| A | B |
|---|
| Comets | "dirty snowballs" |
| Asteroid | Smaller than a planet (planetoid) |
| Comet Halley | Short Period Comet |
| Geocentric Distance | Comet's distance from the Earth |
| Heliocentric Distance | Comet's distance from the sun. |
| coma/tail | Two parts of the comet we see from earth |
| Edmond Halley | Predicted Comet Halley's orbit |
| Year 2061 | Next sighting of Comet Halley |
| Anti-tail | Tail points towards the sun due to heavy dust particles. |
| Absolute Magnitude | Brightness of a comet |
| Astronomical Unit | Measurement of distance in the solar system. |
| Short-period comets | Orbital period is less than 200 years. |
| Ellipse | describes the orbits of the planets. |
| Galileo | First to use a telescope to study stars. Discovered the moon. |
| Ice | refers to water, methane, and ammonia which occur as solids in solar system. |
| Inferior planets | planets whose orbits are closer to the sun. |
| Red Giant | Star having low surface temperature, and large diameter. |
| Light Year | Distance light travels in one year. |
| Meteor | Small, icy particle entering the Earth's atmosphere. |
| Meteorite | Extra-terrestrial rock found on the Earth. |
| Meteoroid | Small, rocky object orbiting around the Sun. |
| Photosphere | Visible surface of the Sun. |
| Planet | Object orbiting a star, bigger than an asteroid. |
