Bibliography
Check the pages behind a claim.
Open the Wikipedia page for a claim you just saw. Each exhibit’s claims sit under its name.
Your Sky
Zoom from street to Moon–Earth–Sun geometry.
Phase is how much of the always-sunlit half faces you; new Moon hides near the Sun.
Story
Ancient people watched the sky to make calendars.
Planets are the wanderers among the fixed stars.
Eratosthenes measured Earth’s circumference from shadows.
Geocentrism with epicycles was believable and predictive for centuries.
Heliocentrism explains retrograde motion as an overtaking pass.
Venus runs through a full set of phases, which Ptolemy's arrangement cannot produce.
Orbits are ellipses with equal areas in equal times.
One inverse-square law unites falling apples and orbiting moons.
Light moves at a finite speed, and that same finite speed is what finally caught Earth moving.
The Sun lies in the Milky Way’s Orion Arm.
Solar System
A birth sign names the Sun’s place in the zodiac on your birth date.
A shooting star is the streak of light made by a meteoroid.
Eclipses occur near the Moon’s crossings of the Sun’s path.
Earth’s rotation makes the sky appear to turn each day.
Earth’s tilt changes the Sun’s path across the sky over the year.
Real eclipse dates at true scale: the umbra is a needle, and where it lands is the only place the Sun goes out.
Earth’s 23.44° tilt produces the seasons.
Stars hidden by sunlight return to the night sky as Earth moves around the Sun.
Plotting the Sun at the same time each day draws an analemma.
Sunrise happens as Earth turns your place toward the Sun.
The ecliptic marks the plane of Earth’s orbit.
Named showers return yearly when Earth crosses dust trails.
Orbits
Kepler tested a circle against Tycho's Mars observations and found it off by eight arcminutes.
Planets farther from the Sun take longer to complete an orbit.
Navigate
The angle from the horizon to the sky’s turning point gives your latitude.
A one-hour difference between local solar times equals 15° of longitude.
At sea, an accurate clock kept Greenwich time so navigators could find longitude.
A sextant measures the angle between the horizon and an object in the sky.
The Story room puts these ideas in the order people found them.
Go to the Story