We assume that the way humans see the world has some correspondence to objective truth. That’s not necessarily correct. Let's do a thought experiment where we have a quick chat with an alien species to see how mistaken we are about the universe.
So we’ve made contact with aliens, and some people are celebrating and others are melting down with fear, but the overall consensus is that we should ask them over for tea or something. It’s likely that tea time conversation will be a bit stilted. What do people talk about other than what they have in common? Although we may assume that we have the whole universe in common, the aliens, if we just tweak their senses a bit, may be living in a different universe from ours.
Let’s start with the sense we use most to interact with the world. We knew there were aliens out there because we could see the sun, the moon, the stars, and even the planets in the solar system. And we could see those things with our naked eyes, because we can pick up certain wavelengths of light. All we had to do, even hundreds of years ago, was turn out eyes upwards (sometimes with the aid of telescopes, true) to see the potential for other worlds. The same is not necessarily true for the aliens.
The tweaks to their vision might be minor. They might just pick up, visually, on different stars than we do, seeing things in the infrared range or the ultraviolet range. Since we now have plenty of telescopes scanning the skies and picking up on parts of the electromagnetic spectrum that we can’t see, it would just be a matter of superimposing our visual star maps on their visual star maps to get some common ground.
But what if they don’t see anything remotely within our visual spectrum? Let’s say that they evolved on a planet not powered by light from a nearby star, but from vents from the planet’s core. Light, and vision, might not be a big component of their senses. Perhaps, for whatever reason, they only see ultra-high energy light given off by quasars, which perch at the centers of galaxies. They wouldn't realize there was the possibility of life in the outer reaches of a galaxy before we contacted them. Or they might only be able to see quickly changing light, and can only navigate space by pulsars. There’s even a possibility that they can only, visually, pick up on very faint microwaves, and it never occurred to them that there was life in the universe, because they only saw the faint, homogeneous smear of the cosmic microwave background. Never mind how we’d contact a society like that, how would we even begin to explain who we are and where we came from?
If we sorted through the first contact and they got to Earth, there could be even more problems with light. If they only saw in x-rays, we very well might look like bags of bones with weird, invisible flesh around them. (Also, any prolonged exposure to alien “flashlights” would kill us.) But what, for example, if they only saw polarized light? We know that some animals can see polarized light, and it’s thought that they navigate by the natural polarization that light goes through in the sky throughout the day. But what if a species can see polarized light and nothing else? Because vertical and horizontal surfaces polarize the light that hits them, the aliens would see a multicolored sky, blinding walls of light from windows, the hoods of cars, lakes, and puddles, but wouldn't be able to see any humans. (Although they would, in sunlight, be able to catch the intermittent glare coming from our glasses. How creepy would that be for them?)