Ancient Star Gazers
This ancient Greek philosopher believed Earth was at the center of the universe surrounded by 55 crystalline spheres.
Who is Aristotle?
Copernicus published his famous book proposing a heliocentric universe while on this uncomfortable occasion.
What is his deathbed?
Kepler’s First Law states that planets do not orbit in perfect circles, but in this stretched-out oval shape.
What is an ellipse?
This is the standard unit of measurement used by scientists to measure mass in physics and astronomy calculations.
What are kilograms (kg)?
Sun, Moon, and stars appear to rise in the east and set in the west every day because of this movement of Earth.
What is Earth's rotation on its axis?
Long before Copernicus, this ancient Greek was the first to suggest a heliocentric model because he realized the Sun was much bigger than Earth.
Who is Aristarchus?
Before the telescope was even invented, this Danish astronomer collected super accurate planetary data using massive instruments.
Who is Tycho Brahe?
According to Kepler's 1st Law, this object sits at one of the focus points of a planet's elliptical orbit.
What is the Sun?
While mass is the amount of "stuff" in an object (in kg), this is the gravitational pull on that mass measured in Newtons.
What is weight (or FG)?
This term describes the apparent backward motion of planets moving east-to-west across the night sky.
What is retrograde motion?
To save the geocentric model, Ptolemy used these small circular orbits riding along larger orbital paths to explain retrograde motion.
What are epicycles?
Galileo was the first to use a telescope for astronomy, but he didn't write his findings in Latin—he published them in this everyday language.
What is Italian?
If an orbit has an eccentricity of 0, it forms this exact geometric shape.
What is a perfect circle?
"For every action, there is an equal and opposite reaction" is the common phrase for this law of motion.
What is Newton's 3rd Law?
In a heliocentric system, planets don't actually turn around and move backward. Retrograde motion is just an optical illusion caused when Earth does this in its orbit.
What is passes (or laps) a slower-moving outer planet?
This term describes an object's ability to reflect light. Planets don't make their own light; they rely on this!
What is albedo?
Galileo discovered four large moons orbiting this giant gas planet, proving not everything revolves around Earth.
What is Jupiter?
According to Kepler’s 2nd Law (Law of Equal Areas), a planet moves the fastest when it is at this point in its orbit.
What is closest to the Sun?
In Newton's Universal Gravitation equation, all distance (d) between two objects must be measured from this specific spot.
What is the center of mass?
Galileo observed that this planet goes through a complete set of phases like our Moon, proving it must orbit the Sun.
What is Venus?
This is the scientific definition of a theory. It’s not just a guess—it explains this about the natural world.
What is WHY or HOW something happens?
Isaac Newton invented this type of telescope that uses mirrors instead of glass lenses to get a clearer picture.
What is a reflecting telescope?
According to Kepler’s 3rd Law, Planet X (100 million km from the Sun) will have a shorter or longer year than Planet Y (500 million km away)?
What is shorter?
If you keep the mass of two objects the same but move them farther apart, the gravitational force between them will do this.
What is decrease?
Stars can change in brightness because they physically expand/contract, but planets change brightness mostly because of this changing variable.
What is their distance from Earth (or reflection angle/albedo)?