Page 17 - Curriculum Visions Dynamic Book

Scientists can analyze the pattern of colours. Each element has a unique “fingerprint” of light. By analyzing the Sun’s light and how brightly it shines at certain wavelengths, it was possible in 1925 for Cecilia Payne to discover not only that the Sun consists mainly of hydrogen and helium, but that the proportions are nine to one.
Helium, incidentally, was first discovered in the Sun—at that time it had not been found in nature on Earth. As a result, it was named for the Greek word for the Sun—helios.
Later analysis showed that the Sun also contains small amounts of most other elements, especially carbon, nitrogen, oxygen, magnesium, silicon, and iron, just like most parts of the universe.
atmosphere The envelope of gases that surrounds the Earth and other bodies in the universe.
atom The smallest particle of an element. core The central region of a body.
density A measure of the amount of matter in a space.
earthquake The shock waves produced by the sudden movement of two pieces of brittle crust.
element A substance that cannot be decomposed into simpler substances by chemical means.
gravitational field The region surrounding a body in which that body’s gravitational force can be felt.
gravity The force of attraction between bodies.
helioseismology The study of the internal structure of the Sun by modeling the Sun’s patterns of internal shock waves.
magnetism An invisible force that has the property of attracting iron and similar metals.
plasma A collection of charged particles that behaves something like a gas. It can conduct an electric charge and be affected by magnetic fields.
pressure The force per unit area.
radiation The transfer of energy in the form of waves (such as light and heat) or particles (such as from radioactive decay of a material).
radius (pl. radii) The distance from the center to the outside of a circle or sphere.
ultraviolet A form of radiation that
is just beyond the violet end of the visible spectrum and so is called “ultra” (more than) violet. At the other end of the visible spectrum is “infra” (less than) red.
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