Ask Tappity: Science Questions for Kids > How Big is the Universe?
How Big is the Universe?
The universe is huge - but just how big is it? Watch this video to find out, or read our explanation below!
The Universe is Everything That Exists
When we talk about the universe, we’re talking about everything - Earth, the Sun, the solar system, the Milky Way galaxy, all the other galaxies, and everything else we haven’t even seen yet. In fact, it even includes things we can’t see, because the light from them hasn’t had enough time to reach us yet. It even includes things we’ll NEVER see, no matter how long we wait, because the universe is expanding faster than the light from them is traveling towards us, so it will just never reach us.
How Big is the Visible Universe?
We can measure the size of the visible universe - the amount of the universe we can see. We measure it in light years - the distance light travels in one year. Scientists estimate that the visible universe is about 92 billion light years across. For scale, the Earth is only about 8 light MINUTES from the Sun.
How Big is the Whole Universe?
Ok, well, how big is the entire universe - everything that exists, whether its light has had time to reach us or not? Well, the answer is, nobody knows! But scientists estimate that it's really, really big. A conservative estimate is that the entire universe is at least 250 times larger than the observable universe.
Space Facts for Kids
Questions about the Universe? Look no further!
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A light year is the distance light travels in one year. Even though it looks instantaneous to us, light actually takes time to travel, just like everything else. Light from the sun takes about 8 minutes to reach Earth.
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Yes! The universe is expanding all the time. Every other galaxy is rushing away from our galaxy, like dots on an inflating balloon.
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Very cold - about -454.81 degrees Fahrenheit, which is only 2 degrees above absolute zero, the coldest it's possible to be.
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If the universe is expanding, it makes sense to ask what exactly it’s expanding into. Again, no one knows, but one theory is that our universe is just one of many universes, all very far apart from one another and set in a sort of “super-universe.”
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Scientists who study space, who are called astronomers, estimate that there are at least 100 billion planets. Of these, we’ve so far confirmed just over 5,000 of them. Planets outside of our solar system are called Exoplanets. And of those, almost 60 are potentially habitable, according to NASA.
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The Milky Way Galaxy is shaped like a spiral, with multiple arms spinning around. It is around 100,000 light years across - that means if you turned on a flashlight at one end of the Milky Way, it would take the light 100,000 years to reach the other side.
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If you took everything in the Milky Way and weighed it, it would altogether weigh as much as 1.5 trillion Suns.
More Answers to Space Questions from Kids
What was the Big Bang? Could humans live on the Moon? The Tappity Astronomy Library has interactive lessons with answers to those questions and more!
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