| A | B |
|---|
| star | a very large mass of hot glowing gases |
| planet | a large body of matter that moves around a star such as the sun |
| solar system | the sun, the planets and their moons, and other objects that move around the sun |
| crater | a large hole in the ground that is shaped like a bowl |
| Mars | called the red planet, has two moons |
| Venus | about the size of Earth, hot, thick clouds, no moons |
| Uranus | green in color, lies on its side, seventh from the sun |
| Pluto | smallest, and farthest from the sun, not yet explored |
| Mercury | closest to the sun, very hot, covered with craters |
| Neptune | large, blue, eigth in order from the sun |
| Jupiter | largest in the solar system, made mostly of gas |
| Saturn | very bright, has many rings, made of gas |
| Earth | covered with water, has air, third from the sun, supports life |
| axis | an imaginary, straight line through the center of the Earth |
| rotate | to spin on the axis |
| orbit | the path an object follows as it moves around another object |
| revolution | movement of an object in an orbit around another object |
| rotation | causes day and night |
| year | the time the Earth takes to go around the sun |
| seasons | caused by the tilt of the Earth's axis |
| 3 months | about how long each season lasts |
| The Hubble Space Telescope | can see things in space that cannot be seen by telescopes on Earth |
| Why can we study the universe bettter than 100 years ago? | because we have telescopes and other instruments |
| Why does the moon appear to have different shapes? | because different parts are lighted at different times |
| Why can't the moon support life? | because there is no air or water |
| why is a year on Earth 365 days? | because that is how long it takes the Earth to revolve around the sun |
| Why is the midle pat of the Earth warmer than other areas? | because the sun's rays shine on it in straight line |
| Why can't we see the stars in the day? | because the sun is so bright |
| Why do sunspots appear darker? | because they are cooler than other areas around them |
| Why can Earth support life? | because there is air and water |
| Why is Uranus different from other planets? | because it lies on its side |
| Why is there day and night? | because Earth rotates on its axis every twenty-four hours |
| satellite | an object that revolves around another object |
| February | the month with the fewest days |
| What is the period of time on Earth that is about 30 or 31 days? | a month |
| gravity | causes the oceans and sea tides |
| What phase can the moon not be seen in? | new- moon phase |
| When it is winter on the north half of the Earth it is summer on the... | south side of the Earth |
| phases | the lighted parts of the moon that we see |
| Wha part of the Earth gets less sunlight? | the part tilted away from the sun |
| tide | rise and fall of the ocean |
