The two clocks behind sunrise and sunset: solstices, tilt and latitude
Change date, latitude and axial tilt to see how day length and solar noon set sunrise and sunset—and why their four extremes miss the solstices.
Why does sunset change time? Why does the Moon change shape? Start with things you can see, then follow the links between light, position and motion. Most lessons include interactive diagrams: change a condition, compare the result and read what causes it.
Choose a familiar phenomenon and try its diagram. Each lesson stands on its own; there is no required order.
Change date, latitude and axial tilt to see how day length and solar noon set sunrise and sunset—and why their four extremes miss the solstices.
Move the Moon and compare sunlight in space, the disk seen from Earth, and approximate viewing times.
Scrub through time and draw the loop Mars traces backwards across the stars yourself.
Earth’s tilt sets sunrise and sunset, the air sets the sky’s colour, and auroras and meteors glow about 100 km up.
Change date, latitude and axial tilt to see how day length and solar noon set sunrise and sunset—and why their four extremes miss the solstices.
Turn your view and lower the Sun to explore blue sky, warm sunlight and high clouds after sunset. Learn Rayleigh and Mie scattering, optical depth and twilight.
Follow the chain from sunspots and CMEs to the auroral oval, then use it to plan a realistic aurora trip.
Textbooks say meteors burn from friction with the air. That sentence points at the wrong heat source. Drag altitude, speed and size, and see what is doing the heating.
Phases, eclipses and tides all follow from where the Sun, Earth and Moon sit; calendars turn the Moon’s cycle into dates.
Move the Moon and compare sunlight in space, the disk seen from Earth, and approximate viewing times.
Use a nineteen-year timeline to compare solar, lunar and lunisolar calendars, see months drift against the seasons, and examine how principal solar terms guide leap-month placement.
The Moon's orbit leans 5.16 degrees, so most new and full moons do nothing at all. Turn the nodes and build a total eclipse, a ring, and a blood moon yourself.
Move the Moon, follow the change in tidal range, and learn where an astronomical model ends and a harbour forecast begins.
Try no spin, half speed, and synchronous rotation to see why one spin per orbit is the only setting that keeps one lunar face aimed at Earth.
Planets seen from a moving Earth: retrograde loops, oppositions, elongations, and the epicycles once used to describe the same motion.
Scrub through time and draw the loop Mars traces backwards across the stars yourself.
Use elongation to tell when a planet is visible all night or close to the Sun, and compare different Mars oppositions.
Why the two inner planets are always twilight objects, and why Venus is brightest as a crescent.
One geometry, two choices of origin. Move the origin and the epicycles appear on their own.
Step outside Earth’s viewpoint and see the whole disc: planetary orbits, comets, points of gravitational balance, and the slow turning of an orbit itself.
All eight planets on the ecliptic plane at true scale and true period, with free zoom and a speed ladder.
The solar system is a disc. Seen from the side it is a line, which is why the diagram has to say how much it is exaggerating.
Move perihelion and aphelion to explain the coma, two tails, high eccentricity, and SL9's impact on Jupiter.
Start with Webb, Roman and Gundam, then operate Sun–Earth and Earth–Moon models to find five fixed locations.
The orbit itself turns. Watch the long axis sweep a few degrees over six thousand years, and meet Mercury's extra 43 arcseconds.
Read the whole sky from the ground: star-map directions, magnitude and light pollution, where astronomy and astrology part ways, and when and where to find the centre of the Milky Way.
Drag a real star chart to find your bearings, then hold your view steady while time and month change.
Change sky background and limiting magnitude over one fixed Orion field, then compare Bortle, SQM, VIIRS, and international dark-sky designations.
Turn one ecliptic dial, then use Sirius, ancient calendars, and two studies to trace the line between observation, interpretation, and prediction.
Pick a city and a date, find the galactic centre on a real star chart, then see how the hour, month and latitude change its overlap with darkness.
Choose everyday explanations for the main idea or a deep dive for definitions and model details. Tap or focus underlined terms for their meaning. Sources and model limits are listed in each lesson.
Start with sunrise and sunset or Moon phases for a familiar example, or retrograde motion for planets. Each lesson stands alone; related links suggest the next step.
Most diagrams calculate from the conditions you choose. Data, approximations and scale vary by lesson; check its model notes.
These diagrams explain phenomena. For real observations, check the date, location, weather and tool limits; not every diagram is a precision ephemeris or finder chart.
Related tools: Sky Map · Astronomy Calendar · Moon Phases