Hi hunters, I’m Elliott, an astronomy student and indie developer based in Sydney, Australia. Over the past few months, I’ve been working on a project that brings a surprisingly overlooked concept to life — how fast the Earth is spinning beneath your feet, right where you stand. We often learn that the Earth rotates at ~1670 km/h at the equator… but what about in London? In Sydney? In your backyard? That’s where SiderealLab comes in. What is SiderealLab? SiderealLab is a scientific calculator that lets you estimate your local rotational speed based on: - Your latitude (manual input or preset cities) - Your observation time (standard 24-hour vs. sidereal tracking) - Real-time charts and downloadable PDF/CSV/Markdown reports The Basic (free) version gives you full access to basic calculations and exports. The Pro version transforms SiderealLab into a fully-featured toolkit for educators, researchers, and science enthusiasts. Why I built it As an astronomy student and long-time stargazer, I often found myself explaining the concept of rotational velocity — and realized how hard it was to visualize or calculate this intuitively. I wanted something accurate, educational, and accessible — so I built it. At this moment, I chose Streamlit for the interface, Supabase for secure login & role management, and Python for the scientific backend. It's all wrapped into a tool that I hope educators, students, and space lovers will find useful (and a little magical). A note on sidereal time (why accuracy matters) One core feature of SiderealLab — and the reason I built it — is to allow the use of measured sidereal time. Instead of assuming a fixed 24-hour rotation, users can input two timestamps (T₁ and T₂) from two consecutive nights of observing the same star, when it passes the same right ascension and declination. This method captures the real sidereal day at that specific location, offering more accurate rotational speed data. This isn’t just theory — it’s the foundation of how real observatories calibrate time and motion. And I wanted learners to experience that firsthand. What’s in the Pro version? (Pro is building and coming soon) In addition to all core features, SiderealLab Pro includes: - ΔT (sidereal day) and angular velocity calculations - Export options: `.csv`, `.pdf`, and `.md` reports - Auto-generated PDF reports (via markdown2 + WeasyPrint) - File naming with timestamped targets for scientific use - Unit toggle between km/h and m/s - RA/Dec drift correction module (simulated or API-ready) - Visualization charts: - Latitude vs. Local Radius - Latitude vs. Rotation Speed (km/h) - Latitude vs. Rotation Speed (m/s) - Multi-platform development: Python GUI, Swift, MATLAB in progress - Notion integration planned; GitHub channels coming soon This edition is built for those who want publishing-ready output and deeper analysis tools. An iOS app based on SwiftUI is also desigining and building and testing later. I’d love to hear your thoughts: - Would this be useful in your classroom, lab, or stargazing community? - Are there features you’d want added? (Mobile? Real-time GPS? Custom time-based simulations?) - Do you think this concept could evolve into a larger toolkit for astronomy education? Thank you so much for reading, and for supporting indie projects like this one. And remember — even if you’re standing still… you’re always spinning. — Elliott P.S. At 33.80° south, I’m currently spinning at 385m/s at a 5,294.20km local radius. How fast are you going?

Elliott Cao

SiderealLab

Maker

📌

26d ago

Supa Liu

Wow, experiencing the change in Earth's rotation speed based on location and time during stargazing sounds incredible! The visualizations must have been super effective in making that concept understandable.

25d ago

@supa_l Dear Supa hunter, thanks for your comment and valuable suggestions with a so exciting and high expectation. As mentioned in the description, I designed it before I purchased my first Equatorial Mount, and until I had one, while my stargazing activities with other amateurs outside, I created more details not only just calculate a cold number for local speed. I will release the Pro version soon, and also I should create more interesting tiny functions, even just an improved UI. lol~ Thanks for your comment and valuable suggestions again. Elliott Carinae (My name is Elliott Cao, I am from the Southern Night Sky, I belong to the constellation of Carina, Ahhha~)

@elliott_cao When someone truly loves something, they always find ways to create beauty in it. Elliott, your project may deal with cold numbers, but to me, it feels like you're doing something incredibly romantic.

Aryan Sharma

Product Hunt Dark Screen

Just a Feedback- You don't need Authentication before even people checking what and how your product is!

24d ago

@aryansharma17 Hi Aryan, thanks for your feedback. I am a newbie here, actually not sure how to derive a no-authentication free access page, and an auth site extra? Keep learning, receiving and thinking of all feedback. Thanks again.

@elliott_cao Welcome Elliot, you will figure out things.

In your code, there is middleware file or something related to it. There you have to remove it from Home "/" page and use it when people using actual thing.
Or maybe you can provide a landing page and show what your product does.

SiderealLab

Find out how fast you are spinning — from your latitude

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