Unit E Science Exam Study
🔭 1. Geocentric vs. Heliocentric Models
• Geocentric: Earth at the center (supported by Aristotle).
• Heliocentric: Sun at the center (proposed by Copernicus, supported by Galileo and Kepler).
👨🔬 2. Key Scientists
• Aristotle: Believed in geocentric universe.
• Copernicus: Proposed heliocentric model.
• Galileo: Used telescope, observed moons of Jupiter → proved heliocentric model.
• Kepler: Discovered orbits are elliptical, not circular.
🌀 3. Ellipse & Ecliptic
• Ellipse: Oval shape of planetary orbits.
• Ecliptic: The Sun’s apparent path through the sky over the year.
🌞🌍 4. Equinox vs. Solstice
• Equinox: Equal day and night (spring & fall).
• Solstice: Longest and shortest days (summer = longest, winter = shortest).
☀ 5. Solar Winds
• Stream of charged particles from the Sun.
• Protected by: Earth’s magnetic field and atmosphere.
🧮 6. Astronomical Unit (AU)
• 1 AU = 149,599,000 km → Distance from Earth to Sun.
🌌 7. Celestial Objects
• Stars: Glowing spheres of gas.
• Constellations: Patterns of stars.
• Galaxy: Group of stars, gas, dust held by gravity (e.g., Milky Way).
• Solar System: Sun + planets + moons + other objects orbiting it.
⭐ 8. Life Cycle of a Star
• Nebula → Protostar → Main Sequence → Red Giant → Supernova → Neutron Star / Black Hole.
📊 9. Hertzsprung-Russell Diagram
• Graphs stars by brightness (luminosity) vs. temperature (color).
🪐 10. Inner vs Outer Planets
• Inner (Terrestrial): Mercury, Venus, Earth, Mars — small, rocky.
• Outer (Jovian): Jupiter, Saturn, Uranus, Neptune — large, gaseous.
🌠 11. Light-Year
• Distance light travels in a year = 9.5 trillion km.
🧭 12. Azimuth & Altitude
• Azimuth: Compass direction (N = 0°, E = 90°, S = 180°, W = 270°).
• Altitude: Angle above the horizon (0° = horizon, 90° = overhead).
☄ 13. Space Rocks
• Asteroid: Rock in space (main belt between Mars & Jupiter).
• Comet: “Dirty snowball,” ice and dust, has a tail.
• Meteoroid: Small rock in space.
• Meteor: Meteoroid burns in Earth’s atmosphere.
• Meteorite: Lands on Earth.
🚀 14. Space Technology
• Space shuttle: Reusable spacecraft.
• Space probe: Unmanned; collects data (e.g., planet atmospheres).
• Space station: Human habitat for long missions (e.g., ISS).
💨 15. Rocket Propulsion
• Rockets use Newton’s 3rd Law: For every action, there’s an equal and opposite reaction.
• Burn fuel → gas pushed out → rocket moves up.
🛰 16. Launch Milestones
• Sputnik (1957): First artificial satellite (USSR).
• Anik 1 (1972): Canadian communications satellite.
• ISS (1998+): International Space Station launched and assembled in stages.
🪐 17. Gravity & Microgravity
• Gravity: Force pulling objects toward each other.
• Microgravity: Very weak gravity in orbit → bones weaken, muscles shrink, fluids shift.
🌐 18. Satellites & Remote Sensing
• Satellites: Orbit Earth; used for weather, communication, GPS.
• Remote sensing: Observing Earth without direct contact (e.g., weather, land use).
📍 19. GPS
• Uses satellites to pinpoint location on Earth using triangulation.
🔭 20. Telescopes
• Optical:
• Refracting: Uses lenses.
• Reflecting: Uses mirrors → clearer images.
• Radio:
• Uses radio waves.
• Works in any weather/day or night.
🌌 21. Hubble Space Telescope
• Launched in 1990.
• Orbits Earth, takes clear images (above the atmosphere).
🌈 22. Spectroscope
• Analyzes light spectrum from stars → determines elements in stars.
📐 23. Triangulation
• Measure angles from 2 points to find distance.
• Wider baseline = more accuracy.
👨🚀 24. Space Suits
• Provide:
• Oxygen
• Pressure
• Temperature control
• Protection from radiation
♻ 25. Space Junk
• Debris from satellites, rockets.
• Risks: Damage to spacecraft and satellites.
👀 26. Parallax
• Object appears to shift position when viewed from different places.
• Used to measure distances to nearby stars.
🛰 27. Pros and Cons of Space Exploration
Pros:
• New tech (GPS, materials)
• Scientific knowledge
• Global cooperation
Cons:
• High cost
• Space junk
• Risks to astronauts