The axis is an imaginary line going through the earth so the way the earth is "tilted" would tell you,for example, if the northern hemisphere is tilting toward the sun, it will be summer in the northern hemisphere.
Answer:
Radioisotopes are radioactive isotopes of an element
Explanation: Radioactive isotopes are detected by: photographic film.
a cloud or bubble chamber.
a liquid scintillation detector.
a Geiger-Muller counter.