Three distant giant planets circle their stars so closely that a year on them lasts just a few Earth days. These worlds are called hot Jupiters, and their orbits are a real puzzle: how did they end up right next to the star if they were born far away, in the cold outskirts of the system? One key clue is the angle at which a planet orbits relative to the star's rotation. If the orbit is tilted, something must have given the planet a strong shove or flipped it over in the past.
Astronomers measured this angle for three hot Jupiters: HAT-P-49 b, HAT-P-57A b, and XO-3A b. They used a method similar to observing a shadow: when a planet passes in front of its star, it briefly blocks part of the star's light, and the shape of this "shadow" reveals how the planet moves. The first planet's orbit turned out to be almost perpendicular: it flies "on its side," like a top spun the wrong way. The second planet moves exactly in the plane of its star's equator, as if nothing ever disturbed it. The third takes an intermediate position, an angle of 38 degrees, and so far, few planets with such a "half-tilt" are known.
The different tilt angles suggest that planets may have different migration paths: some are gently pushed by the gas disk, while others experience violent collisions or gravitational "kicks" from neighboring bodies. It's like three people arriving at the same room by different routes: one straight through the door, another through the window, and the third doing a somersault. By studying such orbits, astronomers are piecing together a map of possible histories of planetary systems, including our own.
Orbital tilt is measured in degrees: 0 means the planet orbits in the star's equatorial plane, 90 means the orbit is perpendicular, and 180 means the planet moves in the opposite direction, as if it were flipped over.
In the movie "Interstellar," the planet Miller orbits a black hole so closely that time flows differently on it: that's a fantastic extreme, but hot Jupiters also live in extreme proximity to their stars, where tides and radiation distort their fate.