Earth Science Module 2: Our Solar System and Our Universe PDF

Earth Science Module 2: Our Solar System and Our Universe Raymund B. Bolalin DLSU Physics Department Module 2: Learning Outcomes The learners should demonstrate an understanding of: the formation of the universe and the solar system; the geocentric and heliocentric model of the universe;...

Earth Science Module 2: Our Solar System and Our Universe Raymund B. Bolalin DLSU Physics Department Module 2: Learning Outcomes The learners should demonstrate an understanding of: the formation of the universe and the solar system; the geocentric and heliocentric model of the universe; and the contributions of Nicolaus Copernicus, Tycho Brahe, Johannes Kepler, Galileo Galilei, and Isaac Newton to modern astronomy. Module 2: Objectives After this module, the learners should be able to: describe the historical development of theories that explain the origin of the universe; compare the different hypotheses explaining the origin of the solar system; explain the current advancements/ information on the solar system; differentiate the geocentric and heliocentric universe; and list and describe the contributions to modern astronomy of Nicolaus Copernicus, Tycho Brahe, Johannes Kepler, Galileo Galilei, and Isaac Newton. 21.1 Ancient Astronomy Explain the geocentric view of the solar system and describe how it differs from the heliocentric view. Early civilizations, in their pursuit of understanding how the heavens worked, kept records of the positions of celestial objects, believing they were good or bad omens: – Mayans – Chinese – Egyptians – Babylonians – Kubans – Indians – Monotheists  What is cosmology? What is Cosmology? Cosmology is a branch of astronomy that studies the origin of the universe and how it has evolved. Specifically, it is the scientific study of the large scale properties of the universe as a whole – its structure, origin, evolution, and destiny. A branch of physics and metaphysics, it deals with the origin and development of the universe, the cosmos.  Cosmology through the ages… ❑ Long before telescopes and modern astronomy, cultures around the globe were keen observers of the sky, and created maps, metaphors, myths -- all mental models -- for how the heavens worked. MAYANS CHINESE EGYPTIANS Many Mayan buildings 11th Century Chinese Ancient Egyptians were aligned with map of stars in the sky, believed in many gods astronomical events, believed to indicate and myths which narrate such as the solstices and supernova of 1054 that the world arose from equinoxes. an infinite sea at the first rising of the sun.  Cosmology through the ages… ❑ Long before telescopes and modern astronomy, cultures around the globe were keen observers of the sky, and created maps, metaphors, myths -- all mental models -- for how the heavens worked. KUBANS INDIANS MONOTHEISTS The Kuba people of Central In India, there is the narrative The monotheistic religions Africa tell the story of a that gods sacrificed Purusha, of Judaism, Christianity, creator god Mbombo (or the primal man whose head, and Islam claim that a Bumba) who, alone in a dark and water-covered Earth, felt feet, eyes, and mind became supreme being created an intense stomach pain and the sky, earth, sun, and the universe, including then vomited the stars, sun, moon respectively. man and other living and moon. organisms. NON-SCIENTIFIC vs SCIENTIFIC THOUGHTS NON-SCIENTIFIC SCIENTIFIC THOUGHT THOUGHT Nonscientific thought Scientific thought involves involves religions, ethical any ideas about the world beliefs, moral precepts, and which are based on philosophical ideals. inductive reasoning and This can not be observed, which are open to testing measured or predicted. and change. Ancient Astronomy Golden age of Astronomy = Greece (600 B.C.E.–150 C.E.) – Used observational data, as well as geometry and trigonometry Ancient Astronomy Ancient Greeks – Most held geocentric (Earth-centered) view of the universe Earth was a motionless sphere at the center of the universe Stars were on the celestial sphere – Transparent, hollow sphere – Celestial sphere turns daily around Earth Ancient Astronomy Aristotle Ancient Greeks – Aristotle: Earth must be a sphere, because the Earth makes a curved shadow when it eclipses the moon Eratosthenes Aristarchus Hipparchus – Eratosthenes: Calculated Earth’s circumference to within 500 miles of current measurements using the angle of the noonday Sun in two different cities – Aristarchus: Proposed heliocentric (Sun- centered) universe due to geometry of Moon–Earth–Sun relationships – Hipparchus: Mapped stars and calculated a year to within minutes of modern measurements SmartFigure 21.3 Orientation of the Sun’s Rays at Syene and Alexandria, Egypt, on June 21 Ancient Astronomy Ancient Greeks – Ptolemy’s Model of the Universe (141 C.E.): Geocentric Retrograde motion: Appearance that the planets stop and reverse direction for weeks or months To explain retrograde motion, Ptolemy used two motions for the planets – Large orbital circles, called deferents, and – Small circles, called epicycles Claudius Ptolemy Model, though incorrect, predicted motions with accuracy for a century Figure 21.4 The Universe According to Ptolemy Figure 21.4 The Universe According to Ptolemy SmartFigure 21.6 Retrograde Motion of Mars, as Seen Against the Background of Distant Stars 21.2 The Birth of Modern Astronomy List and describe the contributions to modern astronomy of Nicolaus Copernicus, Tycho Brahe, Johannes Kepler, Galileo Galilei, and Isaac Newton. 1500s and 1600s Five noted scientists – Nicolaus Copernicus – Tycho Brahe – Johannes Kepler – Galileo Galilei – Sir Isaac Newton Birth of Modern Astronomy Nicolaus Copernicus (1473–1543) – Concluded Earth was a planet – Constructed a model of the solar system that put the Sun at the center, but he used circular orbits for the planets – Ushered out old astronomy Birth of Modern Astronomy Tycho Brahe (1546–1601) – Precise observer – Tried to find stellar parallax The apparent shift in a star’s position due to the revolution of Earth – Did not believe in the Copernican system because he was unable to observe stellar parallax Birth of Modern Astronomy Johannes Kepler (1571–1630) – Ushered in new astronomy – Planets revolve around the Sun – Three laws of planetary motion Orbits of the planets are elliptical Planets revolve around the Sun at varying speed There is a proportional relation between a planet’s orbital period and its distance to the Sun (measured in astronomical units (AU’s)—one AU averages about 150 million kilometers, or 93 million miles) Figures 21.9 and 21.10 Johannes Kepler and Drawing of Ellipses Figure 21.11 Illustration of Kepler’s Second Law Birth of Modern Astronomy Galileo Galilei (1564–1642) – Supported Copernican theory – Used experimental data – Constructed an astronomical telescope in 1609 Four large moons of Jupiter Planets appeared as disks Phases of Venus Features on the Moon Sunspots Figures 21.12 and 21.13 Galileo and Galilean Telescope SmartFigure 21.15 Using a Telescope, Galileo Discovered That Venus Has Phases Like Earth’s Moon Birth of Modern Astronomy Sir Isaac Newton (1643– 1727) – Law of universal gravitation – Proved that the force of gravity, combined with the tendency of a planet to remain in straight-line motion, results in the elliptical orbits discovered by Kepler 21.3 Patterns in the Night Sky Describe how constellations are used in modern astronomy. Constellations – Configuration of stars named in honor of mythological characters or great heroes – Today 88 constellations are recognized, dividing the sky into units – The brightest stars in a constellation are identified in order of their brightness by the letters of the Greek alphabet—alpha, beta, and so on Figure 21.18 Basic Features of the Celestial Sphere Positions in the Sky Celestial sphere: Stars appear to be fixed on a spherical shell that surrounds Earth – Useful for describing location of objects in the night sky – Measurements using the celestial sphere Direction on the horizon, measured in degrees clockwise from due north Altitude above the horizon, measured in degrees Figure 21.21 The Location of any Object in the Sky Can be Described by Its Altitude and Direction 21.4 The Motions of Earth Describe the two primary motions of Earth and explain the difference between a solar day and a sidereal day. Two primary motions – Rotation (spin) ▪ Mean solar day—the time interval from one noon to the next, about 24 hours ▪ Sidereal day—the time it takes for Earth to make one complete rotation (360°) with respect to a star other than the Sun—23 hours, 56 minutes, 4 seconds Figure 21.23 The Difference Between a Solar Day and a Sidereal Day Earth Motions Two primary motions – Revolution (orbit) Earth’s orbit is elliptical around the Sun – Earth is closest to the Sun (perihelion) in January – Earth is farthest from the Sun (aphelion) in July Ecliptic: The apparent annual path of the Sun against the backdrop of the celestial sphere Earth orbits with the Sun around the galactic center every 230 million years Sketch the changing configuration of the Earth–Moon system that produces the regular cycle we call the phases of the Moon. Moon orbits Earth in an elliptical orbit Synodic month – Cycle of Moon through its phases every 29.5 days – Basis of first Roman calendar – Apparent period of Moon’s revolution around Earth Sidereal month – True period of Moon’s revolution around Earth every 27.3 days Figure 21.24 The Ecliptic and the Plane of the Ecliptic Motions of the Earth–Moon System Lunar motions – Earth–Moon The difference of two days between the synodic and sidereal cycles is due to the Earth–Moon system also moving in an orbit around the Sun – Moon is “tidally locked” by the force of Earth’s gravity over geologic time Period of rotation about its axis and its revolution around Earth are the same, 27 1/3 days Causes the same lunar hemisphere to always face Earth Figure 21.25 The Difference Between a Sidereal Month and a Synodic Month Motions of the Earth–Moon System Phases of the Moon – When viewed from above the North Pole, the Moon orbits Earth in a counterclockwise (eastward) direction – The relative positions of the Sun, Earth, and Moon constantly change – Lunar phases are a consequence of the motion of the Moon and the sunlight that is reflected from its surface SmartFigure 21.26 Phases of the Moon 21.6 Eclipses of the Sun and Moon Sketch the configuration of the Earth–Moon–Sun system that produces a lunar eclipse and the configuration that produces a solar eclipse. Eclipses – Simply shadow effects that were first understood by the early Greeks – Two types of eclipses ▪ Solar eclipse –Moon moves in a line directly between Earth and the Sun –Can only occur during the new-Moon phase SmartFigure 21.27 Solar eclipse Eclipses of the Sun and Moon Lunar eclipse – Moon moves within the shadow of Earth – For any eclipse to take place, the Moon must be in the plane of the ecliptic at the time of new- or full-Moon phase – Because the Moon’s orbit is inclined about 5 degrees to the plane of the ecliptic, during most of the times of new and full Moon the Moon is above or below the plane, and no eclipse can occur – The usual number of eclipses is four per year SmartFigure 21.28 Lunar Eclipse 22.1 Our Solar System: An Overview Describe the formation of the solar system according to the nebular theory. Compare and contrast the terrestrial and Jovian planets. The Sun, 99.5% of the solar system’s mass, is the center of a revolving system consisting of: – Eight planets and their satellites – Smaller bodies ▪ Dwarf planets ▪ Asteroids ▪ Comets ▪ Meteoriods SmartFigure 22.1 Planetary Orbits Our Solar System: An Overview Nebular theory – Describes the formation of solar system – Sun and planets formed from solar nebula Rotating cloud of gas and dust – Solar nebula contracted and formed hot protosun – Planetesimals formed – Planetesimals became protoplanets Our Solar System: An Overview The planets: Internal structures and atmospheres – Two types based on location, size, and density – Terrestrial (Earth-like) – Jovian (Jupiter-like) Terrestrial planets – Mercury, Venus, Earth, and Mars – Small, dense, and rocky – Large cores of iron and nickel – Low escape velocities – Thin atmospheres of carbon dioxide or nitrogen Our Solar System: An Overview Jovian (Jupiter-like) planets – Jupiter, Saturn, Uranus, and Neptune – Large, low density, and gaseous – Massive – Thick atmospheres composed of hydrogen, helium, methane, and ammonia – High escape velocities Figure 22.2 Comparing Internal Structures of the Planets SmartFigure 22.3 Bodies with Atmospheres Versus Airless Bodies Our Solar System: An Overview Impact craters—result from planetary collisions with massive bodies – More common in early history of solar system – Thick atmospheres may cause impacting objects to break up – Craters exhibit central peak and ejecta lands in or near crater Figure 22.4 Formation of an Impact Crater 22.2 Earth’s Moon: A Chip Off the Old Block List and describe the major features of Earth’s Moon and explain how maria basins were formed. Diameter of 3475 kilometers (2160 miles) is unusually large compared to its parent planet Density – 3.3 times that of water – Comparable to Earth’s crustal rocks – Perhaps the Moon has a small iron core Earth’s Moon: A Chip Off the Old Block Gravitational attraction is one-sixth of Earth’s No atmosphere Tectonics no longer active Surface is bombarded by micrometeorites from space which gradually makes the landscape smooth Figure 22.6 Telescopic View of the Lunar Surface Earth’s Moon: A Chip Off the Old Block Earth is too small to have formed with a moon so large A captured object would have an elliptical orbit similar to those around Jovian planets Formed as a result of a collision between a Mars-sized body and semimolten young Earth – Ejected debris was thrown into orbit around Earth – Coalesced to form the Moon Earth’s Moon: A Chip Off the Old Block Lunar surface – Maria (singular, mare), Latin for “sea” Dark regions Fairly smooth lowlands Originated from asteroid impacts and lava flooding the surface Earth’s Moon: A Chip Off the Old Block Highlands – Bright, densely cratered regions – Make up most of the Moon – Make up all of the “back” side of the Moon – Older than maria Craters – Most are produced by an impact from a meteoroid, which produces Ejecta Occasional rays (associated with younger craters) Earth’s Moon: A Chip Off the Old Block Moon evolved in three phases – Original crust (highlands) As Moon formed, its outer shell melted, cooled, solidified, and became the highlands About 4.5 billion years old Excavation of the large impact basins – Between 3.2 and 3.8 billion years old Formation of rayed craters – Material ejected from craters is still visible SmartFigure 22.7 Formation and Filling of Large Impact Basins Earth’s Moon: A Chip Off the Old Block Current surface – Small mass and low gravity = no atmosphere and flowing water – Weathering and erosion are absent – No active tectonics – Micrometeorites continually bombarded – Covered with gray, unconsolidated debris (lunar regolith) 22.3 Terrestrial Planets Outline the principal characteristics of Mercury, Venus, and Mars. Describe their similarities to and differences from Earth. Mercury – Innermost planet – Second smallest planet – No atmosphere – Cratered highlands – Vast, smooth terrains – Very dense – Revolves quickly – Rotates slowly Figure 22.9 Two Views of Mercury Terrestrial Planets Venus – Second to the Moon in brilliance – Similar to Earth in Size Density Location in the solar system – Shrouded in thick clouds Impenetrable by visible light Atmosphere is 97 percent carbon dioxide Surface atmospheric pressure is 90 times that of Earth’s Terrestrial Planets Venus – Surface Mapped by radar Features – 80 percent of surface is subdued plains that are mantled by volcanic flows – Low density of impact craters – Tectonic deformation must have been active during the recent geologic past – Thousands of volcanic structures Figure 22.10 Global View of the Surface of Venus Terrestrial Planets Mars: The red planet – ½ Diameter of Earth – 1 “year” = 687 Earth days – Surface temperatures range from −140°C to 20°C – Thin atmosphere of carbon dioxide (95%) Terrestrial Planets Mars: The red planet – Topography Pitted with impact craters, some imply permafrost beneath Red color due to iron oxide (rust) 2/3 of the surface is heavily cratered highlands, evolved early in planet’s history 1/3 is plains, located in the north, of fluid lava – Possibly the smoothest surface in the solar system – Tharsis bulge: enormous elevated region, appears to have been uplifted and capped with volcanic rock Figure 22.12 Two Hemispheres of Mars Terrestrial Planets Mars – Volcanoes Numerous large volcanoes—largest is Olympus Mons Active as recently as a few million years ago Mantle plumes produced large volumes of lava, but no plate tectonics allowed it to accumulate to make enormous volcanoes – Wind Dominant force Abundant dunes SmartFigure 22.13 Olympus Mons Terrestrial Planets Mars – Water Considerable evidence indicates that liquid water flowed in first billion years of Mars past Carved enormous valleys by catastrophic floods Rounded grains on the surface imply long transport distances Ice is found within 1 meter of the surface Ice caps composed mainly of water ice Recurring slope linnae = streaks appear seasonally on steep, warm Martian slopes, thought to form from briny (salt) water Figure 22.14 Similar Rock Outcrops on Mars and Earth Figure 22.16 Dark Streams on Mars Thought to Be Caused by the Flow of Briny (Salty) Water 22.4 Jovian Planets Summarize and compare the features of Jupiter, Saturn, Uranus, and Neptune, including their ring systems. Jupiter – Largest planet ▪ 2.5 times more massive than combined mass of the planets, satellites, and asteroids ▪ If it had been ten times larger, it would have been a small star ▪ Orbits Sun in 12 Earth years – Rapid rotation ▪ Slightly less than 10 hours ▪ Slightly bulged equatorial region Jovian Planets Jupiter – Banded appearance Multicolored Bands are aligned parallel to Jupiter’s equator Generated by wind systems – Great Red Spot In planet’s southern hemisphere Counterclockwise rotating cyclonic storm Figure 22.17 The Structure of Jupiter’s Atmosphere Jovian Planets Jupiter – Structure Surface thought to be a gigantic ocean of liquid hydrogen Halfway into the interior, pressure causes liquid hydrogen to turn into liquid metallic hydrogen Rocky and metallic material probably exists in a central core – Rings Debris the size of smoke Believed to be due to impacts on moons Amalthea and Thebe Jovian Planets Jupiter – Moons At least 67 moons Four largest moons – Discovered by Galileo in 1610—called Galilean satellites – Io, innermost moon, is most volcanically active in solar system due to tidal pulls – Europa, may have liquid water Eight largest moons appear to have formed as solar system condensed Many small satellites, probably captured objects or remnants of collisions Figure 22.20 Jupiter’s Four Largest moons Jovian Planets Saturn: The elegant planet – Similar to Jupiter in its Atmosphere Composition Internal structure – Moons 62 known moons, varying significantly in size, shape, origin Titan—the largest Saturnian moon (larger than Mercury) Enceladus—erupts fluid ice (cryptovolcanism) Jovian Planets Saturn – Rings Most prominent feature, discovered by Galileo in 1610 Complex Composed of small particles (moonlets) that orbit the planet – Most rings fall into one of two categories based on particle density – Thought to be debris ejected from moons Origin is still being debated Figure 22.22 Saturn’s Major Rings Jovian Planets Uranus – Uranus and Neptune are nearly twins – Rotates “on its side” – Rings – Large moons have varied terrains Figure 22.25 Uranus, Surrounded by Its Major Rings and a Few of Its Known Moons Jovian Planets Neptune – Dynamic atmosphere One of the windiest places in the solar system Great dark spot White, cirrus-like clouds above the main cloud deck – 14 satellites Figure 22.26 Neptune’s Dynamic Atmosphere Jovian Planets Neptune – Triton—largest Neptune moon Orbit is opposite the direction that all the planet’s travel Lowest temperature in the solar system (391°F) Atmosphere of mostly nitrogen with a little methane Volcanic-like activity —cryovolcanism Composed largely of water ice, covered with layers of solid nitrogen and methane Figure 22.27 Triton, Neptune’s Largest Moon 22.5 Small Solar System Bodies List and describe the principal characteristics of the small bodies that inhabit the solar system. Asteroids: Leftover Planetesimals – Most lie between Mars and Jupiter in asteroid belt – Small bodies—largest (Ceres) is about 620 miles in diameter – Some have very eccentric orbits – Many of the recent impacts on the Moon and Earth were collisions with asteroids – Irregular shapes – Recent landings on asteroids, but origin is uncertain Figure 22.28 The Asteroid Belt Small Solar System Bodies Comets: Dirty Snowballs – Leftover material from formation of the solar system – Structure and Composition Nucleus: small central body Rocky and metallic materials Frozen gases vaporize when near the Sun – Produces a glowing head called the coma – Some may develop a tail that points away from Sun due to radiation pressure and the solar wind Figure 22.30 Changing Orientation of a Comet’s Tail as It Orbits the Sun Small Solar System Bodies Comets origin – Kuiper belt: large group of icy objects in outer solar system Pluto lies in Kuiper belt Orbit Sun disc-shaped structure around Sun Leftover planetesimals – Oort cloud: icy planetesimals in spherical shell around outer solar system Random orbits Loosely bound to solar system Figure 22.33 The Realm of the Comets: The Oort Cloud and Kuiper Belt Small Solar System Bodies Meteoroids – Called meteors when they enter Earth’s atmosphere – A meteor shower occurs when Earth encounters a swarm of meteoroids associated with a comet’s path – Meteoroids are referred to as meteorites when they are found on Earth Meteorites: impact Earth’s surface, some make craters SmartFigure 22.35 Meteor Crater, near Winslow, Arizona Small Solar System Bodies Meteorites: Classified by their composition – Irons: mostly iron, 5–20% nickel – Stony: silicate minerals with inclusions of other minerals – Carbonaceous chondrites: contain simple amino acids and other organic material, basic building blocks of life Stony-irons: mixtures – May give an idea as to the composition of Earth’s core – Give an idea as to the age of the solar system SmartFigure 22.34 Iron Meteorite Found near Meteor Crater, Arizona Small Solar System Bodies Dwarf planets – Orbit the Sun – Not the only objects to occupy their area of space – Pluto is the prototype of this new category – Located in the Kuiper belt—a band of icy objects found beyond the orbit of Neptune Small Solar System Bodies Pluto – Not visible with the unaided eye – Discovered in 1930 – Now classified as a dwarf planet – Moon (Charon) discovered in 1978 – Average temperature is −210°C – Recent exploration reveals Pluto is an active body with several distinct terrains Figure 22.36 Images of Pluto Obtained from NASA’s New Horizons Spacecraft Q&A  What are your takeaways from this session? Key Takeaways (1/8) 1. Formation of the Solar System ▪ Nebular Hypothesis: The solar system formed approximately 4.6 billion years ago from a giant cloud of gas and dust known as a solar nebula. Gravity caused the nebula to collapse and form the Sun at its center, with the remaining material coalescing into planets, moons, and other celestial bodies. ▪ Planets and Moons: The solar system consists of eight planets, which are divided into terrestrial planets (Mercury, Venus, Earth, Mars) and gas giants (Jupiter, Saturn) and ice giants (Uranus, Neptune). Many planets have moons, and some, like Jupiter and Saturn, have extensive systems of moons. Key Takeaways (2/8) 2. Earth's Position in the Solar System ▪ Habitable Zone: Earth is located in the habitable zone (or Goldilocks zone) of the solar system, where conditions are just right for liquid water to exist— critical for life as we know it. ▪ Planetary Movement: Earth and other planets orbit the Sun in elliptical paths due to the Sun's gravitational pull. The tilt of Earth’s axis and its revolution around the Sun cause seasonal changes. Key Takeaways (3/8) 3. The Sun: The Star of Our Solar System ▪ Nuclear Fusion: The Sun is a massive ball of hydrogen and helium gases undergoing nuclear fusion, a process that powers the Sun and provides the energy necessary for life on Earth. ▪ Solar Activity: The Sun exhibits solar flares, sunspots, and coronal mass ejections, which can impact Earth’s magnetic field and technological systems. Key Takeaways (4/8) 4. Other Objects in the Solar System ▪ Asteroids, Comets, and Meteoroids: The solar system contains numerous smaller bodies like asteroids (mainly in the asteroid belt between Mars and Jupiter), comets (with long, elliptical orbits), and meteoroids, which sometimes enter Earth's atmosphere as meteors or reach the surface as meteorites. ▪ Dwarf Planets: Pluto, once considered the ninth planet, is now classified as a dwarf planet, along with others like Eris and Ceres.  Key Takeaways (5/8) 5. Beyond the Solar System: Our Place in the Universe ▪ The Milky Way Galaxy: Our solar system is part of the Milky Way, a spiral galaxy that contains billions of stars. Our galaxy is just one of trillions of galaxies in the universe. ▪ The Expanding Universe: According to the Big Bang Theory, the universe began as a singularity around 13.8 billion years ago and has been expanding ever since. Observations of distant galaxies show they are moving away from us, evidence of this expansion. ▪ Dark Matter and Dark Energy: These mysterious components make up most of the universe’s mass and energy, though their exact nature is still not fully understood. Dark matter exerts gravitational forces, while dark energy is responsible for the acceleration of the universe’s expansion. Key Takeaways (6/8) 6. The Search for Extraterrestrial Life ▪ Exoplanets: Advances in technology have allowed astronomers to detect thousands of exoplanets, some of which are in their star's habitable zone, raising the possibility of life beyond Earth. ▪ SETI and Space Exploration: Efforts like the Search for Extraterrestrial Intelligence (SETI) and missions to Mars, Europa, and other celestial bodies are part of humanity’s ongoing quest to find signs of life elsewhere in the universe. Key Takeaways (7/8) 7. Human Exploration and the Future of Space Travel ▪ Manned Space Missions: Human space exploration, from the Apollo moon landings to future missions to Mars, reflects our drive to explore beyond our planet. ▪ Commercial Space Travel: Companies like SpaceX and Blue Origin are working toward making space travel more accessible, potentially leading to space tourism and even colonization of other planets in the future. Key Takeaways (8/8) 8. Cosmology and the Fate of the Universe ▪ The Big Bang and Cosmic Microwave Background: Evidence such as the cosmic microwave background radiation supports the Big Bang Theory. Cosmologists study the universe’s early stages and its eventual fate. ▪ Ultimate Fate: Various theories suggest different outcomes for the universe, such as the "Big Freeze," "Big Crunch," or "Big Rip," depending on how dark energy behaves over time.  Thank you! RAYMUND B. BOLALIN [email protected]