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What’s past outer house? – Siah, age 11, Fremont, California
Proper above you is the sky – or as scientists would name it, the environment. It extends about 20 miles (32 kilometers) above the Earth. Floating across the environment is a combination of molecules – tiny bits of air so small you absorb billions of them each time you breathe.
Above the environment is house. It’s referred to as that as a result of it has far fewer molecules, with plenty of empty house between them.
Have you ever ever puzzled what it might be wish to journey to outer house – after which preserve going? What would you discover? Scientists like me are capable of clarify a variety of what you’d see. However there are some issues we don’t know but, like whether or not house simply goes on eternally.
Planets, stars and galaxies
Originally of your journey by house, you would possibly acknowledge a few of the sights. The Earth is a part of a gaggle of planets that each one orbit the Solar – with some orbiting asteroids and comets blended in, too.
Mark Garlick/Science Picture Library by way of Getty Photographs
You would possibly know that the Solar is definitely simply a mean star, and appears larger and brighter than the opposite stars solely as a result of it’s nearer. To get to the following nearest star, you would need to journey by trillions of miles of house. In the event you might experience on the quickest house probe NASA has ever made, it might nonetheless take you hundreds of years to get there.
If stars are like homes, then galaxies are like cities full of homes. Scientists estimate there are 100 billion stars in Earth’s galaxy. In the event you might zoom out, manner past Earth’s galaxy, these 100 billion stars would mix collectively – the best way lights of metropolis buildings do when considered from an airplane.
Not too long ago astronomers have discovered that many and even most stars have their very own orbiting planets. Some are even like Earth, so it’s potential they may be dwelling to different beings additionally questioning what’s on the market.
Michael Miller/Stocktrek Photographs by way of Getty Photographs
You would need to journey by thousands and thousands of trillions extra miles of house simply to succeed in one other galaxy. Most of that house is nearly utterly empty, with just some stray molecules and tiny mysterious invisible particles scientists name “darkish matter.”
Utilizing large telescopes, astronomers see thousands and thousands of galaxies on the market – they usually simply preserve going, in each path.
In the event you might look ahead to lengthy sufficient, over thousands and thousands of years, it might seem like new house is step by step being added between all of the galaxies. You may visualize this by imagining tiny dots on a deflated balloon after which eager about blowing it up. The dots would preserve shifting farther aside, identical to the galaxies are.
Is there an finish?
In the event you might preserve going out, so far as you wished, would you simply preserve passing by galaxies eternally? Are there an infinite variety of galaxies in each path? Or does the entire thing finally finish? And if it does finish, what does it finish with?
These are questions scientists don’t have particular solutions to but. Many suppose it’s possible you’ll simply preserve passing galaxies in each path, eternally. In that case, the universe could be infinite, with no finish.
Some scientists suppose it’s potential the universe would possibly finally wrap again round on itself – so in case you might simply preserve going out, you’ll sometime come again round to the place you began, from the opposite path.
A technique to consider that is to image a globe, and picture that you’re a creature that may transfer solely on the floor. In the event you begin strolling any path, east for instance, and simply preserve going, finally you’ll come again to the place you started. If this have been the case for the universe, it might imply it’s not infinitely large – though it might nonetheless be larger than you possibly can think about.
In both case, you could possibly by no means get to the top of the universe or house. Scientists now take into account it unlikely the universe has an finish – a area the place the galaxies cease or the place there could be a barrier of some type marking the top of house.
However no one is aware of for positive. The way to reply this query will have to be found out by a future scientist.
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This text has been up to date to appropriate the distances to the closest star and galaxy.
Jack Singal doesn’t work for, seek the advice of, personal shares in or obtain funding from any firm or group that will profit from this text, and has disclosed no related affiliations past their tutorial appointment.