Unit 1: Discovering New Worlds

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Universe

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The totality of known or supposed objects and phenomena throughout space; the cosmos; macrocosm.

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Galaxy

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A massive, gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter.

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Milky Way

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The galaxy that contains our Solar System, with the name describing the galaxy's appearance from Earth.

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Light-year

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A unit of astronomical distance equivalent to the distance that light travels in one year, which is approximately 5.88 trillion miles (9.46 trillion kilometers).

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Star

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A luminous sphere of plasma held together by its own gravity, often visible in the night sky.

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Planet

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A celestial body moving in an elliptical orbit around a star.

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Exoplanet

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A planet that orbits a star outside the solar system.

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Orbit

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The gravitationally curved trajectory of an object, such as the path of a planet around a star.

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Spectroscopy

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The study of the interaction between matter and electromagnetic radiation as a function of wavelength or frequency.

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Elliptical orbit

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An orbit in the shape of an ellipse, which is an elongated circle.