Common questions
My bodies flew off the screen
That's usually correct physics, not a bug - a fast body can leave the visible area quickly. Pinch to zoom out to bring it back into view, or tap the Center button to reset the camera to the origin. Tapping any empty spot on the canvas also re-centres the view on that point.
How do I control speed and gravity?
On iPhone and iPad, drag from inside the faint half-circle at the left edge of the canvas, up or down, to change the simulation speed; do the same on the right edge to change the gravitational constant, G. In both cases dragging up lowers the value and dragging down raises it. You can start the drag inside the half-circle and keep moving your finger even after it leaves that area.
How do I zoom?
Pinch with two fingers, anywhere on the canvas. The point between your fingers stays fixed, so you can zoom and pan with the same gesture.
How do I see a body's exact numbers?
Tap it. A small panel appears showing its mass, position, speed, momentum and kinetic energy, updated live while the simulation runs. Tap it again, tap another body, or tap empty space to dismiss it.
How do I change the language?
StarSim starts in your device's language automatically, when it is one of the six supported languages. You can switch it anytime with the dropdown next to the title, from the menu opened by the ☰ button.
Which languages are supported?
English, German, French, Dutch, Italian and Turkish - including the built-in rules, astrophysics reference and history sections.
Can I save a system I've built?
Not at the moment. StarSim keeps no history and no saved presets between launches; every session starts from the built-in systems (a binary star, our Solar System, a collision test) or a blank table you fill in yourself. If you want to keep a set of numbers, the simplest way for now is to note them down outside the app.
What does the app need to run?
An iPhone or iPad with iOS 15 or later. No internet connection is needed - the simulation runs fully offline and never has to reach the network.
Are there ads or extra purchases?
No. You buy the app once. There is no advertising, no subscription and nothing locked behind an in-app purchase.
Is it suitable for children?
Yes. There is no chat, no user-generated content, no advertising and no link to strangers. It's a physics tool rather than a game aimed at a particular age - the simulation behaves the same whether you're nine or ninety.
I would like a refund
Purchases and refunds are handled by Apple, not by us. Use reportaproblem.apple.com with the Apple Account you used to buy the app.
Reporting a problem
The more of this you can include, the faster it gets fixed:
- what you were doing when it happened - which system was loaded, and roughly how many bodies were on screen
- device model and iOS version
- the app version, and the language you were using
- a screenshot, if the problem is something you can see
Privacy
The app collects no personal data at all, and saves nothing on your device between launches. The full text is in the privacy policy.
Who is behind this
StarSim is made and supported by GER IT Consultancy, a sole proprietorship registered in the Netherlands, and is part of the Neuron Burst family of apps.