Two coils of wire are wound around an iron core.

It probably has an iron core, and an atmosphere that's mostly oxygen.

By contrast, Earth's iron core is about 30 percent of the planet's mass.

That's not enough to produce a set of swirls despite its liquid iron core.

It's filled with a dense iron core and so it gives off a magnetic field.

The Moon is similar, but has a much smaller iron core.

Finally, a larger planet is likely to have a large iron core.

In contrast, the Earth's iron core is about 30 percent of the planetary mass.

This iron core is the aggregate of all professional journalism done by news organizations.

For an instant, it seemed the iron core of the blade would hold.