| At this point of its orbit, any solar satellite such as a comet or a planet is farthest away from the sun. |
What is the aphelion? |
| These small, rocky worlds orbit the sun generally between the orbits of Mars and Jupiter. |
What is an asteroid? |
| This collection of small, rocky bodies are found orbiting the sun, mostly between the orbits of Mars and Jupiter. |
What is the asteroid belt? |
| This type of scientist studies things outside the Earth's atmosphere. she or he may use telescopes to study the Moon, Sun, planets, stars, or galaxies. |
What is an astronomer? |
| This unit of length is equal to the average distance from the Earth to the Sun; about 150 million kilometers, or 93 million miles. |
What is an astronomical unit |
| This organic molecule is found in solid form in the nucleus of comets. On Earth, it is also present as a gas exhaled by humans and most animals. |
What is carbon dioxide? |
| The cloud of hot gas formed when a comet passes close to the sun, causing its ices to sublimate, |
What is the coma? |
| These small bodies are composed of ices and dust and orbit around the sun. They appear as bright, tailed stars when near the Sun. |
What is a comet? |
| This complex organic molecule contains the
"pattern" for a living being to reproduce. *expand the acronym for extra points |
What is DNA? |
| This type of comet tail is visible because it reflects sunlight, and usually appears curved. |
What is the dust tail? |
| Sometimes called a regular oval, this geometric shape, has two focus points, or foci. |
What is an ellipse? |
| This group of planets contain most of the non-solar mass of the solar system. *Name them for extra points |
What are the giant
planets? |
| This spacecraft was launched on July 2, 1985 to study Comet Halley. |
What is the Giotto satellite? |
| This neutral form of carbon is found in interstellar space as well as in pencils. |
What is graphite? |
| This matter fills the spaces between stars, and is composed of gas and interstellar dust. |
What is the interstellar medium? |
| This Dutch astronomer was the first to suggest that many comets come from a large cloud of debris ejected from the early solar system. |
Who is Jan Van Oort? |
| This band of small objects revolves around the sun outside the orbit of Neptune and is believed to be the source of short period comets. |
What is the Kuiper Belt? |
| This unit of length is equal to the distance that light travels in one year, or about nine and a half trillion (9,500,000,000) kilometers. |
What is a light year? |
| These comets come from the Oort Cloud and may take as long as tens of thousands of years to orbit once around the sun. |
What is a long period comet? |
| Bright streaks in the evening sky, sometimes called shooting stars, and caused by space debris that burns as it falls through Earth's atmosphere. |
What is a meteor? |
| Most of these fragments of debris left behind in the orbits of comets are very tiny. |
What is a meteoroid? |
| This beautiful event occurs when the Earth passes through a trail of debris along a comet's orbit, and the many bits of material burn up in the atmosphere. |
What is a meteor shower? |
| Extraterrestrial debris that reaches the ground before it is completely burned up in the earth's atmosphere. |
What is a meteorite? |
| This relatively small, solid core of a comet is made of ice, dust and rock and is usually hidden from view. |
What is the nucleus? |
| This cloud of early planetesimals forms a comet reservoir around the solar system, and is about 100,000 AU across. |
What is the Oort Cloud? |
| The path that a body in space follows as it revolves around another (for example, the earth around the sun). |
What is an orbit? |
| Compounds made up of the most common substances, or elements in living systems: carbon, oxygen, nitrogen, and hydrogen. |
What is organic matter? |
| At this point of its orbit, any solar satellite such as a comet or a planet is closest to the sun. |
What is perihelion? |
| The time required for a body like a comet or planet to go once around its orbit and return to the same spot. |
What is a period? |
| The planets were formed from these small chunks of dust, rocks and frozen gasses as they collided and stuck together. |
What are planetesimals? |
| A hot gas of charged particles. |
What is plasma? |
| This comet tail glows with its own light and always points straight away from the sun. |
What is the plasma tail? |
| To move around continuously on a closed path, like an orbit. |
What does it mean to revolve? |
| These comets are believed to come from the Kuiper Belt and usually take less than 200 years to revolve once around the sun. |
What is a short period comet? |
| The cloud of gas and interstellar dust from which the sun and eventually the whole solar system were formed. |
What is the solar nebula? |
| The sun and everything that revolves around it, including the planets and their moons, asteroids, comets, and all the objects in the Kuiper Belt and the Oort Cloud. |
What is the solar system? |
| Hot gases and magnetic fields that stream rapidly out of the sun in all directions at all times. |
What is solar wind? |
| When a solid, such as ice, changes directly into a gas or vapor without becoming a liquid first, it is said to go through this process. |
What does it mean to sublimate? |
| This American astronomer was the first to propose the "dirty snowball" model of comet structure. |
Who is Fred Whipple? |