| A | B |
|---|
| Astronomy | The study of the moon, stars, and other objects in space |
| Axis | Imaginary line that passes through Earth’s center and the North and South poles, which the Earth rotates around |
| Rotation | Spinning motion of an object around an axis (center point) – like the Earth spinning on its axis |
| Revolution | The movement of one object around another |
| Orbit | Path of an object as it revolves around another object in space |
| Geocentric | Model of the solar system that has Earth in the center and everything else revolving around it (other stars, moons, planets) |
| Heliocentric | Model of the solar system that has the Sun (our star) in the center and everything else (Earth, other planets, moons) revolving around it |
| Ellipse | Oval shape, which may be elongated (stretched out) or almost a circle |
| Solstice | The two days of the year that the Sun reaches its greatest distance north or south of the equator (longest/shortest amount of daylight/nighttime) |
| Equator | Imaginary line that circles the Earth halfway between the North and South poles |
| Equinox | The two days of the year that neither of Earth’s hemispheres is tilted toward or away from the Sun |
| Phases | One of the different apparent (looking) shapes of the moon as seen form the Earth |
| Eclipse | Partial or total blocking of one object in space by another |
| Solar Eclipse | Blocking of sunlight to Earth that happens when the moon is directly between the Sun and the Earth |
| Lunar Eclipse | Blocking of sunlight to the moon that happens when the Earth is directly between the Sun and the moon |
| Umbra | The darkest part of a shadow (for us, dealing with eclipses) |
| Penumbra | The part of the shadow surrounding the darkest part (for us, dealing with eclipses) |
