Mission 1: What's in Our Sky

Mission 1 – page 1

Name: ______Teacher: ______

Mission 1: What's In Our Sky?

Mission 1: We need to learn more about how the Sun, Moon and Earth are alike and different so we can make the best decisions about how to grow plants on the Moon. You will learn all about them and report back on what you've learned to Commander Spud Goodroot.

Sections:

Sun and Stars The Moon Earth Dances Moon Dances Moon Visits

Sun and Stars

The Sun is the brightest object in our sky and the largest object in our solar system. The Sun is actually a star that is 93 million miles (that's 150 million kilometers) from the Earth. The Sun is about 4.5 billion years old and is one of more than 100 billion stars in our galaxy. Our galaxy is called the Milky Way Galaxy. The Sun is one of many stars in the part of our galaxy called the Orion arm.

The Milky Way Galaxy, courtesy of Windows to the Universe, http://www.windows.ucar.edu Mission 1 – page 2

The Earth and eight other planets move around the Sun in paths called orbits. Lighter objects orbit heavier ones, and the Sun is the heaviest object in the solar system. The Sun is more than 300,000 times heavier than the Earth.

The Sun is very large compared to the Earth. The diameter of the Sun is 100 times more than the diameter of the Earth! And, even at that size, it is just a medium- sized star compared to others.

The Sun is very hot! The temperature of the surface of the Sun is about 11,000 °F (degrees Fahrenheit). That's the same as 6093 °C (degrees Celsius). We will learn about temperature scales in Mission 4.

The Sun is a ball of gas made mostly of two gasses: hydrogen and helium. Helium is what goes into balloons to make them float. The Sun is always working to change hydrogen to helium. The Sun makes the light that we see and the heat that we feel when we are outside during the day.

The Sun is one of many stars in our galaxy. Our sun is an average star. Some others stars are much bigger and others are much smaller. All of the other stars in the sky are much further away from us than the Sun. Their long distance away from us is the reason they look like tiny points of light in the night sky.

We measure the distance of stars from Earth in light years. A light year is the distance that light travels in one year. Since light travels at a speed of 186,000 miles/second (300,000 kilometers/second), a star that is one light year away is actually 5.8 trillion miles (9.5 trillion kilometers) from us! The Sun is only 8 light minutes away. That means that light from the Sun takes 8 minutes to get to earth. By comparison, if your friend turned on a very bright flashlight in California, you would see the light in about 1/60th of a second. Thats very quick! That is quicker than snapping your fingers! The closest star to us, other than the Sun, is Alpha Centauri, and it is 4 light years away. The most distant stars we can still see without a telescope are about 1000 light years away! Mission 1 – page 3

All the stars we see at night from Earth are also stars in our Milky Way Galaxy. There are over 100 billion stars in our Galaxy, but on an average dark night we can only see about 1000 to 1500 of them! Stars produce light and heat by changing hydrogen into helium, just like the Sun (remember, the Sun is a star, too!).

Constellations are patterns of stars in the sky that have names. Constellations have been used for many years to help sailors navigate, or figure out where they are, in the ocean and also to remember stories about heroes and myths. Astronauts can use constellations in the same way. We see different constellations during different seasons as the Earth moves around the Sun. Mission 1 – page 4

The Moon

The Moon is the second brightest thing in the sky after the Sun, but it is not a star. The Moon is about ¼ the diameter of the Earth and is made of rocky material. Most lunar rocks are between 3 and 4.6 billion years old. Many scientists believe that the Moon formed when the Earth ran into a very large object (perhaps as big as the planet Mars). They think the Moon formed from the broken material. The Moon is the only natural satellite of the Earth and travels around the Earth in an The diameter of four orbit. Moons is equal to the diameter of the Earth.

The Moon is about 240,000 miles (386,000 kilometers) away from Earth. How long does it take for light to travel from the Earth to the Moon? About 1.3 seconds.

The temperature on the Moon is much colder, but strangely also much hotter than on Earth. It can get as hot as 212 °F (100 °C) and as cold as -233 °F (-147 °C)! This large temperature range happens because the Moon has no atmosphere. On Earth, our atmosphere helps to control the temperature on our planet. Since the Moon has no atmosphere to help with temperature control, it is very hot where the Sun shines on the Moon and it is very cold where the Sun does not shine! Because of the way it rotates, the moon's South Pole never gets any sunlight.

Man-made satellites that have orbited around the Moon have found some evidence of ice scattered in some of the deep craters near the Moon's North and South Poles. This means that there is frozen water on the Moon. Mission 1 – page 5

Earth Dances

The Earth revolves around the Sun every 365 days, and this is why our calendar has 365 days in a year. That means the Earth moves completely around the Sun one time each year. So why does the Earth orbit the Sun? Think of it like this: The Earth is spinning around the Sun just like you would twirl a ball on a string. If the string breaks, the ball flies off. Why doesn't the Earth "fly off" into outer space? That is because of gravity. Gravity is a natural force that attracts objects to each other. The Sun and the Earth are held together by gravity, so even though the Earth is spinning around the Sun, it remains in orbit because of gravity. This is the same reason why all of the planets orbit the Sun and also why the Moon orbits the Earth. Gravity is like the string that holds the twirling ball.

Gravity is the reason we keep our feet on the ground. We feel Earth's gravity pulling us down. Because the Moon is smaller than the Earth, there is less gravity. If you weigh 60 pounds on Earth, you would only weigh 10 pounds on the moon!

Earth's orbital path is created by two things: gravity and a sideways motion.

The Earth also has an axis, and it rotates on its axis every 24 hours. This is why there are 24 hours in a day. Revolution is when the Earth moves in a circle around the Sun, and rotation is when the Earth spins on its axis. Because the Earth rotates one time every 24 hours, at any point in a day, half of the Earth is facing the Sun and half of the Earth is facing away from the Sun. In North America, we have daytime when our continent is facing the Sun. North America has nighttime when our continent is on the side of Earth facing away from the Sun. So, when it is nighttime in North America, it is daytime in places on the other side of the Earth.

If we stood in the same spot outside for an entire day, it would look like the Sun was moving across the sky. It is really the Earth that is moving! As your spot on the Earth rotates toward the Sun, we see a sunrise, and as it rotates away, you see a sunset. The Sun appears to be directly above us in the sky at noon. Mission 1 – page 6

In the picture above, Rosy sees the Sun rise in the east because the Earth is rotating. She sees the Sun directly above her at noon, and then she sees the Sun set in the west - all because of the Earth's rotation.

So, we know that the Earth's rotation causes day and night. The Earth's revolution around the Sun also causes our seasons. The different seasons on Earth are caused by the tilt of the Earth's axis and the angle of the sunlight when it hits the Earth.

The Earth is not positioned straight up and down - it is tilted at an angle. So, for example, when the Earth is tipped towards the Sun, the northern hemisphere has summer. Summer in the northern hemisphere brings longer days (over 12 hours of sunlight a day!) and shorter nights. The sunlight during the summer is also hitting the Earth head on, which heats that part of the Earth. At the same time of the year, the southern hemisphere is having winter, which means less hours of daylight. The sunlight is not striking the southern hemisphere head on at that time, which causes less heating of the Earth in the southern hemisphere. Mission 1 – page 7

Moon Dances

We just learned that when one half of the Earth is lit up by the Sun, the other half of the Earth is dark. The same thing happens with the Moon. When the Moon is orbiting around the Earth, we see different parts of the Moon at different times. This makes the Moon seem to disappear slowly and then reappear. There are eight phases of the Moon, and the Moon cycles through all eight phases every 29 1/2 days. This is almost once a month. Mission 1 – page 8

Phase 1 - New Moon

Phase 2 -Waxing Crescent Moon

Phase 3 - First Quarter Moon

Phase 4 - Waxing Gibbous Moon

Phase 5 - Full Moon

Phase 6 - Waning Gibbous Moon

Phase 7 - Last Quarter Moon

Phase 8 - Waning Crescent Moon Mission 1 – page 9

What about gravity on the Moon? Gravity helps to keep the Earth orbiting around the Sun. In the same way, gravity helps to keep the Moon orbiting around the Earth. Remember, smaller objects orbit larger ones. The Moon is smaller than Earth, so the pull of gravity from the Earth is stronger. Does the Moon have gravity? Could objects be attracted or pulled towards the Moon by its gravity? Yes, but the gravity on the Moon is only 1/6 of that on the Earth. So, on the Moon, you would only weigh 1/6 of your weight on Earth. Mission 1 – page 10

Moon Visits

When a satellite or spacecraft circles close to Earth, we say it is in Low Earth Orbit (LEO). Because these satellites and spacecraft are traveling so close to Earth, they must travel at very high speeds so that Earth's gravity does not pull them back into the atmosphere. Satellites and spacecraft in LEO can circle the entire Earth in about 90 minutes! This high-speed travel creates a state of freefall, and things in free-fall are said to be "weightless". This state is also called microgravity environment. In microgravity, people do not feel the effects of gravity. This is the reason we see pictures of astronauts floating around on spacecraft. There is no gravity to keep them firmly grounded.

The Moon was first visited by a Russian spacecraft called Luna II in 1959. The first time humans visited the Moon was on July 20, 1969 when Neil Armstrong was the first person to step onto the Moon. The last time anyone visited the Moon was in December 1972.

The Moon is the only extraterrestrial body that humans have visited. Many people want to go back to the Moon, and other people want to go to planets such as Mars or to other objects in the galaxy such as asteroids. Mission 1 – page 11

Sky Report

Look back at the information you have learned and write a report on the following page to Commander Spud Goodroot answering the following questions:

1. How is the Moon different from the Earth and the Sun? Refer to your chart for help.

2. Why does part of the Moon seem to "disappear" and then come back?

3. Do you think people or plants could live on the Moon right now? Why or why not?

4. If you had to decide right now, is there anywhere on the Moon where you would NOT put the plant growth chamber? Why?

Congratulations! You have completed Mission 1! Mission 1 – page 12

Mission 1 Glossary angle what lies between two rays which share the same endpoint asteroid a rocky object in space that can be anywhere from a few feet wide to several miles wide. Most asteroids in our solar system are part of a belt between Mars and Jupiter. atmosphere the mass of gas surrounding an object in space and held by the object's gravitational field axis an imaginary straight line around which an object spins. The Earth's axis is tilted 23.45 degrees. billion A number represented as a 1 followed by nine zeros (1,000,000,000). If you have a bucket that holds 10 thousand marbles, you would need 100 thousand of those same buckets to hold a billion marbles! That's a lot of marbles!

Celsius metric temperature scale at which water freezes at 0° and boils at 100° crater a bowl-shaped depression on a surface made by the impact of a large object, such as a meteor diameter a straight line segment which passes through the center of a circle or sphere with both its ends on the boundary of the circle extraterrestrial originating or occurring outside the Earth and its atmosphere; when scientists search for extraterrestrial life, they are trying to find life on someplace other than Earth

Fahrenheit the temperature scale at which water freezes at 32° and boils at 212° freefall another term for the feeling of "weightlessness" galaxy a huge collection of gas, dust, and stars in space. Our own galaxy is called the Milky Way. gravity the natural, invisible force between objects that attracts them to each other Mission 1 – page 13

heat a form of energy that causes the sensation of feeling hot or warm kilometer A unit of measure for length. One kilometer equals 1,000 meters. A kilometer is also equal to .6214 miles. light electromagnetic radiation that has a wavelength that is visible to the naked eye light year the distance that light can travel in one year (9.5 trillion kilometers)

Low Earth Orbit An area that satellites travel in that is about 200-500 miles (320-800 kilometers) above Earth. Satellites traveling in Low Earth Orbit have to travel very fast so that gravity does not pull them back out into the atmosphere.

Luna II Russian spacecraft, the first spacecraft to land on the Moon. Humans were not on this spacecraft. It landed on the Moon on September 14, 1959. lunar having to do with the Moon microgravity an environment in which there is minimal gravitational force

Moon can be any natural object orbiting around another; often refers to the Moon of the Earth (but other planets have moons too.) The Moon of the Earth was probably formed when a large object struck the Earth a long time ago. navigate to plan, record and control the movement of a ship or plane Moon - can be any natural object orbiting around another; often refers to the Moon of the Earth (but other planets have moons too.) The Moon of the Earth was probably formed when a large object struck the Earth a long time ago.

Neil Armstrong American astronaut and the first person to step on the Moon. When he landed on the Moon, he said, "That's one small step for man; one giant leap for mankind." orbit the path followed by an object in space as it travels around another object Mission 1 – page 14

phase one of the apparent forms of the Moon. The Moon cycles through 8 phases. revolve to move in an orbit or circle around something rotate to move around a center point, or axis, just like how a wheel rotates satellite an object that orbits another in space. The Moon is a natural satellite of the Earth. star an object in space composed of intensely hot gasses that creates light and heat energy from nuclear reactions going on inside of it

Sun a star, and the largest object in our solar system. The Sun is the closest star to Earth and is about 5 billion years old. telescope an instrument used for viewing far away objects, such as planets and stars temperature the degree of hotness or coldness of a body or environment trillion A number represented as a 1 followed by twelve zeros (1,000,000,000,000) If you have a bucket that holds 100 thousand marbles, you would need 10 million of those same buckets to hold a trillion marbles! That's a lot of marbles! weightless not experiencing the effects of gravity