| A | B |
|---|
| Asteroid belt | The area between the inner and outer planets that is filled with asteroids |
| Astronomy | The study of the universe and all of the bodies that appear in the skies |
| Axis | A straight line that an object or body rotates or seems to rotate around |
| Blue moon | The second blue moon in the same calendar month |
| Constellation | Bright stars grouped according to the pattern they make in the sky. There are 88 |
| Nicolaus Copernicus | A polish scientist who re-introduced the idea that the Sun was the centre of the solar system |
| Emit | To send or give out |
| Eclipse | When the moon passes in front of the sun, either partially or fully |
| Equinox | During the sun's annual path in the sky it crosses the celestial crater at 2 celestial points, March 21 and September 23, where each day has 12 hours of day and night |
| Galaxy | A spiral of stars in space, ours is the Milky way |
| Gibbous | A phase in the moon cycle when more than half of the moon is illuminated |
| Inner planets | The four rocky planets |
| Lunar eclipse | when the moon moves into the earth's shadow, preventing sunlight from falling onto the moons surface |
| Magnitude | A 6-class scale used to measure the brightness of stars. 1 is brightest, 6 is dimmest |
| Moon | The name of the satellite that orbits earth |
| Moon phases | A cycle in which the moon appears in different forms as it revolves around another body in space |
| Orbit | The path of a planet as it revolves around another body in space |
| Outer planet | The 4 gaseous planets |
| Pole star | also known as Polaris, it appears in the northern hemisphere. It seems to always stay in the same position |
| Revolution | The motion of a planet |
| Rotation | The motion of a planet satellite, or the sun around its north-south axis. It takes 24 hours for earth to rotate on its axis |
| Solar eclipse | when the moon passes in front of the sun |
| Solar system | The sun and all of the bodies- planets, satellites, asteroids, comets, etc. that orbit around it |
| Solstices | Once a year the sun reaches its highest and lowest points in the sky at noon. In the northern hemisphere the least amount of daylight is december 21, and greatest number is June 21 |
| Stars | A gaseous body that produces its own energy, releasing light and heat |
| Sun | The closest star to earth, measuring more than 1,000,000 km across |
| Sundial | A device used to tell time |
| Universe | Everything that exists- The Earth, sun, moon, and all the galaxies in between them |
| Waxing moon | When the moon grows gradually more illuminated from the right when passing from new to full moon |
| Year | The time it takes for a planet to go all the way around the sun. for Earth it's 365 days, and for uranus it's 84 Earth years |
