What Is an Aircraft Transit?
An aircraft transit is when a plane appears to pass in front of something else in the sky, usually the Moon or the Sun. From your location, the aircraft lines up with that object for a very short moment. Sometimes it lasts less than a second.
It sounds simple, but it is actually pretty hard to catch. The aircraft needs to be in the right place, at the right altitude, moving in the right direction, while the Sun or Moon is also in the right position from where you are standing.
That is why a lot of people miss these shots. You can have the Moon framed perfectly, your camera ready, and then nothing happens. Or a plane crosses nearby but just misses the Moon. Sometimes it looks close to your eyes, but through a long lens it is nowhere near.
Why are aircraft transits so quick?
Aircraft move fast, and the Sun and Moon are small targets in the sky. The Moon is only about half a degree wide. That means the path has to be very accurate from your exact location. A plane that crosses the Moon for someone a few kilometres away may completely miss it for you.
This is also why aircraft transit photography can be frustrating. You are not just waiting for a plane. You are waiting for a very specific alignment between your position, the aircraft, and the object in the sky.
Moon transits
Moon transits are popular because they are safer and easier to practise than Sun transits. You do not need solar filters for the Moon, and you can usually see your framing clearly through the camera.
A Moon transit can happen during the day or night, but the best results often come when the Moon is bright, sharp, and sitting in a useful part of the sky. Aircraft near airports can be good subjects, but higher aircraft can also work depending on your location and lens.
Sun transits
Sun transits can look incredible, but they come with serious safety rules. You must never look at the Sun through a camera, telescope, binoculars, or lens unless you are using a proper solar filter. This is not optional. It can damage your eyes and your gear.
When done safely, Sun transits can show the aircraft as a sharp black silhouette crossing the solar disc. Depending on your gear, you may also capture contrails, heat shimmer, or other details.
Why I built Transit Chaser
I built Transit Chaser because guessing gets old very quickly. I wanted something I could leave running while I had my camera ready. The app watches live flight data and compares nearby aircraft with the position of the Sun or Moon from your location.
It does not guarantee a perfect transit. Aircraft data changes, flights turn, altitude changes, and live data can be delayed. But it gives you a much better chance than just standing outside and hoping.
In simple terms
An aircraft transit is a short alignment between you, a plane, and the Sun or Moon. Transit Chaser helps you know when that alignment may be about to happen, so you can be ready instead of guessing.