Earth
It is the only one
with liquid water
on its surface, and
the only one that is
certain to support
life.44
Earth
The temperature of the core of
the Earth is about 6,500 K
This core is kept hot by
radioactive decay.
The rotating, metallic core
also creates a magnetic field
around the Earth.
The magnetic field of the
Earth change with time.
It weakens, reverses its NorthSouth polarity, and
strengthens again on time
scales of about 105 years.
oceanexplorer.noaa.gov/.../magfield_600.html