The photon. This refers to the "rest mass"; since the photon has energy, it also has an associated mass. But the "rest mass" or "invariant mass" is zero.

A Zeuthen-Segre invariant is an invariant of complex projective surfaces.

A body's mass is invariant regardless of its position in space. Therefore, the chair's mass on Mercury will be identical to the chair's mass on Earth, that is 10 kilograms.

the mass is an invariant: so 25kg mass would still be 25kg mass where ever it was.

the force a 25kg mass exerts would change,

as the force is a variant that would be altered by the lower gravitational strength of the moon.

Any object has two masses associated.What is sometimes called the rest mass, or invariant mass, for the photon (piece of light), is zero.

Its relativistic mass is equal to its energy divided by c squared.