Hacker News Reader

The way we detect planets only detect some of them.

The best method is to notice when a planet passes in front of its star, by how it gets slightly dimmer. That only works if its orbit happens to be directly between us and that star.

View on HN

We can also detect them by a Doppler shift of the star, because the planet (if big enough) will move the star as it orbits. This works when the transit method fails, but provides fewer data on the planet itself.

It also only works for big enough planets close enough to the star.

Doesn't work when the orbit is perpendicular to our sight line either.

this would not show any planets beyond saturn for solar system, for example

Reply on news.ycombinator.com