Godzilla of earths
There is a new class of planet out
there that astronomers are calling the "mega-Earth". It is an object with a hard surface like our own world but much, much
bigger. The necessity for the new designation follows the discovery of a planet which
has a mass some 17 times that of Earth. Known as Kepler-10c, it orbits a star about 560 light-years away. Scientists
described its properties at an American Astronomical Society meeting in
Boston.
They confess it is something of a head-scratcher. Theorists had always thought that any planet that large would pull so much
hydrogen on to itself that it would look more like a Neptune or a Jupiter."The proper way to call it is something bigger than a 'super-Earth, so how about 'mega-Earth," Prof Dimitar Sasselov, of the Harvard-Smithsonian Center for Astrophysics (CfA), told reporters. He also used the phrase, "the Godzilla of Earths!".
Kepler-10c, as the name suggests, was detected by the US space agency's Kepler telescope. This finds new worlds by looking for the tiny dip in light as they pass in front of their parent stars.
The technique gives a diameter - in this case, 29,000km, or just over two times the width of Earth - but not a mass. For that, astronomers looked at 10c with the Harps-North instrument on the Telescopio Nazionale Galileo in the Canary Islands. It extracts a mass measurement by examining the gravitational interaction between the planet and its host star. Combined with the diameter, the mass number showed that Kepler-10c cannot be a gaseous world but must comprise very dense material.
"It's 17 - in fact, it's more than 17 - Earth masses, and that brings the density to 7.5 grams per cubic centimetre, which is a lot more than what we know of rock here on Earth (5.5g/cm3)," said Prof Sasselov.
"But remember, this is a very massive planet, which means those same minerals are highly compressed. So, what you see in the density is mostly due to compression rather than different composition. The composition comes out as being a combination of rocks and some volatiles, probably 5-15% at most of water."
Interestingly, the age of the host star is about 11 billion years old, which is early in the evolution of the Universe when generations of exploding stars did not have long to make the heavy elements needed to construct rocky planets.
"Finding Kepler-10c tells us that rocky planets could form much earlier than we thought. And if you can make rocks, you can make life," says Prof Sasselov.
Aunt Jeannie ,
ReplyDeleteUntil somebody lands on the White House lawn in a space ship and says take me to your leader. That will happen before we become enlightened enough to realize that our survival lies out among the stars and not here. Even if there is no meteoric extinction event we will be living on a burned out cinder of our own making. Crops will be impossible to grow and the water to drink. We are running out of water , check California out .
The pursuit of knowledge is a mute point if we never look beyond the solar system to fashion our future. If we had any sense we would forget borders and conflicts and concentrate on our mutual education, survival, benefit, and futures.
To take an Einstein perspective, at the surface of a large diameter planet, the surrounding curvature of space would presumably be less, therefore less gravitational "force".
Larger diameters for the same amount of mass would lower the gravitational effect, not increase it. So actually if the mass were same as earth, just the diameter doubled, it would be something well less than 1 times the gravity of earth , not 4 times. But the mass is actually more dense, not less, so the two offset, apparently to the estimate given in the article.
Thank you so much aunt Jeannie for this post , we are learning so much . We will buy you a ticket on a flight with us . Love you .
Wrote by Jonny and Chris
Three cheers for the junior scientists!!!
ReplyDeleteYou said so many things that I believe also. You guys are so smart. I know I can learn a lot from you.
If all the countries in the world would co-operate and work with each other, we could do such great things. We need to think about the future not just the here and now.
I hope those very wise words you put in your letter to me are part of your debate material because I thought they were wonderful.
I don't think this new mega planet is conducive to life because of the density of all the elements upon it. And the atmosphere may be more hydrogen than nitrogen (we need 78%) and oxygen (we need at least 21%).
But I know they will keep searching because scientists are very devoted to their research, just like Jonny and Chris.
Luv you guys ( I'll be waiting for that ticket)