"Put the staff in a certain place at the right time, and it will give you the exact location of the Well of Souls."
To track down a secret site or object, characters must observe a beam of sunshine or moonlight, or a shadow cast by such light, which indicates its location. Often this is only possible at a specific time of day and year, although this limitation may be ignored for plot convenience. That said, the idea that you have to race to get the right Plot Coupon to the right place at the right time (which will always be really soon after you find it) makes for great drama, especially if you're racing someone else to be there at the right time. A popular variant is for a character who's good at math to work out where the shadow would be pointing on the right day.
If the right day is specifically required, expect a cloudy sky to clear up at the last possible moment, so the characters won't have to wait a year to watch for it again. If the path for the light has obstacles, this trope may be combined with a Light and Mirrors Puzzle.
Related to Solar-Powered Magnifying Glass. Technically related to Total Eclipse of the Plot, in which the cast shadow of significance happens to be really big.
Examples:
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Arts
- Medici Chapels: The most important clue about the identities of the sculptures flanking Lorenzo de'Medici's tomb is the hour of the day when they receive sunlight. "Dawn" when the sun rises and "Dusk" when it sets.
Comic Books
- In Jon Sable, Freelance #15, Sable and an archaeologist are looking for treasure in a Central American pyramid. It's one of those designed so that a beam of sunlight shining through a hole in the wall will reveal the lock - but it only works on one day of the year that's months away. Sable points out that the ancient builders hadn't anticipated modern electricity and duplicates the effect with his flashlight.
Film — Animation
- In Epic (2013) the cast has to get the pod to the pool in the Leafmen base, where light from the moon at its highest point over a century will shine on it and it will bloom and pass on the life of the forest to Queen Tara's successor. If the pod blooms in darkness, it will bloom into Mandrake's heir.
- The Land Before Time: This is how Littlefoot's mother knew the way to the Great Valley.
- Used in Scooby-Doo: Camp Scare, to find a 1920s gangster's hidden loot.
- Titan A.E. uses this around 1/3 through the film.
Film — Live-Action
- Candleshoe: One of the clues to finding the hidden treasure at Candleshoe is "To the sunrise student, there's treasure among the books", so Casey decides to search for the answer in the mansion's library. After sifting through the books into the early morn, Casey finds the answer when the sun shines through the stained glass window, on which reads the next clue: "The paths of glory lead but to the grave."
- In Dr. Phibes Rises Again, the mechanical tomb in which Phibes sealed himself at the end of the previous film re-opens. Both the narration and Phibes's own mental monologue state that this event was triggered by moonlight falling on a specific location, indicating that a celestial conjunction Phibes has anticipated is imminent.
- Done with a very small statue set in the right place on a specific map in the 2013 film The Hunters 2013. It's unclear if this is really a valid way of locating a site or just the statue's owner making a Raiders of the Lost Ark reference to amuse her associates.
- One clue in National Treasure requires observing the shadow of a particular landmark at the right time of day. The filmmakers naturally forgot that the sun's exact position would also depend on the day of the year. Technically, the shadow would point to the right wall around that time of day regardless of the time of year. The fact that it was pointing at the exact brick is artistic license.
- In Raiders of the Lost Ark, the Staff of Ra must be placed in the Map Room at the right time of day in order for it to throw light upon the site of the Well of Souls. The villains have a staff of an incorrect length, so they are busy searching at the wrong place.
Literature
- In E.F. Bensen's short story "Gavon's Eve", an occult ritual can only be performed on the one night each year when moonlight shines straight through a very narrow crack in a specific standing stone. The position where the slender moonbeam lands marks where the ritual needs to take place.
- In The Hobbit, the keyhole of Lonely Mountain's hidden entrance is visible only at the right time on Durin's Day, a dwarven holiday. The instructions saying where and when to find the keyhole can only be read by moonlight on Midsummer's Eve - on years when the moon is in a certain phase on that date.
- In Jericho Moon, two groups of Canaanite treasure-hunters follow maps to the ruins of the destroyed city, seeking the place where two shadows cross in the moonlight. They wind up fighting each other to the death, not getting the chance to dig for the hidden wealth the maps promise. Both groups were following fake maps distributed by a surviving Jerichite merchant, who's been setting up such fatal collisions for years to pay back other Canaanites for not rescuing his city when the Hebrews attacked it.
- In Jules Verne's Journey to the Center of the Earth, the entrance to the passage leading Beneath the Earth is in a crater which is touched by the shadow of a mountain peak at noon during the last few days of June.
- Common in riddles in the Redwall series, such as in Mattimeo when the entrance to an underground city is located by following the shadow of a pine tree.
- In the Sherlock Holmes story "The Musgrave Ritual", the eponymous character finds the old crown jewels by the shadow of a tree. He manages to do this even though the tree is no longer standing. Even more impressively, he was able to do this when the directions were two hundred years old, meaning that the tree would have been considerably shorter when the directions were written down then it was at the time he followed them (although the story doesn't actually mention that point).
Live-Action TV
- 100 Things to Do Before High School: In "Become a Millionaire and Give It All Away Thing!", CJ, Fenwick, Crispo and Mr. Roberts take the crystal from Pooty's shield and place it on the Pooty the Bear bear statue. At 2:55, the sun hits the crystal, which shines a ray of light onto the ground. The four begin digging in the spot and find Alfred's million Pootabucks.
- Benson. "Fool's Gold". Benson discovers an old letter suggesting hidden treasure somewhere in the governor's mansion. They track it to an old room where the sunlight through the window (now bricked over) would show them the location.
- Krause: So all we have to do is knock a hole in the window and let the sun in!Benson: Why don't you knock a hole in your head and let some brains in? It's the middle of the night!
- They use a flashlight beam to simulate the sun.
- On Bones, Brennan confirms a suspected crime scene is where a victim's body was left hidden for years, by matching some faded spots on the victim's skull to narrow beams of light passing through a trio of holes in a wall.
- Buffy the Vampire Slayer. Spoofed when the Nerd Trio uses this technique to find a location on a map, only to have the map burst into flame from the concentrated sunlight.
- The Anasazi calendar (mentioned below) makes an appearance in an episode of Carl Sagan's Cosmos: A Personal Voyage.
- The two-parter Cliffhanger that bridged the first and second seasons of Criminal Minds involved the Serial Killer of the Week leaving elaborate clues for the team. One of these included a riddle that involved Middle English terms for times of day, and the shadow of a sword which is lodged in a corpse. Given that there is only one window in the apartment, they overthink this one and use a flashlight to find the exact spot.
- In the CSI: NY episode "Manhattanhenge," the search for the Compass Killer's lair and his next target is guided by the suspect's obsession with angles of sunlight over the city. Subverted in that Sheldon calculates in advance where the sunlight will fall, rather than waiting to observe it.
- In the Leonardo episode "Dragon Hunt", this is one of the clues in the treasure hunt. Leonardo figures it out. Mac and Lisa, following, don't realize the significance of the time of day, and follow the landmark making the shadow.
- In the first storyline of The Librarians 2014, Cassandra calculates a whole series of Sundial Waypoints at the Black Forest henge, all in her head and in less than a minute.
- They tested this on MythBusters and found that it works for a few minutes at most (see the Real Life examples).
- In the miniseries Treasure Island In Outer Space, the location of the treasure is indicated by the shadow of a particular spire of rock at a particular time of day.
- In the Made For TV Movie The Trial of The Incredible Hulk, Matt Murdock has a clerk use a map of the city, a ruler (representing a specific building), and a table lamp to figure out the location of David's flophouse. David had mentioned the Fisk Building blocking the sun.
Tabletop Games
- Used in the Call of Cthulhu supplement Terror from the Stars, for the adventure "The Temple of the Moon". In the temple there is a light shaft that allows moonlight to enter, and a pool with a map on the bottom. If the Tablet of the Moon is placed atop the light shaft at midnight under the light of the full moon, the moonlight will be refracted into a bright point of light on the map, showing the location of the main temple of Shub-Niggurath.
Toys
- BIONICLE: subverted in the Mata Nui Online Game; the Great Sundial is, of all things, underground, so Takua has to use a gnomon and a Lightstone to simulate 4 o'clock on it to open it.
Video Games
- Drawn:
- In Drawn: The Painted Tower, you must assemble pieces of glass to block most of the light shining through a window, leaving an arrow-shaped part unblocked so sunbeams will point out a spot to dig.
- And in Drawn: Dark Flight, you must reassemble a bird-shaped kite so that, when flown, it can cast a shadow into exactly the right spot to trigger the activation of the Library's door guardians.
- One of the clues in The Elder Scrolls IV: Oblivion is only seen when the sun shines from a certain angle (at a certain time of day) on a gravestone.
- Eternal Darkness uses this twice. First, as a wholesale reference to Raiders of the Lost Ark, Michael Edwards must use a Staff of Ra to guide sunlight over a scale model of a city. Second, when back in Alex's chapter, she must use a similar trick in the Roivas mansion's observatory to open a special lock.
- Subverted in Kingdom of Loathing, in which you are sent on a (very long) quest to build a staff with a gem which will focus light onto a map of the kingdom showing where "The Holy MacGuffin" is buried. When you do it, it instead acts as a Solar-Powered Magnifying Glass, setting fire to the map, and revealing a trap door underneath.
- In The Legend of Zelda: Breath of the Wild, song lyrics recounted by various Rito provide clues about how specific shadows (or, in one case, a gap in a shadow) can lead Link to shrines or treasure.
- In order to find the correct brick to push in one puzzle of Monkey Island 2 Lechucks Revenge, Guybrush must use a telescope on a statue's hand, which will channel the sunlight through a window and then bounce on a mirror to illuminate the brick on the wall.
- In the Mystery Case Files game Ravenhearst Unlocked, repairing a stained-glass window causes a beam of sunlight to fall through it onto a flagstone in the floor, which conceals a needed item.
- In Nazi Zombies, a ray of light points to the location of the Mystery Box, although it's not actually from the sun since it's visible in night-time maps.
- In Quest for Glory II, a prophecy is quite clear that at a specific time, the moon will be caught between two constellations, and the door will open. The problem is that the moon won't pass between those constellations until the next night. The solution is to use your mirror to reflect the moonlight onto the door, which has the images of the two constellations on it.
- Scratches:
- The tip of the tower's shadow indicates the location of Mrs. Blackwood's grave, although it doesn't show up clearly enough for you to use this clue until the weather clears up.
- Also, to reveal a clue, you must clear a pathway for a beam of sunlight to fall upon a written message, which can't be made out otherwise.
- In Sonic Adventure's "Lost World" stage, set in old ruins, Sonic comes across a pitch-dark room except for the entrance, which is bathed in sunlight. He needs to find mirrors and point them towards one another at the right angles; the path the sunlight takes as it reflects from mirror to mirror is the path Sonic needs to follow to get to the other side of the room.
- One of the puzzles in Soul Reaver relies on this. In a twist, it requires you to do a typical mirror puzzle to get the beam where you need, then obscure it - which allows you to walk the shadow across a chasm.
- In Tomb of Zojir, you must place a gem-topped staff in position so a beam of moonlight lands on the right spot. While this doesn't directly reveal a location, it does reveal the code necessary to open another chamber's door.
- Most of the puzzles inside El Caracol in Tombs & Treasure are of this variety, involving metallic globes and a set of panpipes to trigger them.
- In the online multi-player expansion of Uru, the wedges for the Pod Ages can only be acquired by jumping through a portal that appears for a few seconds at a time on a set daily schedule. In one of the Ages, beams of light from cracks in the Pod roof will fall directly on four marked spots on the floor when the time is right for the portal's appearance.
- In an artificial-light variant, to find one exit in Uru: Ages Beyond Myst requires turning off lights until a specific shape of shadow forms on the floor, that indicates the route to the doorway.
Web Original
- SMPEarth: The first clue to the Octangula ARG is at the Southwest Octangula, where a giant sundial-like structure is located, which the players use to find clues.
Western Animation
- Alfred J. Kwak: In the Egypt episodes, the secret entry point to the Pharaoh's throne room in the pyramid is only visible at high noon when a mirror reflects the light.
- Happens twice in Avatar: The Last Airbender:
- Aang's first real communication with Roku could only happen on the winter solstice, which was indicated by a beam of sunlight shining on the forehead of Roku's statue.
- A straighter use of this trope is the door to the Sun Warrior temple. It would only open on a solstice, when the sun, focused through a lens, struck a stone on top of the door frame. Aang and Zuko were able to cheat by reflecting the focused light beam onto the stone, rather than waiting for the right day of the year.
Aang: Monkey-feathers! The solstice again?
- Parodied in Family Guy. When Peter has to dig his old black book out of the attic, he has to set up a staff and crystal to focus the light and open a secret door.
- Nature Cat:
- Inverted when the shadow of Hal's doghouse is used by the four friends to determine the time when a visiting squirrel will return. They already know where the shadow needs to appear from Daisy's photo, just not when it will get to the designated spot.
- Played straight with the Golden Sunstone, a pictograph-carved rock face on which the sun casts three vertical beams through crevices at noon on the Autumnal Equinox.
Real Life
- The clues in the book Masquerade led to Real Life buried treasure (a gold hare), which could be found at the tip of a shadow of a particular cross at midday of the equinox.
- Once rebuilt, the buildings of New York's World Trade Center will be arranged so that, every morning on September the 11th, a commemorative beam of sunlight will fall precisely on the spot where the first 9/11 airliner struck the Twin Towers.
- Some ancient pre-Columbian archeological sites have this effect on certain dates: "the Chichen-Itza's equinox shadow serpent
" and the "Anasazi Calendar on the equinoxes and solstices" are some examples.
- The Clock of the Long Now, a mechanical clock designed to last 10,000 years without any human intervention, uses this to keep itself synchronized with the actual time. Every day at noon, the sun's light is focused through a prism* , which heats a piece of metal. As the metal expands, it triggers a mechanism which causes the clock to run faster if it's behind, and slower if it's ahead. This only works to count days, rather than actual elapsed time, because the rotation rate of the Earth is not constant. It happens that the biggest source of error in the Clock's timekeeping (about 10 parts per million) is climate change potentially melting the ice caps, which could make the length of the day up to 1 second longer.
- At the Canadian War Museum in Ottawa, a sunbeam shines on the headstone of the Canada's unknown soldier of WWI, at 11:00 on November 11, the hour and the day that World War One ended.
- On a similar note, at 11:11 am on November 11th, in Anthem, Arizona, USA, sunlight shines directly through gaps in five pillars (one for each branch of the U.S. military) at the Anthem Veterans Memorial. Most days, the sun's rays through the disks create a random arrangement of light on the Memorial's flagstones, but at that single moment each year, the circles line up to highlight the Great Seal of the United States.
- Egypt's Great Temple at Abu Simbel was constructed in such a fashion that twice each year, a beam of sunlight would shine deep into a narrow passage and fall upon an alcove in which idols to the site's patron deities were displayed. Subverted since 1968, when the entire temple was painstakingly relocated to a higher elevation to prevent it from being flooded by the Nile after the completion of a dam. Sunlight still penetrates the passageway twice a year, but on the wrong days.
