From the point of view of some researchers, visitors from other worlds have been watching us closely for a long time. Sightings, close encounters, ships in secret bases, among others. But from a more scientific point of view, the way of being detected is different.
Nearby systems
There are some 2,034 star systems close to our planet, in astronomical distance “about 300 light years” and these have worlds similar to ours.
The observations we make from here to search for exoplanets (planets similar to ours outside our solar system) are based on several techniques.
The brightness of the stars causes the planets orbiting them to be obscured, as if you were trying to see behind a powerful spotlight. That’s why there are more specific methods for finding these orbs.
The two main ones are radial velocity and transit.
- Radial velocity: the gravity of the planet orbiting a star, and the gravity of the star attracting it, interact causing a wobbling effect on the star, thus, if the planet orbits every 24 hours, every time it passes in front of it, this effect will be visualized.
- Transit: it is a simpler technique based on the observation of shadows on the star, when a planet passes in front of it while focusing, a small shadow will be seen, and if this event is repeated every few hours or days, a possible world will have been detected.
An intelligent civilization that had the technology to search for other planets, and their star system was pointing towards us with a direct view of our location, would have about 5,000 years ahead of them to continue studying our position.
It is estimated that there may be 1715 star systems that have an orientation suitable for imaging the Earth for about 5,000 years, i.e., a margin of 10,000 years in total of study.
The nearest stars that have the possibility of seeing us, “in case there is an intelligent civilization” are 100 light years away from us. So a radio signal emitted in the 1920s is now reaching these systems or stars, and thus, their planets.
Are your measurement and observation instruments similar to ours?
We simply have no idea, we do not know if their technology will be superior or not, nor at what stage of evolution they are in, and not even if there is anyone watching. What is very likely is that new candidate worlds will appear that can perceive us.