Jack Singal, University of Richmond
What is beyond outer space? – Siah, 11, Fremont, California
Just above you is the sky, or, as scientists would say, the atmosphere. It extends about 32 km above the Earth. Floating around the atmosphere is a mixture of molecules: small pieces of air so small that they consume billions of them every time you breathe.
Above the atmosphere is space. It is so called because it has far fewer molecules, with a lot of empty space between them.
Have you ever wondered what it would be like to travel into outer space and then continue? What would you find? Scientists like me are able to explain a lot of what you would see. But there are some things we don’t know yet, such as whether space continues forever.
Planets, stars and galaxies
At the beginning of your space trip, you may recognize some of the views. Earth is part of a group of planets orbiting the Sun, with some asteroids and comets orbiting also mixed.
You may know that the sun is actually just an average star and that it looks bigger and brighter than the other stars just because it is closer. To get to the next nearest star, you would have to travel through billions of miles of space. If we could go with the fastest spacecraft NASA has ever made, it would still take you thousands of years to get there.
If the stars are like houses, galaxies are like cities full of houses. Scientists estimate that there are 100 billion stars in the Earth’s galaxy. If you could get far away, far beyond the Earth’s galaxy, these 100 billion stars would merge, as do the lights in city buildings when viewed from an airplane.
Astronomers have recently learned that many or even most stars have their own orbiting planets. Some are even like the Earth, so it is possible that they may be home to other beings who are also wondering what is out there.
You would have to travel through billions of miles more space just to get to another galaxy. Most of this space is almost completely empty, with only a few lost molecules and small mysterious invisible particles that scientists call “dark matter.”
Using large telescopes, astronomers see millions of galaxies out there, and move forward, in all directions.
If it could be looked at long enough, for millions of years, it would seem that a new space is slowly being added between all the galaxies. You can visualize it by imagining small dots on a deflated balloon and then thinking about flying it. The points would stay farther away, as do the galaxies.
Is there an end?
If you could get out, as far as you wanted, would you keep going through the galaxies forever? Are there an infinite number of galaxies in all directions? Or, finally, is it all over? And if it ends, what does it end with?
These are questions that scientists do not yet have concrete answers to. Many think it is likely that galaxies will continue to pass in all directions, forever. In this case, the universe would be infinite, without end.
Some scientists think that it is possible that the universe may end up rolling on itself, so if we could keep going out, one day you will return to the place where you started, from the other direction.
One way to think about it is to imagine a world and imagine that you are a creature that can only move on the surface. If you start walking in any direction, for example, to the east, and just keep going, you will finally get back to where you started. If this were the case with the universe, it would mean that it is not infinitely large, although it would be even larger than you can imagine.
In any case, you could never reach the end of the universe or space. Scientists now believe that the universe is unlikely to have an end: a region where galaxies stop or where there would be a barrier of some kind that marks the end of space.
But no one knows for sure. The future scientist will have to figure out how to answer this question.
This article has been updated to correct distances to the nearest star and galaxy.
This article is republished from The Conversation under a Creative Commons license. Read the original article.
Conclusion: Have you ever wondered what it would be like to travel into outer space and move on? What would you find? Scientists are able to explain a lot of what you would see. But there are some things we don’t know yet, such as whether space continues forever.