Recipe for extra-solar earths found but oceans love super earths better

phys.org...

"Our solar system is not as unique as we might have thought," says lead author Courtney Dressing of the Harvard-Smithsonian Center for Astrophysics (CfA). "It looks like rocky exoplanets use the same basic ingredients."

phys.org...

She found that planets two to four times the mass of Earth are even better at establishing and maintaining oceans than our Earth. The oceans of super-Earths would persist for at least 10 billion years (unless boiled away by an evolving red giant star).

Interestingly, the largest planet that was studied, five times the mass of Earth, took a while to get going. Its oceans didn't develop for about a billion years, due to a thicker crust and lithosphere that delayed the start of volcanic outgassing.

"This suggests that if you want to look for life, you should look at older super-Earths," Schaefer says.

Sasselov agrees. "It takes time to develop the chemical processes for life on a global scale, and time for life to change a planet's atmosphere. So, it takes time for life to become detectable."

the upshot is for earth-like planets those of similar size are most likely made out of the same stuff. and for places where life has the longest chance to evolve look for super earths.

a reply to: stormbringer1701

Very cool. I wonder though, on a super earth the gravity would be higher would life evolved on such a planet ave a tendency to be bigger or smaller. I think the possibility of any advanced life on a super earth would be less likely to be exploring space because of the physics involved for escape velocity.

Anyway, S&F for the find it will fuel my imagination for a while.

originally posted by: Grimpachi
a reply to: stormbringer1701

Very cool. I wonder though, on a super earth the gravity would be higher would life evolved on such a planet ave a tendency to be bigger or smaller. I think the possibility of any advanced life on a super earth would be less likely to be exploring space because of the physics involved for escape velocity.

Anyway, S&F for the find it will fuel my imagination for a while.

well, what if life never left the oceans because the whole surface is covered? Astronauts train in those 300 pound spacesuits in swimming pools for a reason. even if there were some land the farther away from the center mass of the planet the smaller gravity will be this means gravity on super earths isn't as large as you'd expect. it can be quite large though; so expect anything in the tree niche to be a shrub and expect no large terrestrial animals like elephants, rhinos, hippos and so forth. avian niche animals might be rarer. or expect gas bag animals. the atmosphere is likely denser so it would be easier for balloons to float. basically more common gases would be lighter than air than on earth. in fact if there were big floating gas bag animals they would likely have symbiotic relations with other creatures. avian flyers or gliders could use the giant floaters as elevators to high altitude to assist them in getting airborne.

a reply to: stormbringer1701

Astronauts train in those 300 pound spacesuits in swimming pools for a reason.

They train in pools with neutral buoyancy to simulate the weightless environment of space.

if there were some land the farther away from the center mass of the planet the smaller gravity will be this means gravity on super earths isn't as large as you'd expect.

It doesn't work that way. Even if they find a really tall mountain the mountain itself is mass which would increase the gravity for that area. On earth there are areas where gravity fluctuates.

Now the spin of a planet does affect the gravity especially at the equators here it is kind of negligible of course there is a bulge at the equator as well adding mass directly below.

The equations of it all is beyond me.

originally posted by: Grimpachi





They train in pools with neutral buoyancy to simulate the weightless environment of space.

yes which means gravity is not relevant to things floating in oceans (not on the floor)

It doesn't work that way. Even if they find a really tall mountain the mountain itself is mass which would increase the gravity for that area. On earth there are areas where gravity fluctuates.

Now the spin of a planet does affect the gravity especially at the equators here it is kind of negligible of course there is a bulge at the equator as well adding mass directly below.

The equations of it all is beyond me.

actually is does work that way. that's what the equation says. the force of gravity drops off as the distance between the center of mass of the planet (mass one) and the center of mass of whatever is being attracted to the planet (mass two.)

en.wikipedia.org...

a reply to: stormbringer1701

You do realise that differences in the local geology and changes in the density of rock underneath you or the presence of mountains nearby can have an effect on the gravitational force.

More mass underfoot if comparable to the same density as local surroundings equates in higher gravity.

You can't say that just because there is a highpoint like a mountain gravity would be less there. Imagine if that mountain was primarily composed of lead or gold then that point would have the highest gravity.

Here is a gif of Earths mapped gravity. Some of the heaviest points are unexpected. Mass and density must be factored when considering those things.

originally posted by: Grimpachi
a reply to: stormbringer1701

You do realise that differences in the local geology and changes in the density of rock underneath you or the presence of mountains nearby can have an effect on the gravitational force.

More mass underfoot if comparable to the same density as local surroundings equates in higher gravity.

You can't say that just because there is a highpoint like a mountain gravity would be less there. Imagine if that mountain was primarily composed of lead or gold then that point would have the highest gravity.

Here is a gif of Earths mapped gravity. Some of the heaviest points are unexpected. Mass and density must be factored when considering those things.

yes. as any gravitic geoid map will show. However; on average because of the universal law of gravitational attraction the power of gravity drops off with the square of the distance between the centers of the gravitating masses.

as to the mountain thing:

www.newton.dep.anl.gov...

you weigh less on a mountain top because you are further from the center of earth's gravity despite the extra mass under you from the mountain.

www.physlink.com...

Our weight is defined as the force that we exert due to our mass. This force is equal to GMm/r2, where G is a constant, M is the mass of the earth, m is your mass and r is the distance between the center of the earth and you. As you are nearer to the center of the Earth in death valley r will be smaller thus making the force larger, so you would weigh more in Death Valley than on Mount Everest. However the difference is so small that it cannot be measured easily. Atmospheric pressure will not affect your weight. The atmospheric pressure will be greater in Death Valley however, as the air is more dense there than on top of Mount Everest.

a reply to: stormbringer1701

Did you understand what they were saying?

Did you read the entire thing?

If you did, did you somehow miss this from your source?

Yes, any object with mass attracts any other object with mass by gravitation. If you stand on a tall mountain, yes, the downward pull of gravity will be greater than if you were in a valley. This outweighs (pun intended) the effect of increasing the distance from the center of the earth, which as you noted would reduce the gravitational force.


Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

Look you can believe it or not but that is from your source.

Maybe you got a little confused because the problem factored in being in a valley with mountains on the sides exerting a force.

originally posted by: Grimpachi
a reply to: stormbringer1701

Did you understand what they were saying?

Did you read the entire thing?

If you did, did you somehow miss this from your source?

Yes, any object with mass attracts any other object with mass by gravitation. If you stand on a tall mountain, yes, the downward pull of gravity will be greater than if you were in a valley. This outweighs (pun intended) the effect of increasing the distance from the center of the earth, which as you noted would reduce the gravitational force.


Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois

Look you can believe it or not but that is from your source.

Maybe you got a little confused because the problem factored in being in a valley with mountains on the sides exerting a force.

i did see that. yes. but that reply and a few others was wrong. it's a thread (that first link posted in haste); and any thread will have people in it that do not know what they are talking about but still feel the need to post.. that's why i added the second link; to give the definitive answer.

a reply to: stormbringer1701

So to back up one blog you post another blog which also states.

The formula is easily derived by making assumptions about the mass density of the earth.

I hope you remember I said these things are dependent and mass and density.

Now I don't know about you but I tend to favor the opinions of those who have Phds or masters over students from Tiffin Girls' School.

Seeing as how both are from boards/blogs don't you think the ones who already earned their degrees may know more than a student?

Calculating gravity isn't as easy as applying a mathematical formula from the center you also need to know the density and material beneath you.

Gravity anomaly maps (see globe below) show how much the Earth’s actual gravity field differs from the gravity field of a uniform, featureless Earth surface. The anomalies highlight variations in the strength of the gravitational force over the surface of the Earth. Gravity anomalies are often due to unusual concentrations of mass in a region. For example, the presence of mountain ranges will usually cause the gravitational force to be more than it would be on a featureless planet — positive gravity anomaly. Conversely, the presence of ocean trenches or even the depression of the landmass that was caused by the presence of glaciers millennia ago can cause negative gravity anomalies.

earthobservatory.nasa.gov...

Below is a map of mapped gravity fluctuations. Notice many higher gravity fields especially in South America mountain ranges.

it is not just in blogs though. its in school curriculums. i remember being taught that in high school.

look it's not surprising to me. there are people who swear up and down for pages that time dilation works bass ackwards from the way it does; too.

a reply to: stormbringer1701

Water is mass, mass is essential for gravity. Unfortunately gravity is a constant on earth pretty much right up until there is no more air... What is in between you and Earth isn't really what determines the effect of gravity... It's what isn't.