The Solar System

1. The Solar System by, Drew Harris 

2. What’s a Solar System? A solar system is a set of satellites floating around a central star. A satellite is an object that floats around another object. A star is a large sphere of burning gases. Our solar system is where the planets, including Earth, orbit the sun, or rotate around it. A planet is a large object that moves around a star. Our solar system is a solar system because the sun is a star. It is also the only star in our solar system. Our sun is only a medium size star.

3. Why does Day and Night Occur? Day and Night occur because the sun is Earth’s main light. The part of Earth having day is facing the sun. The part of Earth having night is facing away from the sun.

4. Why do we haveDifferent Seasons? We have different seasons because of the tilt of Earth’s axis. Axis is the imaginary line that goes through the Earth. Almost all of the planets have a tilt in it’s axis. In fact, Mercury is the only planet without a tilt in it’s axis. Uranus is tilted so far it’s tipped over and on its side!

5. What’s the Difference Between a Planet and a Star? A planet looks and moves different from a star. Stars are different in size and color. Our sun is actually a small star, it only appears big because it’s so close to us. The color of a star depends on how hot it is. Red stars are the coolest and blue stars are the hottest.

6. How many Stars are there? There are more stars than one person can count in an entire lifetime.

7. Constellations • What is a constellation? • Constellations are totally imaginary things that poets, farmers and astronomers have made up over the past 6,000 years to help us tell which stars are which. On a really dark night you can see about 1,000 to 1,500 stars. • The northern hemisphere’s signpost is the Big Dipper. • Where did constellations come from? • Farmers used the constellations to help them know when to plant and when to harvest their crops because different constellations are visible at different times of the year. • There are 88 constellations. • Stars do not appear to move because they are so far away from the Earth.

8. Why do Constellationlocations change? Stars are grouped together in patterns called constellations. Constellation locations change by the Earth turning on it’s axis. This may be how it moves in the sky. Stars do move. Different stars can be seen in different seasons. Stars also have different colors and sizes.

9. How are planets andstars alike and different? Planets stars • look like a point of light in the night sky. • appear to change their positions. • just a few can be seen. • are closer to us than stars. • look like a point of light in the night sky • appear to not change their positions. • many can be seen. • do not change locations on different days. • are further away from us than planets.

10. What are the planets inorder from the sun? It’s “My Very Energetic Mother Just Served Us Noodles.” That’s a mnemonic device, or a way to remember (memory aid), the order of the planets. The order is: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

11. Mercury

12. Mercury Mercury is the closest planet to the sun and is about the size of Earth’s moon. It even looks like the moon. It has the temperature range of 800.6-361.4 F. It rotates, or turns, on its axis every 58.9 days and revolves, or circles, the sun every 87.9 days. Mercury has no moons and is the smallest planet. Galileo Galilei discovered Mercury in 1610. Mercury is 1/3 the size of the Earth.

13. Venus

14. Venus – 2nd planet from the sun If Earth had a twin it would be Venus. They are similar in size, mass, composition, and distance from the sun. However, Venus is very dry and has a thick atmosphere that transfers heat. It has a thick, swirling cloud cover. The atmosphere presses down100 times that of Earth. Venus is the second planet from the sun, in between Mercury and Earth. Venus rotates east to west so the sun rises in the west and sets in the east (opposite of the Earth). Venus has a cloud covering it, but we know that it has vast plains covered by lava and mountains with many craters. Venus is the hottest planet with a temperature of 899.6 F. Venus has no moons or oceans. Venus has been visited by more spacecraft than any other planet. It has a thick atmosphere of carbon dioxide and other poisonous gases. A space probe is an uncrewed space vehicle that carries cameras, instruments, and other research tools.

15. Earth

16. Earth Earth is the only planet known to have life. It’s the 3rd planet from the sun and the 5th largest. Earth is 70% covered with oceans. The oceans have the most life (habitats). Earth is the only planet with liquid water and the largest of the inner planets. Earth has an atmosphere that protects us from meteors. The Earth was last in its present position in the Milky Way at the beginning of the age of Dinosaurs. The 1st artificial satellite of Earth was Sputnik 1 U.S.S.R. Earth has one moon. It takes Earth 23.93 hours to rotate around its axis and 365.26 days to revolve around the sun. Earth’s atmosphere is mostly made of nitrogen and oxygen.

17. Mars

18. Mars Mars, the fourth planet from the sun, is known as the Red Planet because of chemical weathering of its iron rich rocks and was thought of as the most likely planet to hold life besides Earth. Mars may have held life long, long ago. They also believe that the dryness of the soil, the sun’s ultraviolet radiation, and the soil chemistry prevent life on Mars. Mars is most like Earth of all planets. It has polar ice caps and seasons. Mars has two moons. Mars’ atmosphere is carbon dioxide. Water ice was found on Mars in June 2008. Mars has the largest volcano in the solar system called Olympus Mons.

20. The Inner Planets

21. The Inner Planets The 1st four planets, Mercury, Venus, Earth, and Mars, are known as the InnerPlanets and terrestrial planets, or most likely to be possible to have life, because of their rocky surfaces. There is an asteroid belt separating the inner and outer planets. Asteroids are small, rocky objects that move around the sun.

22. Jupiter

23. Jupiter Jupiter, the fifth planet from the sun, has 50 known moons, a ring system of three, and a complex atmosphere. Jupiter is the largest planet in the solar system and outer planets. It’s so big that it’s bigger than all the other planets combined. It has an “Easter egg” appearance due to its many different colors. It’s mostly known for its Great Red Spot, a hurricane-like storm cell so big it could swallow Earth. It’s lasted for over 300 years. Galileo Galilei discovered four of Jupiter’s moons. Jupiter has three thin, barely visible rings.

24. Saturn

25. Saturn Saturn is the 6thplanet from the sun and one of the outer planets. Saturn is a giant, gaseous planet and has seven rings and 53 known moons. Saturn is so light it could float. Wind on Saturn is 10 times stronger than a hurricane. Saturn is the most distant planet visible without a telescope, or a tool to make things in space appear closer. Galileo Galilei discovered Saturn’s rings in 1610. The other two planets can be seen with atelescope.

26. Uranus

27. Uranus Uranus has 27 moons and 11 rings. The 1st nine were discovered in 1977. Uranus looks blue green because of methane gas in its atmosphere. Uranus is tipped on its side, maybe because of a collision with a planet sized object like a comet or asteroid. A comet is a small mass of dust and ice that orbits the sun in an oval shaped path. Sir William Herschel discovered Uranus in 1781. All the asteroids put together would make an object less than half the size of Earth’s moon.

28. Neptune

29. Neptune Neptune is the 8th, and furthest planet from the sun. Johann Galle discovered Neptune in 1846. It has 13 moons. It also has four rings. Neptune is aqua blue because its clouds contain methane ice crystals and has the strongest winds of any planet.

30. The Outer Planets

31. The Outer Planets On the other side of the asteroid belt are the outer planets. They are Jupiter, Saturn, Uranus, and Neptune. They are all large and made mostly of gases so they’re called the gasgiants. They are mostly hydrogen and helium.

32. Comets Comets are dirty leftovers from the creation of our solar system about 4.5 billion years ago. Most come from a distant region called the Oort Cloud about 100,000 astronomical units from the sun. There is another belt that orbits the sun outside of Pluto called the Kuiper Belt.

33. Dwarf Planet Pluto

34. Dwarf Planet Pluto Pluto isn’t a planet, but a dwarf planet because its orbit changes. It is smaller than the normal planets and it has a moon (Charon) that is close to its own size. Pluto’s moon, Charon, is smaller than Earth’s moon. Pluto has never been visited by spacecraft. Pluto was discovered in 1930. Every 20 years, Pluto trades places with Neptune (is in front of Neptune). From Pluto the sun looks like a very bright star. Little heat or light reaches Pluto or its three moons. Pluto is 6 billion Kilometers from the Sun.

35. The Sun

36. The Sun The sun is the only body in our solar system that gives light of its own and is the source of almost all the energy in our solar system. It’s over 100 times wider than Earth. It takes up as much space as 1,000,000 (1 million) planets the size of Earth. The sun is mostly hydrogen which is basically its fuel. The sun is a star and has been shining for nearly 5,000,000,000 (5 billion) years. One revolution of the Earth around the sun is one year. Revolution is the movement of any object in an orbit. The dark areas of the sun are called sunspots which are cooler than the rest of the sun’s surface and do not give off much light.

38. The Moon

39. The Moon The moon is about ¼ the size of Earth. The moon’s outer crust was shed during its formation leaving an egg shape. That shape makes the same side face the Earth at all times. Galileo Galilei discovered the moon in 1610. The Apollo 11 mission went to the moon in 1969. There Armstrong stepped on the moon and said the famous quote, “That’s one small step for man; one giant leap for mankind!”

40. The Moon … continued The reason the moon changes shape is that the moon’s light is actually being reflected off of the sun. It uses that light to reflect light so it doesn’t really change shape.

42. Vocabulary satellite – An object that moves around another object in space; the moon is a satellite of Earth. orbit – The path that an object such as a planet makes as it revolves around a second object. phase – One of the different shapes the moon seems to have as it orbits around Earth. revolution – The movement of any object in an orbit, such as Earth moving around the sun. axis – An imaginary line which runs through both poles of a planet. rotation – The motion of a planet or other object as it turns on its axis. solar system – A group of objects in space that move around a central star. star – a huge, burning sphere of gases; for example, the sun. planet – A large object that moves around a star. asteroid – A small rocky object that moves around the sun. comet – A small mass of dust and ice that orbits the sun in a long, oval-shaped path. inner planets – The planets closest to the sun; Mercury, Venus, Earth, and Mars. outer planets – The planets farthest from the sun; Jupiter, Saturn, Uranus, and Neptune. Gas giants – Planets which are large spheres made up mostly of gases – for example Jupiter, Saturn, Uranus, and Neptune. telescope – A device people use to observe distant objects with their eyes. space probe – An uncrewed space vehicle that carries cameras, instruments, and other research tools.

43. Facts Our Solar System – in order from the sun: Sun – Mercury – Venus – Earth – Mars – Jupiter – Saturn – Uranus – Neptune The sun is about 150,000 kilometers (93 million miles) from the Earth. It would take you about 193 years to travel this distance in a car at highway speed! About 500,000 craters can be seen on the moon through telescopes on Earth. It would take you more than 400 hours to count them all. And this doesn’t include the craters on the far side of the moon! Like most of the planets, Earth has seasons because it is tilted on its axis. But no planet is tilted like Uranus. Uranus is tilted so far that it is tipped over on its side! This gives Uranus a winter that lasts about 21 years! How the Tilts of the Planets Compare: Planet Degrees of Tilt Mercury 0 Venus 177 Earth 23 Mars 25 Jupiter 3 Saturn 25 Uranus 98 Neptune 28 Background Information: Johannes Kepler’s Laws of Planetary Motion – Johannes Kepler, a German mathematician who lived from 1571 to 1630, recognized that planets travel around the sun in elliptical rather than circular orbits. His observations resulted in what are now called Kepler’s three laws of planetary motion: 1. All planets move in elliptical orbits having the sun as one focus (Law of Orbits). 2. A line joining any planet to the sun sweeps out equal areas in equal times (Law of Areas). This means that the velocity of a planet is different at different places in its orbit. 3. The square of the orbital period (year) of any planet about the sun is proportional to the cube of the planet’s mean distance from the sun (Laws of Periods).