Magnetic microscopy image of a 1 mm by 2 cm by 1 cm slice of martian meteorite ALH84001, overlayed on top of a visual photo of the same slice. The colors give the field intensity, with red and yellow (blue) corresponding to upward (downward) magnetization. The fusion crust on the upper left side of the sample (visible as a thin black rind in the visual photograph) has been remagnetized in the Earth's field, while the interior of the meteorite retains the weaker, heterogeneous magnetism it acquired on Mars.

Designed by Francis Macdonald, Caltech