magnetic forces work on magnetic ...