Stellarium Web Visible Planets Overlay

WHAT IT DOES

Stellarium Web Visible Planets Overlay automatically scans Stellarium Web sky map pages and extracts planetary position data including planet names, visibility status, current magnitude, right ascension and declination coordinates, and rise/set times when available. The tool displays a floating overlay panel that summarizes all visible planets for your current location and time, with color-coded visibility indicators—green for planets above the horizon and red for those below. Planets are sorted by visibility priority, making it easy to see which planets you can observe right now. Each planet entry shows its magnitude (brightness) and any available coordinate or rise/set information. A legend explains the visibility color-coding. You can toggle planet labels on the sky map on and off with a single click, and your preference is saved across sessions. This provides a quick, at-a-glance reference for what's visible in your night sky.

WHERE IT RUNS

This extension operates exclusively on stellarium.org domain pages that contain sky map content—specifically pages with "/map" or "/web" in the URL path, or pages that display interactive sky maps and astronomical data. It works alongside the free BotGentz companion extension, which provides the necessary DOM access and page interaction capabilities. The visible planets overlay runs entirely within your local browser instance and does not communicate with any external servers or APIs. All planetary data extraction, visibility analysis, and preference storage occurs on your machine, ensuring your stargazing activity and location preferences remain private. It supports all modern Chromium-based browsers (Chrome, Edge, Brave, Opera) and Firefox when paired with the BotGentz bridge.

HOW TO USE

After installing both BotGentz and this visible planets overlay, navigate to any Stellarium Web sky map page. Within 1-2 seconds, a panel appears in the bottom-right corner displaying a list of planets. The "Planets" section shows each planet with its symbol and name, with visible planets shown in white and bold while planets below the horizon are shown in gray. A status indicator displays "● Visible" in green or "○ Below horizon" in red next to each planet. Details for each planet include magnitude, rise time, set time, and coordinates when available. The "Legend" section explains the color-coding. The "Settings" section includes a toggle to show or hide planet labels on the sky map—your preference is saved automatically. The panel provides a complete overview of what's currently observable in your night sky.

PLANETARY DATA EXTRACTION AND VISIBILITY ANALYSIS

The visible planets overlay uses a multi-strategy extraction system to locate and parse planetary data from Stellarium Web pages. It first attempts to find structured planet label elements using selectors based on the site's typical class naming patterns, including "planet-label," "label-planet," and "planet-name." Each detected planet label is analyzed to determine the planet name through keyword matching against a comprehensive list of planet names and astronomical symbols. Magnitude is extracted through pattern matching for "mag." or "magnitude:" labels, coordinates through pattern matching for RA/Dec pairs, and rise/set times through pattern matching for "rises at" or "sets at" patterns. Visibility status is determined through text analysis—if the label text contains "below horizon," "not visible," or "set," the planet is marked as below horizon; otherwise, it is considered visible. For pages where structured planet labels are not found, the tool falls back to scanning the page text for planet names and extracting surrounding context to determine visibility and available data.

THE PANEL

The visible planets overlay panel is a compact, functional overlay that integrates into the Stellarium Web page. It can be dragged by clicking and holding the title bar, positioning the panel anywhere on the screen for optimal visibility while you explore the night sky. The panel includes a built-in snap feature that automatically aligns to the nearest screen edge when released within 48 pixels, keeping your workspace organized. Click the collapse arrow in the top-right corner to minimize the panel to a small icon bubble showing a gear emoji, preserving screen space while keeping the tool accessible. The panel is not resizable in this version, maintaining a consistent compact size that works on all screen resolutions. Press the Escape key to instantly hide the panel; press Escape again to restore it. All position, collapse state, and planet label visibility preferences are saved locally using GM_setValue and persist across browsing sessions.

PLEASE NOTE

This extension requires the free BotGentz extension to function—the visible planets overlay does not work standalone. Stellarium Web occasionally updates its page layouts and map presentation formats, which may temporarily affect data extraction accuracy. The tool extracts planetary data from the visible page content; if sky map data is loaded dynamically after page load, you may need to wait a moment or refresh the page for the panel to populate. Visibility status is determined from text labels and may not reflect real-time positions. The tool does not store or transmit any data; all planetary data extraction, visibility analysis, and settings are processed and saved entirely within your browser. This tool is designed for personal stargazing assistance and is not affiliated with or endorsed by Stellarium or its parent company. Planetary positions and visibility are subject to change based on your location and time; always verify observations using the official Stellarium Web interface.