More accurately, astronomers will send the light through a prism and measure how much radiation there is at each wavelength. The object's temperature is found from where the peak wavelength occurs. Not all objects behave as we just described. Section 3.3 - Atoms Atoms are mostly empty space. Atoms have a tiny central area called the nucleus .
Opposite charges attract.
See figure 3.7 on page 103 . This electrical attraction holds the electron in orbit like gravity holds planets in orbit around the Sun. The nucleus contains protons, which repel each other. But further experiments revealed some very surprising results. It was Neils Bohr who first figured out how to modify this model to fit all the experimental evidence.