Support & reference desk
Two satellite frames of one point on Earth, years apart, with a curtain you drag between them. This page explains what the imagery can show, what it cannot, and how to reach a person about it.
Write to fuwubakerad847@gmail.com — answered within 1–2 working days.
Night lights are the short one: that archive opens on 30 Nov 2016.
Products you can switch between on the compare screen
Every frame in the app comes from NASA's EOSDIS GIBS service. It is public imagery, free to browse, and the app asks for it with no account and no key. Each product has its own archive and its own grain, and switching product switches which days have an answer for you.
The credit line under the frames — Imagery courtesy of NASA EOSDIS GIBS / Worldview — is part of using the service and is repeated in Profile. NASA does not endorse the app, and the app does not process, correct or re-colour what the service returns.
Map → compare → keep
Read this before deciding something is broken
ZeusEye shows survey imagery, not aerial photography. At the finest zoom the service publishes, one pixel covers roughly 250 metres of ground: a coastline, a reservoir, a burn scar, the edge of a city. A street, a building, a car or a person is far below that, and no amount of zooming brings one back — past the cap the app would only be magnifying the same picture, so it stops and says so.
Clouds are part of the record, not a fault in it. A frame can be three quarters white because that is what was above the place that morning; the app estimates the cover and suggests moving a day. There are also days when the satellite simply did not pass over that tile, and stretches the archive lost to reprocessing — both are real gaps, and the app offers the nearest day that does exist rather than inventing one.
One product bends this further: vegetation is a sixteen-day composite. Every day inside the span answers, but the picture you get is the composite covering that day, and the caption under the frame names the day the composite actually belongs to. Two dates a week apart in that layer can legitimately return the same picture.
What the app says, and what it means
The satellite didn't pass over this tile that day.
Not an error. Take the nearest available day from the button the app offers, or step the date by one.
That is as far back as this layer goes.
You have hit the start of that product's archive. Natural colour and snow reach back to February 2000; night lights only to November 2016. Switch the product and the same date may well answer.
No connection to the tile service.
The frames come over the network, one tile at a time. Whatever was downloaded before stays on the device and still opens; the rest fills in when the connection is back. A VPN can also route the request somewhere with no answer for it — worth turning off before writing to us.
This frame could not be assembled.
Tiles for that date and area went missing on the way. Pull the date one day either side; if the same place and date fails repeatedly, that is exactly the case to send us.
My Places and Profile
A saved place carries its coordinate, its product and its pair of dates, and the list can be sorted by name or by when it was added. Renaming and deleting are both on the place itself; deleting removes the date pair and its thumbnail and nothing else.
Profile holds a name and an avatar picture of your choosing, the count of places and comparisons you have made, the choice between plain degrees and degrees-minutes-seconds, the interface language, this support address and the privacy policy. The observer name and picture are decoration — they are stored on the device, and the app has no account to sign into and nothing to sign out of.
Below all that sits Reset data. It clears saved places, the counters and the tile cache in one move, and it cannot be undone. Use it if the app is behaving oddly, or before handing the phone on.
Permissions, storage, money
| Location | Asked only if you use “find me on the map”, and only while the app is open. It centres the map on where you are. Decline it and everything else works; the map simply starts where you last left it. |
|---|---|
| Photo library | Two separate requests. Reading, to put a picture of your own on the observer avatar. Writing, to drop the before-and-after composite — both dates burned in — into your gallery. |
| Notifications | A standard system prompt, wording fixed by iOS. Decline it and nothing in the app closes off. |
| Tracking prompt | The iOS dialogue asking to allow tracking. It is about attribution — which campaign brought the install and whether it worked. Declining changes nothing about the maps or the archive. |
| On the device | Saved places, counters, your observer name and picture, downloaded tiles. None of it is uploaded, and Reset data removes all of it. |
| Money | None. No purchases, no subscription, no paid tier, nothing held back behind a payment. The imagery is free to begin with. |
Which identifiers and analytics leave the device, who processes them and how long they are held is set out in the privacy policy. If you want a copy of what is held about your install, or want it erased, write to the address above from the address you would like the answer sent to, and say which it is — there is no account to look you up by, so the more you can tell us about the device and the approximate install date, the better we can find it.
Mail reaches a person, not a queue robot, and gets an answer within one to two working days. Four lines save a round trip: