Dr. Universe is back with a group of junior scientists from Palouse Prairie Charter School to learn about space. Students from the fourth-grade class in Moscow, Idaho help Dr. Universe answer how we know there are planets outside our solar system and what the universe actually is. If you like thinking about multiverses, black holes and the potential for life outside Earth, this is the episode for you!
A big thank you to Northwest Public Broadcasting for help with recording!
You can find sources for space information in the transcript.
As always, submit burning questions at askdruniverse.wsu.edu. Who knows where your questions will take us next.
Dr. Universe is back with a group of junior scientists from Palouse Prairie Charter School to learn about space. Students from the fourth-grade class in Moscow, Idaho help Dr. Universe answer how we know there are planets outside our solar system and what the universe actually is. If you like thinking about multiverses, black holes and the potential for life outside Earth, this is the episode for you!
A big thank you to Northwest Public Broadcasting for help with recording!
You can find sources for space information in the transcript.
As always, submit burning questions at askdruniverse.wsu.edu. Who knows where your questions will take us next.
Dr. Universe
Hey, cool cats. I'm Dr. Universe, and if you're anything like me, you have lots of big questions about our world. You know, I get a lot of questions from young scientists, and the other day I got a phone call from Palouse Prairie Charter School.
Renee Hill
Hi, Dr. Universe? It's Renee Hill. Our fourth grade crew was wondering if you could use any help answering some of your science questions.
Dr. Universe
Answering all these questions is a big job for one cat. That would be amazing. Let's do it. I'll send these questions soon. Thanks so much!
Renee Hill
Bye, Dr. Universe.
Dr. Universe
On this episode, you'll hear from our fourth grade scientists as they help us investigate some cool science questions from kids. Let's get started. Ella, age 9 in Colorado asked, "How do we know there are planets outside of our solar system?" Here's Stanley.
Stanley
A planet that is outside our solar system is called an exoplanet. The first exoplanet was discovered in the 1990s. And now there are almost 5,000 confirmed exoplanets. Some are bigger than Jupiter. But how did we discover that they existed? The simple answer is that we've seen stars blink, which means that a planet in orbit around that star may have passed in front of it. One of the main ways we find exoplanets is with telescopes. Here's Lauren to tell us more about telescopes.
Lauren
One of these is called the Hubble Space Telescope, named after Edwin Hubble. The idea for the Hubble telescope emerged in the 1940s, and the Hubble telescope was built and launched in 1990 -- more than 30 years after Hubble's death. This 43 1/2 foot long telescope was used to discover more planets and stars beyond our solar system. The Hubble Space Telescope helped prove the exoplanets did indeed exist. Russell, can you tell us about another telescope that helps us find exoplanets?
Russell
The Kepler Space Telescope was also designed to look for other earth-like planets orbiting other stars in our region of the Milky Way. The Kepler telescope was first launched in 2009 and watched the Cygnus constellation for four years. It surveyed more than half a million stars and found thousands that blinked repeatedly and changed in brightness, following a constant pattern. When they were looking at a star, and it blinked, they knew that something was passing in front of it, temporarily blocking the star's light. This blinking led the Kepler telescope to discover 2,662 exoplanets in one tiny bit of space. Hey, Ronan. Could you tell us some fun facts about exoplanets?
Ronan
We don't know how many exoplanets are out there, but so far NASA scientists have confirmed the existence of 4,903 exoplanets and 3,681 stars with planets. They have also discovered another 8,414 planets that have yet to be confirmed. In fact, scientists think that most stars have at least one planet based on the data they find by the Kepler telescope. There could possibly be 40 billion earth-like planets orbiting inhabitable zones around sun-like stars. That means not only are there a lot of exoplanets in our galaxy, but highly likely there's life on other planets. They have also discovered another 8,414 planets that have yet to be confirmed.
Dr. Universe
So, fourth graders, do you think there's life out there on other planets?
Students
Yes.
Dr. Universe
Now here's Mira to wrap it all up.
Mira
In summary, how we know there are more planets outside our solar system is that we've observed stars blinking, and it's because other exoplanets are passing between the observer and the star. There's still so much more to discover, and scientists are making new discoveries every day.
Dr. Universe
They sure are. Thanks for your help with that big question. Here's the next one. Maneet, age 9, in California wrote in, "Dr. Universe, What exactly is the universe?" Logan, what did you find out?
Logan
Well, simply speaking, the universe contains everything. The universe contains stars, black holes, solar systems, galaxies, and a lot of space. Humans have discovered so much in our short lifetime. There's still much more to discover. While we were researching, we were wondering about the difference between a universe, a galaxy and a solar system.
Julia
I can help with that.
Logan
Thanks, Julia.
Julia
The universe is made of galaxies, and every galaxy is composed of solar systems. Every solar system has at least one star made up of gas and dust that gives off heat and light and planets that orbit around the star that are held together by gravity. Galaxies have several billion stars. The exact number of stars in the entire universe is unknown, and astronomers continue to study the stars to estimate how many there are in the universe. Each of the solar systems within galaxies are separated by huge areas of empty space. This space between stars is called interstellar space. And there are huge areas of space between galaxies called intergalactic space.
Before we get lost in all that space, let's start right here with our planet Earth. Think about how big our planet Earth is. It's huge. If you wanted to walk the full length of equator, you'd have to walk 24,901 miles. However, planet Earth is actually like one tiny speck of dust in the entire universe. Earth is only one planet in our solar system. And our solar system is only one of the 3,200 solar systems in our galaxy, the Milky Way. The Milky Way is part of over 30 other galaxies called the Local Group, and there may be 100 billion galaxies in the universe. So even though our Earth seems huge, we are just living on one tiny planet in a universe so big that it is difficult for our human minds to comprehend.
Dr. Universe
Wow, the universe is really hard to comprehend sometimes.
Julia
Yeah, and gravity is what holds everything together. Solar systems, galaxies and the entire universe are held together by gravity. Anything with mass has gravity, and gravity keeps objects in orbit or following one path around a central object. Just like Earth and the other planets in our solar system orbit around the sun, all the solar systems in the Milky Way orbit around the center of the galaxy called the Galactic Center. Everything in the Milky Way orbits around the Galactic Center, which is a supermassive black hole. And scientists believe that there's a supermassive black hole at the center of all large galaxies.
Student
Julia, Did you know that there is a theory that our universe might actually be inside a massive black hole? Black holes are one of the biggest mysteries in our universe at this time. A black hole is an object that has such a strong gravitational pull that if something gets pulled in, it would not be able to get out. Not even light or a smaller black hole. A cool fact is that if you get sucked into a black hole, you get spaghettified. Getting spaghettified is when you stretch out like spaghetti and time slows down almost to a complete stop. A black hole is formed when a star that has a core with three times more mass than our sun collapses under its own weight. The collapse causes a supernova explosion, which is the explosion of a star and the biggest explosion we know. After the explosion, the crushed core will collapse again, and a black hole will form. There are about 40 quintillion black holes in our universe.
Dr. Universe
Wow, our universe is an amazing place. I'm curious about how it formed. Maybe some of our listeners are curious too. Solveig, what can you tell us about the beginning of the universe?
Solveig
Scientists have spent a lot of time studying all these mysteries of our universe. One of these mysteries is how did the universe even form. The Big Bang is a theory that astronomers use to explain how the universe began. The Big Bang was the beginning of time, our universe and everything you or I know. The Big Bang started as a small, dense fireball. It started to swell and expand about 13.8 billion years ago, causing energy to spread. This caused the universe to start to form. The universe has changed by expanding at just under 70 kilometers per second per mega parsec. Mega parsecs are used to measure the distance between galaxies and the expansion of the universe in the same way that astronomical units are used to measure the distance between the sun and other planets in our solar system.
Dr. Universe
So, we know how fast the universe is expanding. But how does it work?
Solveig
Well, space itself is expanding, taking clusters of galaxies along with it. Imagine it like this: you have a long rubber band with dots on it. The rubber band represents the universe and the dots are galaxies. Now as two people pull the edge of the rubber band in opposite directions, the dots become further apart. That's how we can imagine how space is expanding. In conclusion, without the Big Bang, there would be no universe, which means nothing at all. You and I would not exist if it wasn't for the Big Bang. Scientists don't know for sure what existed before the Big Bang, but many are starting to try to figure it out. Did you know that there possibly other universes out there?
John
Oh, Solveig. I can tell you about multiverses.
Solveig
Okay, John.
John
Well, one idea is the cosmic inflation theory that was developed by physicist Alan Guth. This theory proposes that in the first fraction of a second after the Big Bang, the universe expanded rapidly and formed new universes. The theory of multiverses is backed by every single piece of evidence that we have. So there is a 99.9% chance they do exist. Multiverses continue to be a very big mystery in our universe that a lot of scientists are studying. And humans have yet to visit another universe.
Student
So when someone asks, "What exactly is the universe?" you might just say, "The universe is exactly everything."
Dr. Universe
That's a wrap on this episode friends. Thanks so much for joining us on this special edition of the Ask Dr. Universe podcast featuring fourth grade scientists at Palouse Prairie Charter School.
Student
And big thanks to Northwest Public Broadcasting for helping us record and to Dr. Julie Menard at Washington State University for fact checking the science. We are grateful for the helpful, informative resources from NASA, USGS, the Smithsonian Scientific American and universities around the world. You can find a list of our sources in the transcript.
Dr. Universe
As always, kids can submit science questions at askdruniverse.wsu.edu. That's a-s-k d-r u-n-i-v-e-r-s-e dot w-s-u dot e-d-u. Who knows where your questions will take us next.
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Sources:
Nasa
USGS
National Geographic
The Smithsonian
Scientific American
Universities