Stars and Brightness — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. According to the passage, why did ancient people first track the positions of stars?
A) To predict seasons, plant crops, and navigate at sea
B) To measure the exact mass of distant galaxies
C) To send radio signals to nearby planets in orbit
D) To calculate the energy released by supernova explosions
Early people used star patterns to time planting, mark seasons, and steer ships before maps and clocks.
2. What new tool did Galileo use in the early 1600s to study the night sky?
A) A modern radio dish
B) An early refracting telescope
C) A space-based infrared camera
D) A computer-controlled mirror array
Galileo improved an early refracting telescope and used it to discover Jupiter's moons and lunar craters.
3. Which discovery from Galileo's observations changed views of the solar system most?
A) The Sun is exactly the size of Earth
B) Stars are smaller than nearby planets
C) Jupiter has its own orbiting moons
D) The Moon emits its own bright light
Seeing moons orbit Jupiter showed that not everything circles Earth, supporting a Sun-centered model.
4. How do modern astronomers extend what Galileo started?
A) By staring at the Sun without protective filters
B) By guessing star distances from feelings rather than data
C) By giving up telescopes for unaided eye observations
D) By using space telescopes that detect many wavelengths of light
Modern space telescopes capture infrared, ultraviolet, X-ray, and visible light, far beyond Galileo's tools.
Part B: Fill in the Blank
Write the correct answer on each line.
1. Ancient astronomers used star patterns to mark the changing seasons of the year.
Early calendars relied on star and Sun positions to mark the start of each season.
2. Galileo used a telescope to look more closely at the Moon, Jupiter, and the Milky Way.
Galileo's telescope revealed details invisible to the naked eye, transforming astronomy forever.
3. When Galileo saw four points of light circling Jupiter, he realized they were Jupiter's moons.
Galileo identified Io, Europa, Ganymede, and Callisto as moons orbiting Jupiter, not Earth.
4. Modern astronomers place some telescopes in space to avoid blur from Earth's atmosphere.
Above the atmosphere, telescopes get sharper images and can detect light blocked at ground level.
5. Studying the sky over time helps scientists understand how stars are born and how they change.
Long-term observations reveal how stars form, evolve, and end their lives across cosmic time.