Astronomy Vocabulary

•1. Electromagnetic Spectrum: Waves of particles that travel at the speed of light.

2. Doppler Shift: Objects moving away

show a redshift. Objects moving closer show a

blueshift.

•3. Radio Telescope: Gathers radio waves and feeds the information to a computer. (Radio)

•4. Reflecting Telescope: Uses a mirror to gather light. (Optical)

•5. Refracting Telescope: Uses a convex and concave lens to gather light. (Optical)

•6. Big Bang Theory: 14.6 Billion years ago, the universe began in a giant explosion.

•7. Galaxy: A group of millions or billions of stars.

•8. Nebula: A cloud of Hydrogen and Helium gas in space.

9. Parallax: The angle that is created between the Earth

and the sun as the Earth orbits.

•10. Light-Year: The distance light travels in one year.

•11. Main Sequence: Stars that follow a “normal” life cycle.

12. Astronomical Unit: (AU) The distance from the Sun to the Earth. (About 93 million miles.)

•13. Comet: An object made of ice and dust that orbits the sun.

•14. Meteor: A small rock in space. Meteoroid: Burning in our atmosphere. Meteorite: Hits the ground.

•15. Asteroid: A rock in space that is larger than a mile across.

•16. Satellites: Objects that orbit. Natural = Planets, moons, asteroids, etc. Artificial = man made. (spacecraft)

17. Geocentric: The earth is at the center of the universe.

18. Heliocentric: The sun is at the center of the solar system.

19. Nicholas Copernicus: Was the first to believe that the sun was the center of the solar system.

20. Galileo Galilei: The first Astronomer to use a telescope. Found evidence to support Copernicus.

21. Johannes Kepler: Used math to form his 3 laws of planetary motion. Found that planets orbit the sun in ellipses.

22. Ellipse: An elongated circle with two foci.

•23. Aphelion: The farthest distance in an orbit.

•24. Perihelion: The closest distance in an orbit.

The Sun Earth Aphelion

Earth Perihelion

•25. Sphere: A round 3 dimensional object.

•26. Axis: The imaginary line that a planet rotates around.

•27. Rotation: A planet spinning on its axis. (A DAY IS ONE ROTATION)

•28. Revolution: One orbit around the sun. (A YEAR IS ONE REVOLUTION)

• 29. Solar Eclipse: The moon gets between the Earth and the sun and makes a shadow on the Earth.

• 30. Lunar Eclipse: The Earth gets between the Sun and the moon and makes a shadow on the moon.

• 31. Planetesimal: (Dwarf Planet) An astronomical body too small to be defined as a planet (2006 – Pluto)

•32. Nebular Theory: The sun and planets formed from a rotating disk of gas and dust.

•33. Nuclear Fusion: Stars combine elements (Lighter to Heavier) To produce energy.

•34. Terrestrial: Planets that are made of rock.

•35. Jovian: Planets that are made of gasses.