The Sun

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Light-year Noun

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[lite-yeer]

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Light-year

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The distance light travels in a vacuum in one year, a unit used for measuring vast astronomical distances.

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Example: This diagram shows a light-year is a unit used to measure the vast distance between stars, like the 4.2 light-year distance from our Sun to Proxima Centauri.

Front

Luminosity Noun

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[loo-mi-nos-i-tee]

Back

Luminosity

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The total intrinsic amount of energy a star or other celestial object radiates per unit of time.

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Example: The Sun, a star, has high luminosity, meaning it emits a large amount of energy as light and heat, which travels through space to Earth.

Front

Electromagnetic radiation Noun

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[eh-lek-tro-mag-net-ik ray-dee-ay-shun]

Back

Electromagnetic radiation

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A form of energy propagated as waves, including a spectrum of visible light, gamma rays, and radio waves.

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Example: This diagram shows the electromagnetic spectrum, a range of energy waves from high-energy gamma rays to low-energy radio waves, including the visible light we see.

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Intensity Noun

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[in-ten-si-tee]

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Intensity

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The measure of radiation's power per unit area, which diminishes with the square of the distance from its source.

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Example: Energy from a source like the Sun spreads out as it travels; the same amount of energy covers a larger area, so its intensity decreases with distance.

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Nuclear fusion Noun

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[noo-klee-er fyoo-zhun]

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Nuclear fusion

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A nuclear reaction where atomic nuclei combine to form heavier nuclei, releasing a tremendous amount of energy.

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Example: Two small atomic nuclei, Hydrogen-1 and Hydrogen-2, combine (fuse) to form a larger nucleus, Helium-3, releasing a large amount of energy.

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Combustion Noun

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[kom-bus-chun]

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Combustion

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A rapid chemical reaction between a substance and an oxidant, usually oxygen, to produce heat and light.

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Example: This diagram shows combustion, a chemical reaction where a fuel (candle wax) reacts with oxygen (O₂) to produce heat, light, carbon dioxide (CO₂), and water (H₂O).

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Proton-proton chain Noun

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[pro-ton pro-ton chayn]

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Proton-proton chain

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The main sequence of nuclear fusion steps by which stars like the Sun convert hydrogen into helium, releasing energy.

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Example: This diagram shows how the Sun creates energy by fusing hydrogen nuclei (protons) into one helium nucleus through a multi-step process.

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Deuterium Noun

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[doo-teer-ee-um]

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Deuterium

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A stable isotope of hydrogen with a nucleus containing one proton and one neutron, making it heavier than ordinary hydrogen.

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Example: This diagram shows that Deuterium is a type of hydrogen atom that has one proton and one neutron in its nucleus, making it heavier than regular hydrogen.

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Positron Noun

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[poz-i-tron]

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Positron

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The antimatter equivalent of an electron, possessing a positive electric charge and the same mass as an electron.

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Example: This diagram shows that a positron is a particle that, when it meets an electron, annihilates to release energy in the form of a photon.

Front

Neutrino Noun

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[noo-tree-no]

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Neutrino

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A neutral subatomic particle with a tiny mass that interacts weakly with other matter, produced in nuclear reactions.

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Example: This diagram shows a neutrino particle (ν) originating from the Sun and traveling in a straight line, passing completely through the Earth without being stopped.