The document provides an overview of the solar system, including information about the sun, planets, and other celestial bodies. It discusses the inner and outer planets, as well as characteristics of specific planets like Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. It also covers moons, asteroids, comets, dwarf planets, and phases of the moon. The summary focuses on key details about the structure of the solar system and different types of objects within it.

1. Space:the Final Frontier

2. Space Lesson 1The Earth and the Sun

4. Earth Earth moves in two ways: Earth rotates, or spins, on its axis. An axis is an imaginary line through both poles.It takes about 24 hours for Earth to rotate on its axis. The second way the earth moves is by orbiting, or revolving around, the sun. The path of one object around another object is its orbit.

5. A Year It takes the Earth 365 ¼ days to complete its orbit around the Sun. Every four years, the extra ¼ days add up to one full day. This is called a leap year which is a year that has 366 days. This day is added to the end of February.

6. Earth’s Seasons Seasons occur due to the Earth’s tilt in relation to the sun. Summer: The summer solstice is about June 21. It is the longest day. Autumn: The autumnal equinox occurs around September 21. It has equal parts day and night. Winter: The winter solstice is around December 21. This day has the least amount of daylight. Spring: The spring (vernal) equinox occurs around March 21. The length of day and night are the same.

7. Stars Stars are huge burning balls of superheated gas. A stars color tells us how hot it is. Red stars are cooler and older stars. Blue stars are the hottest. The sun is a medium-size yellow star that is between the hottest and coolest.

8. The Life of a Star

9. The Sun The star at the center of our solar system is called the sun. The sun is made up entirely of plasma, which is super heated gas. It is mostly made of hydrogen. The energy of the sun comes from nuclear fusion reactions that occur deep inside the sun's core. There, hydrogen is fused into helium. Surface features range from relatively cool, dark structures known as sunspots to spectacular eruptions called flares and coronal mass ejections. The sun has 99.8 percent of the mass in the solar system.

10. Lesson 1 Answers The axisis the imaginary line that goes through both poles of a planet on which the Earth spins. The Earth follows its orbit, or path, as it travels around the sun. The seasons change due to the Earth’s tilt. Stars are huge burning balls of gas. The sun is mostly made of hydrogen. Hydrogen is turned into helium in the sun’s core.

11. Space Lesson 2The Earth and the Moon

13. The Moon The moon is a small planet-like body that orbits Earth, rather than the sun. The moon appears to shine, but the light you see is actually reflected from the sun. As the moon orbits Earth, different amounts of its lit surface can be seen. That’s why the moon appears to have different shapes, or phases. The lunar cycle takes 29 ½ days to complete. The full moon phase occurs about 15 days after the new moon phase. The moon has a near side and far side. We always see the near side.

14. Moon Phases New Moon When the Moon is between the Earth and the Sun, it is called the new moon. The new moon rises and sets about the same time as the Sun does, but we can’t see it because the side that is being lit by the Sun is the side we cannot see from Earth. First Quarter After about one week after the new moon, the moon looks like a half-circle, and it is called the first quarter because the moon has completed one-quarter of its orbit around the Earth. Half of the Moon’s sunlit side is now visible from Earth. The first quarter moon rises at about noon and sets at about midnight. Full Moon One week after the first quarter moon, the Moon has moved to a point where the Earth is between the Moon and the Sun. We can now see the entire sunlit side of the Moon. The full moon rises as the Sun sets and sets as the Sun rises. Last Quarter One week after the full moon, the Moon again looks like a half-circle, and it is called the last quarter because the Moon has completed all but the last quarter of its orbit around the Earth. Half of the Moon’s sunlit side is again visible from Earth. The last quarter moon rises at about midnight and sets at about noon.

15. Eclipses A solar eclipse occurs when the moon obscures the sun. It will only occur when the moon is new. A lunar eclipse occurs when the moon crosses through the shadow of the Earth An eclipse does not occur every month because the moon’s orbit isn’t in the same plane as Earth’s orbit of the Sun.

16. Where Did the Moon Come From? The Fission Theory: The Moon was once part of the Earth and somehow separated from the Earth early in the history of the Solar System. The present Pacific Ocean basin is the most popular site for the part of the Earth from which the Moon came. The Capture Theory: The Moon was formed somewhere else, and was later captured by the gravitational field of the Earth. The Condensation Theory: The Moon and the Earth condensed together from the original nebula that formed the Solar System. The Colliding Planetesimals Theory: The interaction of earth-orbiting and Sun-orbiting planetesimals (very large chunks of rocks like asteroids) early in the history of the Solar System led to their breakup. The Moon condensed from this debris. The Ejected Ring Theory: A planetesimal the size of Mars struck the earth, ejecting large volumes of matter. A disk of orbiting material was formed, and this matter eventually condensed to form the Moon in orbit around the Earth.

17. Lesson 2 Answers The moon is a small planet-like body that orbits the Earth. The moon appears to have different shapes, or phases. It takes the moon 29 ½ days to orbit the Earth. The moon has a near side and far side. Identify the following moon phases: New Moon First Quarter Full Moon Last Quarter A solar eclipse occurs when the mooncovers the sun. A lunar eclipse occurs when the moon passes through Earth’s shadow.

18. Space Lesson 3The Solar System

20. Solar Systems A solar system is a group of objects in space that orbit a star in the center, plus the star itself. A planet is a large object that orbits a star. A moon is a smaller object that orbits a planet. Asteroids are bits of rock and metal. Most are less than 1 km across. Most asteroids orbit the sun in a belt between Mars and Jupiter.

21. Comets A comet is a ball of rock, ice, and frozen gases.

23. The Inner Planets The inner planets are those closest to the sun. They are Mercury, Venus, Earth, and Mars. They are alike in many ways. They all have rocky surfaces and are smaller than most of the outer planets. Also, none of the inner planets have more than 2 moons.

25. Mercury orbits the sun at an average distance of about 36 million miles (58 million kilometers), compared with about 93 million miles (150 million kilometers) for Earth.

26. Mercury is difficult to see because it is so close to the sun.

27. Mercury’s surface closely resembles the moon.

28. Mercury is dry, extremely hot, and almost airlessMercury

30. As seen from the Earth, Venus is brighter than any other planet or even any star. When Venus is near its brightest point, it can be seen in daylight.

31. They named Venus in honor of the Roman goddess of love and beauty.

32. Geologists have had difficulty learning about the surface of Venus because the planet is always surrounded by thick clouds of sulfuric acid. They have used radar, radio astronomy equipment, and space probes to "explore" Venus.

33. Until recently, much of what geologists knew about the surface of Venus came from ground-based radar observations, the Soviet Union's Venera space probes, and United States Pioneer probes. In 1990, the U.S. space probe Magellan began orbiting Venus, using radar to map the planet's surface.

35. The Outer Planets The four outer planets are Jupiter, Saturn, Uranus, and Neptune. These planets are huge and made mostly of gases. They all have many moons and are surrounded by rings made of dust, ice or rock.

36. Jupiter Jupiter is the largest planet in the solar system. It would take more than 1,000 Earths to fill up the volume of the giant planet. When viewed from Earth, Jupiter appears brighter than most stars. It is usually the second brightest planet -- after Venus. Jupiter is the fifth planet from the sun. Ancient astronomers named Jupiter after the king of the Roman gods. Jupiter has 16 satellites that measure at least 6 miles (10 kilometers) in diameter. It also has many smaller satellites. Jupiter's four largest satellites, in order of their distance from Jupiter, are Io, Europa, Ganymede, and Callisto. These four moons are called the Galilean satellites. The Italian astronomer Galileo discovered them in 1610 with one of the earliest telescopes. Io has many active volcanoes, which produce gases containing sulfur. The yellow-orange surface of Io probably consists largely of solid sulfur that was deposited by the eruptions. Europa ranks as the smallest of the Galilean satellites. Europahas a smooth, cracked, icy surface. The largest Galilean satellite is Ganymede. Ganymede is larger than the planet Mercury. Callisto, is slightly smaller than Mercury. Ganymede and Callisto appear to consist of ice and some rocky material. The two satellites have many craters. Jupiter has three thin rings around its equator. They are much fainter than the rings of Saturn. Jupiter's rings appear to consist mostly of fine dust particles.

37. Saturn Saturn is the second largest planet. Saturn has seven thin, flat rings around it. The rings consist of numerous narrow ringlets, which are made up of ice particles that travel around the planet. The gleaming rings make Saturn one of the most beautiful objects in the solar system. They named it for the Roman god of agriculture. Saturn travels around the sun in an elliptical (oval-shaped) orbit. The planet takes about 10,759 Earth days, or about 29 1/2 Earth years, to go around the sun, compared with 365 days, or one year, for Earth. In addition to its rings, Saturn has 25 satellites that measure at least 6 miles (10 kilometers) in diameter, and several smaller satellites. The largest of Saturn's satellites, Titan, has a diameter of about 3,200 miles (5,150 kilometers) -- larger than the planets Mercury and Pluto. Titan is one of the few satellites in the solar system known to have an atmosphere. Its atmosphere consists largely of nitrogen. Many of Saturn's satellites have large craters. For example, Mimas has a crater that covers about one-third the diameter of the satellite. Another satellite, Iapetus, has a bright side and a dark side.

38. Uranus Uranus is the seventh planet from the sun. Uranus is the farthest planet that can be seen without a telescope. Uranus is a giant ball of gas and liquid. The surface of Uranus consists of blue-green clouds made up of tiny crystals of methane. The crystals have frozen out of the planet's atmosphere. Uranus was the first planet discovered since ancient times. British astronomer William Herschel discovered it in 1781. Johann E. Bode, a German astronomer, named it Uranus after a sky god in Greek mythology. Most of our information about Uranus comes from the flight of the United States spacecraft Voyager 2. In 1986, that craft flew within about 50,000 miles (80,000 kilometers) of the planet's cloud tops. Uranus is tilted so far on its side that its axis lies nearly level with its path around the sun. Many astronomers think that a collision with an Earth-sized planet may have knocked Uranus on its side soon after it was formed.

39. Neptune cannot be seen without a telescope. Neptune is about 30 times as far from the sun as is Earth. Every 248 years Pluto moves inside Neptune's orbit for about a 20-year period, during which it is closer to the sun than Neptune. Pluto last crossed Neptune's orbit on Jan. 23, 1979, and remained within it until Feb. 11, 1999. Neptune's diameter at the equator is 30,775 miles (49,528 kilometers), or almost 4 times that of Earth. It is about 17 times as massive (heavy) as Earth, but is not so dense as Earth. Neptune has 11 satellites (moons) and several rings around it. Neptune has 11 known satellites. Triton, Neptune's largest satellite. It is the only major satellite in the solar system that orbits in a direction opposite to that of its planet. Triton may once have been a large comet that traveled around the sun. Scientists have discovered evidence that volcanoes on Triton once spewed a slushy mixture of water and ammonia. This mixture is now frozen on Triton's surface. Triton has a surface temperature of -390 degrees F (-235 degrees C), the coldest known temperature in the solar system. Some volcanoes on Triton remain active, shooting crystals of nitrogen ice as high as 6 miles (10 kilometers) above the moon's surface. Neptune

40. Dwarf Planets The dwarf planets - Ceres, Pluto, & Eris Pluto, a Kuiper object, was demoted to the status of dwarf planet in 2006 when the International Astronomical Union (IAU) reviewed Pluto's status in light of the recently discovered Eris, also a Kuiper object, but somewhat larger than Pluto. At the same time the former asteroid Ceres was promoted to dwarf planet. The IAU defines a dwarf plant as a celestial body that, within the Solar System: is in orbit around the Sun; has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (near-spherical) shape; has not cleared the neighborhood around its orbit; and is not a satellite Point 3 is what distinguishes the dwarf planets from the remaining eight planets. In this image, from left to right are the dwarf planets Ceres, Pluto, and Eris. Eris was discovered in 2003 and is now the largest of the known dwarf planets. It is believed to be slightly more massive than Pluto and follows a highly eccentric orbit that alternately brings it as close as the orbits of Neptune and Pluto and as far as over twice Pluto's furthest distance from the Sun.

41. Pluto Pluto, (PLOO toh), is a dwarf planet that orbits far from the sun. It shares the region of its orbit, known as the Kuiper belt, with a collection of similar icy bodies called Kuiper belt objects (KBO’s). From its discovery in 1930, people widely considered Pluto to be the ninth planet of our solar system. However, because of its small size and irregular orbit, many astronomers questioned whether Pluto should be grouped with worlds like Earth and Jupiter. Pluto seemed to share more similarities with KBO’s. In 2006, this debate led the International Astronomical Union, the recognized authority in naming heavenly objects, to formally classify Pluto as a dwarf planet. Pluto cannot be seen without a telescope. As it orbits the sun, Pluto spins on its axis, an imaginary line through its center. It spins around once in about six Earth days. Astronomers know little about Pluto's size or surface conditions because it is so far from Earth. Pluto has an estimated diameter of about 1,400 miles (2,300 kilometers), less than a fifth that of Earth. Pluto's surface is one of the coldest places in our solar system. Astronomers believe the temperature on Pluto may be about –375 °F (–225 °C). Pluto is mostly brown. The planet appears to be partly covered with frozen methane gas and to have a thin atmosphere composed mostly of methane. Because Pluto's density is low, astronomers think Pluto is mainly icy. Scientists doubt Pluto has any form of life. In 1905, Percival Lowell, an American astronomer, found that the force of gravity of some unknown object seemed to be affecting the orbits of Neptune and Uranus. In 1915, he predicted the location of a new planet and began searching for it from his observatory in Flagstaff, Arizona. He used a telescope to photograph the area of the sky where he thought the planet would be found. He died in 1916 without finding it. In 1929, Clyde W. Tombaugh, an assistant at the Lowell Observatory, used predictions made by Lowell and other astronomers and photographed the sky with a more powerful, wide-angle telescope. In 1930, Tombaugh found Pluto's image on three photographs. The planet was named after the Roman god of the dead. The name also honors Percival Lowell, whose initials are the first two letters of Pluto. In 1978, astronomers at the U.S. Naval Observatory substation in Flagstaff detected a satellite of Pluto. They named it Charon.

42. 18. The Inner Planets are made mostly ofrock. 19. The Outer Planets are mostly made of gas. Lesson 3 Answers 14. A solar systemis a group of objects that orbit a star in the center, plus the star itself. 15. A planet is a large object that orbits a star. 16. These mostly lie in an orbit between Mars and Jupiter and are made of rock and metal: asteroids . 17. A comet is a ball of rock, ice, and frozen gases.

43. Space Lesson 4Stars and Galaxies

51. Constellations Constellations are stars that form an imaginary picture in the sky. Constellations in the night sky seem to change position as the Earth revolves around the sun. Due to the Earth’s tilt, different places on Earth see different constellations.

52. Black Holes A black hole is a region of space whose gravitational force is so strong that nothing can escape from it. A black hole is invisible because it even traps light. The descriptions of black holes are based on equations in the theory of general relativity developed by the German-born physicist Albert Einstein. The theory was published in 1916.

53. The Milky Way A galaxy is a huge system of gases, dust and stars. They contain billions of stars. The Milky Way is the galaxy our solar system is located in.

54. Galaxies There are three types of galaxies. Spiral galaxies are shaped like the Milky Way. Elliptical galaxies have very little gas or dust and no stars have recently formed within them. They can range from a near perfect sphere or a flattened disc. Galaxies of a third kind, irregular galaxies, lack a simple shape. Some consist mostly of blue stars and puffy clouds of gas, but little dust. The Magellanic Clouds are irregular galaxies of this type. Others are made up mostly of bright young stars along with gas and dust.

55. Universe The universe is everything that exists in space. Scientists believe the universe is still expanding from the events of the Big Bang. Something unseen appears to be keeping the stars of galaxies from flinging themselves away from the center: unilluminated matter that exerts extra gravitational force. This is dark matter.

56. 20.Constellationsare stars that form an imaginary picture in the sky. 21. Can people in the Southern Hemisphere see the same constellations we see? Why? No because they see a different part of the sky than we do. 22. Why do constellations change as the seasons change? Our orbit around the sun reveals different constellations. A black hole has an intense gravitational pull. A galaxy is a huge system of gases, dust, and stars. 25. The Milky Way is the name of our galaxy. 26. There are three types of galaxies: a spiral b elliptical C irregular 27. The universe is everything that exists in space. Lesson 4 Answers

57. Space Lesson 5The History of Space Exploration

58. Early Models of the Universe In astronomy, the geocentric model or the Ptolemaic worldview of the universe is the theory that the Earth is the center of the universe and other objects go around it. Belief in this system was common in ancient Greece. It was embraced by both Aristotle and Ptolemy, and most, but not all, Ancient Greek philosophers assumed that the Sun, Moon, stars, and naked eye planets circle the Earth. Similar ideas were held in ancient China.

59. Copernicus, Galileo, and Kepler

60. First Satellite and Human in Space On October 4, 1957, the Soviet Union sent Sputnik 1 into orbit. It was the first artificial satellite. On April 12, 1961 the first human to go into space. In the spaceship Vostok 1, Senior Lieutenant Yuri Alexeyevich Gagarin orbited earth one time at an altitude of 187 3/4 miles (302 kilometers) for 108 minutes at 18,000 miles an hour.

61. NASA: Mercury and Gemini The Mercury Project put the first American into space. On June 5, 1961, Alan B. Shepard became the first American in space. John Glenn became the first America to orbit the Earth in 1962. The Gemini program was an important step in preparing to travel to the moon.

62. NASA: Apollo The Apollo missions took man to the moon. On July 20, 1069, Neil Armstrong and Buzz Aldrin became the first men to walk on the moon.

63. NASA: Apollo

64. NASA:The Space Shuttle and the ISS

65. NASA:Moon, Mars, and Beyond

66. NASA:Unmanned Missions

67. Lesson 5 Answers Early models of the universe were geocentric, meaning the Earth was the center of everything. In 1957, Sputnik was the first satellite. Alan Shepardwas the first American in space. Neil Armstrong and Buzz Aldrin were the first humans to walk on the moon. The reusable spacecraft currently in use by NASA is called the space shuttle.