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