If you were 30 light-years from earth looking at earth it would look like 1990s. Light year is how far light travels in a year. Since everything we see is lightwaves being interpreted by our brain, light hits earth in 1992, reflects an image off, travels for 30 years and you see it today, if you were there to receive the image.

Or a mirror 15 light years away we could see the earth 30 years ago