Exciting Space Discoveries!
Big Discoveries: Biggest Black Hole and a New Earth!
By Jason Kendall
December 7, 2011 — This week has seen an amazing pair of discoveries that boggle the imagination: the largest black hole ever found was announced … as well as a planet much like our Earth around a distant star!
First, let’s look at the biggest black hole ever found .
A black hole is a region of space where gravity is so strong that nothing can escape its pull, not even light. (That’s why they’re called “black” holes.)
Well, it’s also called a hole. But it’s not a hole like you would fall down and call for help and your helpful friends would go get the fire department and pull you out. The gravity is so strong, that if you fell in, no fire ladder would ever be able to reach you. But, it’s not like these things travel around gobbling up stars and planets and people (phew!).
Small black holes happen when a star ends its life in a dramatic supernova. The video below is a brief animation of what a supernova forming a black hole might look like.
But this black hole is REALLY big. It is so big that it’s ten times the size of our Solar System!
Now a black hole is nothing to worry about; our Sun is not near one. And the one that was found is so far away that it’s not even in our own galaxy.
It’s so far away that light, traveling at 186,000 miles per second, took over 331 million years to get here, so we see the black hole as it was 331 million years ago .
If it’s so far away, and we can’t be hurt by it, why do astronomers care about these super-sized black holes? It’s because black holes with as much stuff in them as a billion suns have influenced the way the universe grew up from infancy .
Just like you’re young (or were once young) the universe was once young, too. When the universe was younger, all the galaxies (big clouds of stars and gas and dust) were spread out. But quickly in the universe’s “Terrible Two’s” little galaxies collided to form bigger and bigger galaxies. This is how our Milky Way came to have 100 billion stars in it.
But some galaxies were the alleyway bullies, gobbling up huge amounts of other galaxies and pulling them together by their gravity. As these galaxies collided together, so did their central black holes, and those got bigger as well.
Nowadays, the biggest of these galaxies have the really largest black holes at their centers. So, as big galaxies form, they form big black holes, and it’s part of knowing the “health” of a galaxy. Like going to the doctor for your annual checkup, they always weigh you, take your height, check your ears and tongue, so with galaxies from their infancy, we check their weight, how brightly they shine, how their shape changes as they grow, and where they live with respect to other galaxies.
Checking the big black holes at the centers of lots of galaxies throughout the history of the universe is a lot like taking the heartbeat of all the galaxies in which they reside. So, by seeing how these big black holes change over cosmic time, we’re basically looking at how our universe grew up. (Baby pictures are always fun! Just ask mom and dad.)
Speaking of grown up, a new planet has been found, that’s a lot like Earth! The big planet with the not-so-exciting name “Kepler 22b” has been found around another star!
This planet does not orbit our Sun, like the Earth and Mercury and Mars and Saturn, but it orbits a star 600 light-years away. That’s 3,500,000,000,000,000 miles away!
Even going as fast as the New Horizons Spacecraft that’s on its way to Pluto , it would take over 6 million years to get there, and since you’ve been reading this article, New Horizons has gone 1,700 miles!
But that’s not what makes this new planet, Kepler 22b, so special. What makes it really exciting is that it’s about as far away from its star as the Earth is from our Sun . It’s not so close that it’s super hot like Venus and Mercury, and it’s not so far that it’s cold and frozen like Mars and the outer planets. Kepler 22b lives in the “Goldilocks Zone” where it’s not too hot and not too cold; it’s just right.
Also, this planet orbits a star much like our Sun. If you were there, it would have that same familiar yellow glow in the planet’s sky. This all means that Kepler 22b is the first planet found where liquid water might exist on its surface. This is just like our Earth, and is a requirement for finding life on another planet.
So, this planet, which is twice the size of our Earth and goes around its star in 290 days (just a little less than our year) , is massive enough to hold onto the water and make a good, thick atmosphere, so much so that its probably a water world covered in a global ocean with no dry land.
The Kepler Space Telescope has been searching for planets around other stars, and specifically for planets like this one, since 2009. It’s a telescope in space, and the rocket that launched it put it into an orbit around the Sun, following behind the Earth. The telescope just looks at the same patch of sky all the time, never wavering in its gaze. (Kepler would seriously win a staring contest!)
By looking at the same place all the time, it can see the tiny changes in the light of all the stars that are in its view. As a planet passes in front of a star, the star’s light dims just a little bit. By looking for the same dimming in a regular interval, we find the planets.
Now here’s the really cool thing, the Kepler Space Telescope is so sensitive, that it has definitely found 28 planets around other stars and has made a list of 2,326 possible planets for astronomers to check. Of those 2,326, most are like Jupiter, Saturn, Uranus and Neptune: big balls of gas with no solid surface or liquid water. But 48 of these possible planets seem to live in the “Just Right” orbits around their stars. What makes this so amazing is that not only are planets around stars seemingly fairly common, but that Earth-sized planets may be in abundance as well!
You are now officially growing up in a time when we know that there’s another Earth out there. And maybe, just maybe, one day, our great-great-great-great-great-great-great-great grandchildren will sail its seas and watch a sunrise from a different Sun!
Have questions for Jason? He’s happy to answer them! To read Jason’s previous article about Curiosity’s mission to Mars, click here.
Jason Kendall is Here There Everywhere’s writer about big news in space. He’s also the New York City Solar System Ambassador for NASA’s Jet Propulsion Laboratory and he teaches Astronomy at William Paterson University. Jason once drove 300 miles to stargaze!