The Basics of Astronomy
The Edge of the Universe
In Astronomy we learn from what we can observe, just as in any other science, and just like any other science we are limited in our Observations. We cannot travel to other stars with our current technology, we have a hard time finding planets, especially Earth like planets, outside our Solar System, and we are limited by Light itself.
Since we cannot travel very far, and even our most advanced Satellites and Spacecraft have never left the Solar System, we are limited in our sample of things to Observe. We simple cannot say what Planets outside our Solar System are like, though we have begun detecting many. Since objects like Planets do not emit Light like stars do we cannot detect them so easily. Even those Planets we have discovered are limited by our methods of detection (noticing the “wobble” they cause in their parent star, which tends to favor Massive planets), and so does not give us a realistic sampling.
Since our Telescopes can only be built so big with our current technology, we can only “resolve” objects so far away with the accuracy we want. Also due to effects in the Earths atmosphere we have learned that ground based telescopes cannot provide us with as accurate of an Image as Space based observations. However, it is very costly and difficult to send telescopes into space, and there the size issue is of even greater concern.
Perhaps the most interesting of Astronomers limitations is in Light itself. Remember light travels at a certain speed (3,000 million meters per second) which is still overwhelmingly slow in Astronomical terms. It takes light over 4 years to reach us from the Sun’s nearest neighbor. In reality the Light that we see at Night is many, many years old. For all we know the stars that we see are no longer there, we wouldn’t know for Years if something happened to them. This has created the Idea that Astronomers “look back in Time”, what we see is things that have long since been. This also means that we can only “see back” so far, to the beginning of the Universe in fact. Which is another one of those Mind Boggling ideas.
So keep in mind how little it is that we know about the Universe, especially as technology grows and some of these limitations become Obsolete.