* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 19
Copernican heliocentrism wikipedia , lookup
History of astronomy wikipedia , lookup
Outer space wikipedia , lookup
Lunar theory wikipedia , lookup
Aquarius (constellation) wikipedia , lookup
Planets beyond Neptune wikipedia , lookup
Tropical year wikipedia , lookup
IAU definition of planet wikipedia , lookup
Rare Earth hypothesis wikipedia , lookup
Astrobiology wikipedia , lookup
Definition of planet wikipedia , lookup
Astronomical unit wikipedia , lookup
Geocentric model wikipedia , lookup
Solar System wikipedia , lookup
Extraterrestrial skies wikipedia , lookup
Planets in astrology wikipedia , lookup
Planetary habitability wikipedia , lookup
Late Heavy Bombardment wikipedia , lookup
History of Solar System formation and evolution hypotheses wikipedia , lookup
Dialogue Concerning the Two Chief World Systems wikipedia , lookup
Hebrew astronomy wikipedia , lookup
Extraterrestrial life wikipedia , lookup
Formation and evolution of the Solar System wikipedia , lookup
Section 1: Sun, Earth, and Moon Section 2: The Inner and Outer Planets Section 3: Formation of the Solar System Key Terms Planet Solar System Satellite Phase Eclipse The View from Earth If you observe stars on a clear night you may notice that one of the brighter objects changing position and crossing the path of stars. These are planets coming from the Greek word meaning wanderers. A planet is any of the nine primary bodies that orbit the sun: a similar body that orbits another star There are five planets that are visible to the unaided eye: Mercury, Venus, Mars, Jupiter, and Saturn. The sun is our closest star There are billions of stars but the sun is our most important star. Why can’t we see other star during the day? Because the sun makes the daytime sky to bright The sun is an average star of size and temperature Compared to the Earth the sun is 1.4 million km in diameter, about 110 times the diameter of Earth and has a mass 300,000 times the mass of Earth The solar system is the sun, planets, and other objects that orbit the sun. This includes objects of all sizes (large planets, small satellites, asteroids, comets, gas and dust). Everything revolves around the sun The sun is not just the object that all planets orbit, it is also the source of heat and light for the entire system. Many patterns of human life depend on the sun’s cycle. Heat from the sun is a main cause of weather patterns on Earth. Another type of weather, space weather, is caused by energetic particles that leave the sun during solar flares and storms. What can happen during a solar flare? Can zap communication satellites and cause blackouts. Planets and distance stars are visible in the night sky When we pick out the shapes of constellations, we use some of the same patterns the Greeks saw and named. The constellations reminded the Greeks of there myths. By watching the sky for many years , the ancient Greeks calculated that the stars were more distant than the planets were. With the invention of the telescope, people found other objects in the night sky, including many faint stars and three more planets: Uranus, Neptune, and Pluto Earth is a part of a solar system The solar system is the sun and all of the objects that orbit it. The sun is the most important part of our solar system and makes up 99% of the total mass of the solar system and the nine planets make up the last 1%. Gravity holds the solar system together The force of gravity between two objects depends upon their masses and the distance between them. The sun exerts the largest force in the solar system because its mass is so large. What would happen with out the sun’s pull? The planets would fly off into space Gravity is also the force that keeps moons orbiting around planets. Nine planets orbit the sun Why can planets be seen? Because their surface or atmospheres reflect sunlight A planet’s distance from the sun determines how long the planet takes to orbit the sun. Mercury, the closest, takes 88 days to orbit the sun, which is the shortest time of all the planets. Earth takes 365.25 days and Pluto, the most distant planet, takes 248 years or over 90,000 days. A satellite is an object in orbit around a body that has a larger mass. This is why the moon is a satellite to the planet it orbits. Satellites orbit planets All of the planets in our solar system have moons except Mercury and Venus. Currently, we know of 102 natural satellites, or moons, orbiting the planets in our solar system. Thirty-five years ago we only knew of 33. What are the two largest satellites? Jupiter’s Ganymede and Saturn’s Titan. They are larger than the planet Mercury. The Moon The moon’s surface is covered with craters, mostly caused by asteroid collisions early in the history of the solar system. A maria, or large, dark patches on the moon, are seas of lava that flowed out of the moon’s interior and cooled to solid rock. The moon has phases because it orbits Earth Throughout the month the moon has different shapes called phases. The relative position of Earth, the moon, and the sun determine the phases of the moon. There are eight phases of the moon 1. New moon 2. Waxing crescent 3. First quarter 4. Waxing gibbous 5. Full moon 6. Waning gibbous 7. Third quarter 8. Waning crescent The time form one full moon to the next is 29.5 days, or about one calendar month. Phases of the moon are not caused by Earth’s shadow Earth and the moon may seem to make shadows that fall on each other all the time. But Earth, which has a diameter that is four times the diameter of the moon is a distance of 30 Earth-diameters from the moon. Because of this even when the Earth, the moon, and the sun are lined up only a small part of the shadow hits Earth. Eclipses occur when Earth, the moon, and the sun line up Eclipse is an event in which the shadow of one celestial body falls on another. Eclipse can be predicted and can happen when Earth, the sun, and the moon are in a straight line During a new moon, the moon may cast a shadow onto Earth. This is a solar eclipse. When the moon is full, it may pass into the shadow on Earth and this a lunar eclipse Because the moon’s orbit is slightly tilted compared with Earth’s orbit around the sun, the moon is usually slightly above or below the line between Earth and the sun. So, Eclipses are relatively rare. The moon affects Earth’s tides Coastal areas on Earth have two high tides and two low tides each day. Tides are mainly a result of the gravitational influence of the moon. The side of the Earth closest to the moon experiences the strongest gravitational pull. This pull creates a bulge. Because the moon is orbiting Earth as it rotates the times of the tides change throughout the month. When the sun is on the same side of Earth as the moon, the gravitational forces are at their strongest, and tides are at their highest for the month. Key Terms Terrestrial Planets Hydrosphere Asteroid Gas Giant Mercury Best time to see is just before sunrise or just after sunset Covered with craters 0.4 AU from the sun 670K (melt tin) side closest to the sun and 103K side away from the sun. Well below the freezing point of water. 1 day on Mercury equals 58 Earth days 1 year on Mercury is .24 years on Earth No Atmosphere or Water Venus Only seen near sunset or sunrise. Called either the morning star or evening star 0.7 AU from the sun Thick layers of clouds made from carbon dioxide Surface has mountains and plains Spins in the opposite direction of the other planets and sun 1 day on Venus equals 243 Earth days 1 year on Venus is .6 years on Earth Large amounts of sulfuric acid in atmosphere Thick clouds cause a greenhouse affect with temperatures of 700K Earth We measure other planets in relation to Earth 1.0 AU from the sun Only planet known to sustain life Contains large amounts of liquid water All water on Earth’s surface both liquid and frozen is called the hydrosphere The hydrosphere moderates the temperature on Earth Atmosphere is composed of 78% Nitrogen, 21% Oxygen, 1% Carbon dioxide and other gases Atmosphere also moderates temperatures and protects us from some harmful ultraviolet radiation and space debris Mars Polar ice cap composed of carbon dioxide and small amounts of water Thin atmosphere composed of carbon dioxide 1.5 AU from the sun Two small satellites Phobos and Deimos 10% of Earth’s mass 1 day on Mars equals 24.6 Earth hours 1 year on Mars is 1.9 Earth years Very cold 144K to 300K Largest volcanoes in solar system Martian volcanoes. Olympus Mons largest mountain in solar system Looks red because of Iron oxide Large dust storm on the surface Terrestrial planets are the highly dense planets near the sun. They are small and have solid rocky surfaces. Astronomical Unit (AU) is the distance from the Earth to the sun. 1 AU equals 150 million km Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto = 0.4 = 0.7 = 1.0 = 1.5 = 5.2 = 9.6 = 19.2 = 30.0 = 39.0 The surface temperature of Venus is hotter than Mercury’s surface because of the amount of atmosphere which cause a greenhouse effect. Mercury does not have an atmosphere to trap the radiation from the sun. This causes the temperature on Mercury to vary during the day and at night. However on Venus, the atmosphere is so thick that it causes what is known as the runaway greenhouse effect. This means that the more heat is built up the more efficient the atmosphere becomes at trapping radiation. Olympus Mons is part of the Martian volcanoes. It is the largest mountain in our solar system. It is three times the height of Mount Everest. The Martian volcanoes grew from lava flows. Because Mars has low gravity, the weight or the lava is lower than on other planet, volcanoes could grow very large. Asteroid Belt Between Mars and Jupiter lies hundreds of small rocky objects that range in diameter from 3km to 700 km. They are called asteroids. When they enter the Earth’s atmosphere and burn up they are called meteors. If they hit the Earth’s surface which is very rare, they are called meteorites. Jupiter Largest planet in the solar system Large enough to hold 1300 Earths 80 time more massive could be a star 5.0AU from the sun Takes 12 Earth years to orbit the sun Rotates once around its axis in less than 10 hrs Atmosphere contains hydrogen, helium, methane, and ammonia Appears to have jet streams and huge storms Great Red Spot huge hurricane that is over twice the diameter of Earth Has 39 satellites Four largest satellites are Io, Europe, Ganymede, and Callisto Io has a thin atmosphere and active volcanoes Europe may have liquid water under its icy surface Saturn 95 times the mass of Earth 29 years to orbit the sun and rotates on its axis every 10.7 hours Has a system of rings made of dust, rock, and ice Has 30 satellites May still be forming Radiates three times more energy than it receives from the sun Uranus Bluish in color because of the methane Atmosphere composed of hydrogen, helium, and methane Discovered by accident 14 times the mass of Earth 19.2 AU from the sun and takes 84 years to orbit the sun Rotates every 17 hours but on its side (98) Has the most extreme seasons with wind speeds of 200-500km/h Neptune Bluish in color because of the methane Atmosphere composed of hydrogen, helium, and methane Discovered after Uranus by Johann Galle 17 times the mass of Earth 30 AU from the sun and takes 164 years to orbit the sun Rotates every 16 hours Has a storm system similar to Jupiter Pluto Has one satellite Charon Thin gaseous atmosphere with a solid icy surface Orbits the sun in a long ellipse Averages distance from the sun is 40AU Take 248 years to orbit the sun Is .002 the mass of Earth The outer planets are much larger than the inner planets and have thick gaseous atmospheres, many satellites and rings. They are known as the gas giants Space missions to outer planets include Pioneer launched in 1972 and 1973 Voyager 1 and 2 launched in 1977 Galileo spacecraft launched in 1989. Flew to the large outer planets and dropped a probe into Jupiter’s atmosphere in 1995 New Horizon is planned to investigate Pluto before 2020 Scientist believe that the rings around Saturn may have formed two different ways. The way is by a smashed satellite. The second way that the rings may have formed is by leftover material when Saturn and its satellites formed. Scientist believe that helium in Saturn’s outer layer is condensing and falling inward. As the helium nears the central core it heats up. When Saturn uses up its helium, this process will stop and Saturn will reach a state of equilibrium Key Terms Nebula Nebular Model Accretion Comet Astronomy - The Original Science Ptolemy expanded on the geocentric “Earthcentered” model of Aristotle. He thought that the sun, moon, and planets orbited Earth in perfect circles. His theory described what we see in day-to-day life, including motions of the sun and planets. His model was used for over a thousand years. Copernicus proposed a heliocentric “sun-centered” model of the solar system. Where Earth and the other planets orbited the sun in perfect circles. Kepler improved on Copernicus model by proposing that the orbit of the planets around the sun are ellipses, or ovals, rather than circles. Newton explained that the forces that keeps the planets in orbit around the sun and satellites in orbit around planets is gravity. His theory also stated that every object in the universe exerts a gravitational force on every other object. The Nebular Model According to dating rocks, scientist believe the solar system is approximately 4.6 billion years old. Why are planets so far away from each other? Why are they almost in the same plane? Why are their orbits nearly circular? Why do they orbit in the same direction? Why are the terrestrial planets different from the gas giants? A nebula is a large cloud of dust and gas in space The most widely accepted model of the formation of the solar system is the nebular model. According to the nebular model, the sun, like every star formed from a cloud of gas and dust that collapsed because of gravity. The planets formed by the accretion of matter in the disk. The nebular theory explains why terrestrial planets are different from the gas giants. It also explains smaller rocks in space. Rocks in Space Asteroids can be found between Mars and Jupiter. Meteoroids are small pieces of rock that enter Earth’s atmosphere. Most meteoroids burn up in the atmosphere, and we see them as meteors streaking through the night sky. If a meteoroids survive the atmosphere and hit the ground, it is called a meteorite. A comet is a small body of ice, rock, and cosmic dust loosely packed together that follows an elliptical orbit that gives off gas and dust in the form of a tail as it passes close to the sun. By studying comets, scientist have gained important information about the material that made the solar system. Comets come from the Kuiper belt, a disk-shaped region beyond the orbit of Neptune, and the Oort cloud, a spherical region in the outer solar system beyond the orbit of Pluto. Halley’s comet is one of the most famous comets. it appears in Earth’s sky once every 76 years. Asteroids can be made of many different elements. There are three major types of asteroids. 1. 2. 3. Stony meteorites include carbon-rich specimens that contain organic material and water. Metallic meteorites are made of iron and nickel. Stony-iron meteorites are a combination of the two types. Most meteorites that have been collected are stony and have compositions like those of the inner planets and the moon. How the Moon Formed There are several theories for how the moon formed. Some Thought a separate body was captured by Earth’s gravity. Others thought the moon formed at the same time as Earth. When Earth was still forming it was molten, or heated to an almost liquid state. A Mar-sized body struck Earth at an angle and was deflected. At impact, a large part of the Earth’s mantle was blasted into space. Other Stars Have Planets Astronomers have discovered over 90 planets by measuring the small gravitational effects they have on their parent stars. As a planet orbits its star, it cause the star to wobble back and forth.