It's applicable everywhere.
The matter is anything that takes up space. Energy is basicly the same as matter.
Energy coming to the earth and radioactivity are not same. Energy comes mostly from the sun and other parts of space. The energy of radioactivity is already bound up inside of the atom.
they use light-years to determine the space between objects in space
Radiation, e.g. in case of the heat from Sun, solar radiation transfers it to the planets and other outer space objects.
gravity?
What orbiting man made objects in space are powered with solar energy
Objects in space that can only be viewed from earth becouse of reflected light energy are said to be
The matter is anything that takes up space. Energy is basicly the same as matter.
objects in space that can only be viewed from earth because of reflected light energy are said to be luminous.
If you leave earths gravitational field (sufficiently), objects will have a very negligible gravitational potential energy. You can consider it zero. But what if it were a compressed spring that you brought out into 'deep space'? It would still retain elastic potential energy. A bomb in deep space would still have explosive(?) potential energy. With that said, if you had two or more objects in deep space, they would have gravitational potential energy between the group of them, but not the earth.
Stars, satellites, and something else
hi hi
Illuminated.
No, a physicist studies motion, energy and similar things. An astronomer studies objects in space, though not necessarily the physics of those objects. People who study the physics of objects in space are called astrophysicists.
Those would be heating elements such as on stoves and in space heaters.
anything but stars
radiation