One Light Day
Voyager 1 · One Light-Day
Only for iPhone
Free · In‑App Purchases · Designed for iPhone. Not verified for macOS.
iPhone
On 18 November 2026, join Voyager 1 at a symbolic horizon: one light-day from Earth. Explore its journey, Golden Record and our place in space.
One Light Day is a free digital monument celebrating Voyager 1, humanity’s farthest spacecraft.
On 18 November 2026, Voyager 1 is expected to reach a remarkable symbolic milestone: a distance from Earth that light takes approximately twenty-four hours to cross.
One Light Day transforms that immense distance into a personal and interactive experience.
DISCOVER THE JOURNEY
Follow Voyager 1 from its 1977 launch, past Jupiter and Saturn, through the heliopause and into interstellar space.
EXPERIENCE THE DISTANCE
See its estimated distance from Earth, one-way light time and the countdown to the one-light-day horizon.
MEET VOYAGER 1
Examine and interact with a detailed 3D model of the spacecraft that has travelled farther than any other human-made object.
EXPLORE THE GOLDEN RECORD
Discover the sounds, images, greetings and scientific symbols selected to represent Earth to the cosmos.
FIND VOYAGER IN THE SKY
Use your iPhone’s location and motion sensors to face the estimated direction of Voyager 1.
SEND A SYMBOLIC LIGHT
Begin with prime numbers, then encode a short human word as flashes of light. After sending it, follow a twenty-four-hour chronograph representing the photon’s journey.
A FREE EXPERIENCE
One Light Day contains no advertising and requires no subscription. Every experience is available to everyone. Optional contributions help maintain the app and its website but never unlock additional functionality.
Voyager 1 will remain humanity’s farthest pioneer, our avant-garde in interstellar space.
One Light Day is an independent educational, cultural and artistic tribute. It is not affiliated with or endorsed by NASA or JPL. Scientific distances, directions and times are estimates and are not real-time telemetry.
Ratings & Reviews
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The developer, Jean Marc Moro, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Jean Marc Moro
- Size
- 16.1 MB
- Category
- Education
- Compatibility
Requires iOS 18.0 or later.
- iPhone
Requires iOS 18.0 or later. - Mac
Requires macOS 15.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 2.0 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- In-App Purchases
Yes
- One Light Day $4.99
- Farther Signal $2.99
- Bright Signal $1.99
- Small Signal $0.99
- Copyright
- © 2026 Jean-Marc Moro