Seth dropped his schoolbag and headed straight for the fridge. He needed a good snack if he was going to stay up late to watch the super perigee moon. He didn’t care about the moon, but Mr. Andrews assigned (布置作业) a project and expected him to do all that work in one night.

“Hungry?” Mom asked.

“Not really, but I have to eat something. Mr. Andrews is making me watch the moon tonight and write up information on it.”

“Oh, that’s right. Tonight is the super perigee moon.” Mom smiled. “What a fun assignment.”

Fun? Was she crazy? “I don’t think staying up late to stare (凝视) at the moon sounds like fun at all.”

Mom laughed. “You just wait. I’m sure you’ll enjoy it more than you think you will.”

Seth didn’t think so. Mr. Andrews told the class that the super perigee moon appears when the full or new moon is the closest to the Earth. They spent an entire class talking about how big the moon usually looks. Seth didn’t see why this was such a big deal.

When the sun set, Seth walked outside. “That’s strange,” he said to his dad, “It’s so bright out here.”

“The super perigee moon is about 30% brighter than usual,” Dad said. “When I was younger, Grandpa used to study astronomy. He taught me all about space. The super perigee moon was always one of my favorite things to look at.”

Seth stared at the moon. Not only was it bright, it was huge—bigger than any full moon he’d ever seen.

“About 40% larger than usual,” Dad said.

Seth opened the notebook and started to write down the information his dad told him. “Think I should take pictures for the assignment?”

“Why not? It’s a good idea. It would get you good marks.”

“And I’d like to have pictures to remember this. It’s pretty cool.”

“So I guess you’re not too upset that you have to do the homework after all,” Dad said.

Seth continued to stare in awe (无比崇敬地) at the super perigee moon. “I think it’s the best assignment we’ve had all year.”

5 . Earth is our home. It has air that we can breathe(呼吸). It has water for us to drink. It has plants and animals that we can eat. Earth is not too hot or too cold for us. It has everything we need to live.

We are on earth, but we can see things that are not on earth. Early in the morning, we can see the sun comes up. All day, the sun seems to move across the sky. Later in the day, we can see the sun goes down.

But the sun is not really moving around us. We are the ones who are moving. Every morning, we turn towards the sun. Every night, we turn away from it. Every year, we go around it. Earth is our spaceship. All of us in the spaceship are riding around the sun.

At night, we can often see the moon and stars. From earth, stars look like little points of light because they are so far away. But stars are really big. A star is a great mass(一团) of burning gas. It gives off light and heat. Our sun is a star.

There are eight planets moving around our sun. Earth is the third planet around the sun. Some of the planets have moons. A moon goes around a planet just as a planet goes around a star. Earth has only one moon. Some planets have more.

7 . Look up at the sky on a clear night, you will probably see a lot of stars. Do you ever think about the light (光）from these stars?     1    

First of all, when you see a star, in fact you are looking at the past(过去). Do you know why?     2     Their light can take many years to get to the Earth. For example, the star Proxima Centauri is around four light years away from our solar system. That is to say, we are seeing light from the star that is four years old. Many other stars are thousands of light years away. So the light we see from those stars is thousands of years old.

Secondly,     3     At first, they all seem to be the same. However, if you look a little more closely, you will find that the stars are different colors.     4     And some are even red or blue. There are a few reasons why stars are different colors.     5     Some are much hotter or cooler than others. Blue stars burn at very high temperatures while red stars burn at very low temperatures. It is interesting, isn’t it?

8 . Although air is all around us, we can’t see it. We can feel it and breathe it. The air that surrounds the Earth is called the atmosphere (大气层) and it is made up mostly of two gases nitrogen and oxygen. Gravity pulls on the gasses and keeps the atmosphere close to the Earth’s surface. This is good, because we need oxygen in order to live.

There are many layers in the atmosphere. Because of gravity’s pull, most of the air is in the bottom layer. When scientists talk about the atmosphere, they often use the word altitude. They measure altitude from sea level, which is the place where the land and sea are at the same level. There is a lot of oxygen at sea level.

As the altitude increases, the atmosphere has less gas. This means there is less oxygen to breathe. That’s why it is harder to breathe at the top of a mountain than it is at sea level.

You might have seen beautiful rainbows in the sky before. They form when sunlight falls on water drops in the air. But in fact, moonlight can also create rainbows in the same way. They are called “moonbows”. They are similar to rainbows, but they are created by moonlight instead of direct sunlight.

Moonbows are rarer than rainbows. Different weather and astronomical （天文学的）conditions have to be just right for moonbows to be created.

The moon has to be very low in the sky-only 42 degrees from the horizon （地平线）. The moon period has to be a full moon or nearly full. The sky must be very dark for a moonbow to be watched clearly-any bright light can obscure it. Water drops must appear in the air in the opposite direction of the moon.

Moonbows appear on the opposite side of the moon and usually look white to the human eye. This is because their colors are not bright enough to be noticed by the human eye. It is possible, however, to view the colors in a moonbow using long exposure （长时间曝光）photography.

Moonbows more often appear in some locations around the world. Most of these locations usually have waterfalls, which create thin fog in the air. Some of these locations are the Yosemite National Park in California and Cumberland Falls State Resort Park in Kentucky, US; Victoria Falls on the border of Zambia and Zimbabwe; and Waimea in Hawaii, US.

Moonbows do really happen. So at a certain time and a certain place, when a moonbow happens to appear, you can’t miss it if you’re right there.