Azumith Observatory Winona Lake, Indiana
A year of sky, every 15 seconds.
Solar Locked
The sun returns to the same point in the sky on different days at different times. Pick those moments and you get a video where the world ages while the light holds still.
How it's made. Each clip pins the sun at one exact spot in the sky: a fixed height and a fixed compass direction. We find every day the sun actually visited that spot, take one matching frame from each, and play them in sequence.
Look for. Snow appearing and melting in the winter clips. The east-at-dawn and west-at-dusk pair lets you compare sunrise and sunset color over the year. Some clips are short, because the sun only reaches certain spots for a few weeks at a time.
Ghostless · Temporal Median
Trees gain leaves and lose them. Snow appears and melts. The lake briefly freezes. Individual clouds, rain showers, and passing birds are filtered away, though a long overcast stretch still reads as a gray sky.
How it's made. Each output frame covers one day. For every pixel, we take the middle value (the median) of roughly 700 photos sampled from the surrounding two weeks, then slide that window forward a day at a time across the year. Anything that moved (clouds, branches, birds) gets filtered out, and anything that stayed put (trees, the dock, the shoreline) survives. The filter has limits: when most of a two-week stretch was overcast, the median sky is overcast too, so cloudy weather lingers even though no single cloud survives.
Look for. The camera's clock overlay dissolves into noise, since each frame blends hundreds of timestamps. The dock and grass slowly accumulate snow, then lose it. The lake's color shifts subtly between seasons.
temporal median · 14-day window · year
Sun Paths
On the four hinge dates of the year (both solstices and both equinoxes) the sun draws its arc across the sky. Side by side, the tilt of the year is visible at a glance.
How it's made. Take one frame every 15 minutes through the day, then stack them into a single image, keeping only the brightest pixel at every spot. The sun is the brightest thing in the sky, so its path across the day gets painted onto the result.
Look for. Winter's arc is shallow and short, while summer's reaches near the top of the frame. The two equinoxes trace nearly identical paths. The bright continuous streaks between suns are the camera's lens flare smearing through the gaps between the 15-minute samples.
Star Trails
Left long enough, the night sky traces arcs around Polaris. Each image is one clear night, 22:00 to 04:00, compressed into a single still.
How it's made. On the year's clearest nights, picked automatically from the cloud-cover index, every frame between 22:00 and 04:00 is stacked into one image that keeps the brightest pixel at each spot. Anything that moved through the sky leaves a trail.
Look for. Polaris is the still point everything else rotates around. Long straight streaks are airplanes, and the fainter slow ones are satellites. The brightest single trail is usually the moon. Each stack covers six hours, so the star arcs sweep about 90 degrees.
Keograms
Every column is a vertical slice of sky from one moment in time. Read left to right, time passes: hour by hour within each day, day by day across the month.
How it's made. From every photo, we pull a single fixed column of pixels, the slice of sky from horizon to top. Then we stack those columns side by side in chronological order. The result is the camera's entire visual history compressed to one image.
Look for. The boundary between dark night and bright day shifts visibly across each monthly strip as sunrise and sunset slide earlier or later. Storms appear as gray vertical streaks. Clear days are smooth top-to-bottom gradients, and cloudy ones are mottled.
Cloud Motion
The 20 hours of the year when the sky changed the most, from fast summer cumulus to frontal lines sweeping across the lake.
How it's made. For every daytime hour, we measure how much each pixel changed over the hour, then average that across the frame. Hours near sunrise and sunset are excluded (the sun has to stay above 15°), since gradual brightness changes would otherwise dominate the score. The 20 highest-scoring hours win.
Look for. August 24, 2025 alone accounts for five of the top 20 hours. Watch for shadow lines sweeping across the lake as fronts roll in, and for summer cumulus building and collapsing.
top 20 hours · stitched montage
Slit Scan
The horizontal axis is time: the left edge is the oldest moment on screen, the right edge the newest. As the video plays, the window slides forward. Older columns fall off the left while newer ones arrive on the right.
How it's made. Each output column is the centre slice of one source photo, sampled roughly every three hours. Stack about 2,400 of those slices left to right and you get one image that spans the year. Animating the window lets you watch the year roll past.
Look for. Every column is a single moment, so day and night alternate as bright and dark stripes. The bright stripes get wider through summer as the days lengthen, then narrow again toward December. Seasonal colour shifts read as broad gradients across the strip.
By the Numbers
A photo every fifteen seconds from May 2025 through April 2026. The numbers below cover the whole index, not just the frames that made it onto this page.
Daily mean