How do we know that our solar system is not the only exisinting planets?

Question

Because the closest stars are millions of years away how do we know they are not already gone leaving just earth and our solar system alive today?

Answer 1

Around 150 planets around other stars have been detected. This is done either by looking for a "wobble" in the velocity of a star caused by an orbiting planet, or seeing the periodic dimming of the star as the planet crosses in front of it (or both). Almost all of these planets are within 1000 lightyears, so we seee them as they were 1000 years ago. Since planetary systems (like our own) last billions of years, they are almost certainly all still there.

Answer 2

There's no way to tell what's happened to any star since the light we see now left it on its way to earth, but since there's at least one star with planets within 30 light-years of Earth, we know that that star's planets were still there as recently as 1977 (when Star Wars: A New Hope came out...just for perspective). Of course, we don't know if any of those planets have life on them--Earth could quite possibly have the only living beings in the galaxy.

Answer 3

Lots of other solar systems with people exist.
Many stars have gone out of existence thousands or millions of
years ago.
Like 1987A we may be lucky to see the odd one.

Answer 4

We don't!
Antares and Arcturus are so big that they make our huge sun infinitely tiny by comparison and it-our sun-has a very long life expectancy.
Those who study the cosmos say there are billions more galaxies beyond ours.
By the way - do you, like me, wonder why beauty salons are run by people called cosmotologists? Or why Cosmo Kramer was so 'out there'? Now we know.

Answer 5

we do not know other worlds yet