Dark Sky Walk

Aryan Deshmukh — Fri, 09 Oct 2026 17:03:36 +0000

This is a submission for the Hacktoberfest Open-Source AI Challenge Week 1: Touch Grass

What I Built

Dark Sky Walk: an offline night-sky companion that gets people out of the house after sunset.

Most stargazing apps keep you staring at the phone, and they break down where it matters most: dark spots with no signal. Dark Sky Walk flips that. Before you leave, you ask in plain language, "What can I see tonight, and where should I go?" The app works out what is visible (planets, the Moon phase, bright stars, any meteor shower peaking this week), checks cloud and moonrise timing, and suggests a short walk to a darker nearby spot with a simple "look here, then here" checklist you can follow with your phone in your pocket.

Once you are outside, the screen is the shortest part of the experience: a red-light, low-brightness card for each target, plus optional spoken prompts so you can keep your eyes on the sky.

Who it is for: beginners who have never found a constellation, families looking for an evening activity, and hikers or campers who want to make use of clear nights without any signal.

How I Built It

Local language model: a small open-weight model (for example a quantized Llama, Qwen or Gemma variant) running through a local inference runtime such as llama.cpp or Ollama. It turns questions like "what's good tonight?" into a friendly, ordered observing plan.
Open astronomy data: an open-source ephemeris library (such as Skyfield or Astropy) with a downloaded star catalog calculates real positions of planets, the Moon and stars for your exact time and location. The model never guesses sky positions; it only explains them.
Tool-calling agent loop: an open-source agent framework lets the model call the ephemeris, moon-phase and sunset tools, then assemble the answer.
Offline maps: open map data (OpenStreetMap extracts) to find parks, hills and open fields nearby, plus a light-pollution layer to rank them by darkness.
Interface: a lightweight web or mobile UI in night mode, with large text, red-tinted colors and optional text-to-speech from an open voice model.
Field-first design: all data and models are downloaded once at home, so the whole pipeline works on a laptop or phone with no connection.

Why Does Open Innovation Matter?

It works where the signal doesn't. Dark skies are found far from cell towers. A cloud API fails exactly where the app is needed; a local model keeps working in a field or on a hill.
Your location stays yours. The app only needs to know where you are standing at night. Running locally means that information never leaves the device.
It costs nothing to run. No API bills or rate limits for a hobby project that people might use every clear night.
You can adapt it. Swap in a smaller model for an older phone, fine-tune it to explain things at a kid's level, or change the agent's behavior (for example, favoring meteor showers in August) without waiting for a provider to add a feature.
The science stays trustworthy. Open ephemeris data does the astronomy, and the model handles only the explanation, so the app stays accurate and inspectable instead of hallucinating where Jupiter is.

DEV Community: Aryan Deshmukh

Dark Sky Walk

What I Built

How I Built It

Why Does Open Innovation Matter?