Sky and Stars
This 23.5° angle of the Earth’s axis is the reason we experience seasons.
What is the tilt of the Earth?
This is the scientific study of space, planets, and stars — not to be confused with astrology.
What is astronomy?
The iron in our blood and calcium in our bones come from this cosmic event.
What are exploding stars (supernovae)?
The astronomer who first proposed that the Sun, not Earth, was at the center of the solar system.
Who was Copernicus?
The galaxy we live in, home to billions of stars and a central black hole.
What is the Milky Way?
The apparent yearly path of the Sun through the constellations marks this line in the sky.
What is the ecliptic?
This false model placed Earth at the center of the universe.
What is geocentrism?
The total of everything that exists and can be observed.
What is the universe?
He improved the telescope, observed Jupiter’s moons, and supported heliocentrism.
Who was Galileo?
This percentage of the universe can be directly seen or measured.
What is about 4 percent?
The constellations the Sun passes through along the ecliptic form this well-known group.
What is the zodiac?
Planets don’t twinkle like stars because they appear this way in the sky.
What is closer to Earth?
Each galaxy contains many of these systems.
What are solar systems?
This famous Greek philosopher first established the influential geocentric model.
Who is Aristotle?
Despite its vastness, most of the universe — and even solid matter — is made mostly of this.
What is empty space?
As Earth orbits the Sun, this is why different constellations appear after sunset at different times of year.
What is our changing viewpoint from Earth’s orbit?
Streetlights and city glow cause this, making fainter stars hard to see.
What is light pollution?
The nearest large galaxy to ours.
What is Andromeda?
He invented calculus and used physics to explain how gravity controls planetary motion.
Who was Isaac Newton?
The invisible substance known only by its gravitational effects.
What is dark matter?
This slow “wobble” of Earth’s axis, taking 26,000 years, changes which star appears at the North Celestial Pole.
What is precession?
The star that appears fixed above the North Pole and helps travelers find direction
What is Polaris?
The brightest, most energetic regions at galaxy centers powered by black holes.
What are quasars?
Who was Hipparchus?
He catalogued the stars and developed a system to measure their brightness.
The universe is expanding faster today than yesterday due to this mysterious force.
What is dark energy?