Astrophysics & Modern Cosmology 2026 Study Guide

1. What is the currently accepted age of the universe according to the ΛCDM model (as of 2026)? A) 10.5 billion years B) 13.8 billion years C) 15.2 billion years D) 20 billion years Correct Answer: B) 13.8 billion years 2. Which force is primarily responsible for the "accelerated expansion" of the universe? A) Gravity B) Dark Energy C) The Strong Nuclear Force D) Electromagnetism Correct Answer: B) Dark Energy 3. What percentage of the universe's mass-energy content is estimated to be "Dark Matter" and "Dark Energy"? A) 25% Dark Matter, 70% Dark Energy B) 50% Dark Matter, 50% Dark Energy C) 10% Dark Matter, 90% Dark Energy D) 95% Dark Matter, 5% Dark Energy Correct Answer: A) 25% Dark Matter, 70% Dark Energy 4. What is the "Hubble Tension"? A) The friction between galaxies in a cluster B) The statistically significant discrepancy between the expansion rate of the universe measured via the CMB vs. local supernovae C) The tension on the space-time fabric near a black hole D) The slowing down of cosmic expansion Correct Answer: B) The statistically significant discrepancy between the expansion rate of the universe measured via the CMB vs. local supernovae 5. What are "Gravitational Waves"? A) Light waves emanating from a supernova B) Ripples in the fabric of spacetime caused by the acceleration of massive objects (like merging black holes) C) Sound waves traveling through the vacuum of space D) Particles emitted by the sun Correct Answer: B) Ripples in the fabric of spacetime caused by the acceleration of massive objects (like merging black holes) 6. Which instrument is primarily used to detect gravitational waves on Earth? A) The James Webb Space Telescope B) LIGO (Laser Interferometer Gravitational-Wave Observatory) C) The Hubble Space Telescope D) Particle accelerators Correct Answer: B) LIGO (Laser Interferometer Gravitational-Wave Observatory) 7. What is a "Black Hole's Event Horizon"? A) The center of the black hole B) The boundary beyond which nothing, not even light, can escape C) The accretion disk surrounding the hole D) The region where time stops completely Correct Answer: B) The boundary beyond which nothing, not even light, can escape 8. According to General Relativity, gravity is: A) A force that pulls objects together B) The curvature of spacetime caused by mass and energy C) A form of electromagnetic radiation D) A particle called a graviton Correct Answer: B) The curvature of spacetime caused by mass and energy 9. What does "Redshift" indicate in cosmology? A) An object is getting hotter B) An object is moving away from the observer, stretching the wavelength of emitted light C) An object is moving closer to the observer D) The object is about to explode Correct Answer: B) An object is moving away from the observer, stretching the wavelength of emitted light 10. What is the "Cosmic Microwave Background" (CMB)? A) The light from the first stars B) The leftover radiation (heat) from the Big Bang C) Noise from modern radio stations D) Light reflected by space dust Correct Answer: B) The leftover radiation from the Big Bang 11. Which telescope, active in 2026, specializes in infrared observations of the early universe? A) Hubble B) James Webb Space Telescope (JWST) C) Chandra X-ray Observatory D) Kepler Correct Answer: B) James Webb Space Telescope (JWST) 12. "Stellar Nucleosynthesis" is the process by which: A) Planets are formed B) Heavier elements are created through nuclear fusion in the cores of stars C) Stars die and collapse D) Black holes are formed Correct Answer: B) Heavier elements are created through nuclear fusion in the cores of stars 13. A "Supernova" is: A) A star that is slightly larger than the sun B) The massive, powerful explosion of a dying star C) A planet orbiting a black hole D) A comet passing close to Earth Correct Answer: B) The massive, powerful explosion of a dying star 14. What are "Exoplanets"? A) Planets located in our solar system B) Planets orbiting stars outside our solar system C) Planets that have left their orbits D) Asteroids in the Kuiper Belt Correct Answer: B) Planets orbiting stars outside our solar system 15. What is the "Habitable Zone" (Goldilocks Zone)? A) The center of the galaxy B) The orbital region around a star where conditions might be just right for liquid water to exist on a planet's surface C) The zone between two galaxies D) The area where planets never collide Correct Answer: B) The orbital region around a star where conditions might be just right for liquid water to exist 16. "Dark Matter" is inferred primarily because: A) It blocks all light B) Galaxies rotate faster than expected based on visible matter alone, implying unseen mass C) It emits radio waves D) It is visible in X-ray telescopes Correct Answer: B) Galaxies rotate faster than expected based on visible matter alone, implying unseen mass 17. What is "Inflation" in the early universe? A) The slow cooling of the universe B) A period of extremely rapid exponential expansion in the first fraction of a second after the Big Bang C) The formation of the first black holes D) The expansion of galaxies toward each other Correct Answer: B) A period of extremely rapid exponential expansion in the first fraction of a second after the Big Bang 18. What is a "Quasar"? A) A small, cold star B) A supermassive black hole at the center of a distant galaxy, actively accreting matter and emitting massive amounts of energy C) A cluster of planets D) A dark matter cloud Correct Answer: B) A supermassive black hole at the center of a distant galaxy, actively accreting matter and emitting massive amounts of energy