Measurement of this slight deformation will tell whether the Moon's core has cooled and turned solid.

Before the discovery of its magnetic field in 1974, it was thought that because of Mercury's small size, its core had cooled over the years.

The pulsing core of the meteorite has never cooled in the countless centuries since.

But if the conductivity inside the Earth were much higher than at the surface, then the Earth's core and lower mantle would also cool.

The core quietly cooled itself down, and that was that.

Eons ago, they added, its inner core perhaps cooled into a solid mass.

After nuclear fusion comes to a stop, the core cools, leading to a reduction in the thermal pressure in the interior of the star.

The core grew cold, as the core of all other planets had cooled.

Eventually the entire core would cool and go essentially dormant.

The core can then expand and cool down and a stable burning of helium will continue.