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# 'Super-Earth' discovered 31 light years away

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Astronomers have announced the discovery of a large, potentially habitable world in a nearby solar system.

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Mean while, people here on our Earth still have to pay taxes and get screwed over by their respect governments.

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4 hours ago, UM-Bot said:

Astronomers have announced the discovery of a large, potentially habitable world in a nearby solar system.

Not by us unless we settle in the upper atmosphere. 6 times the size of Earth is on the "Mini-Neptune" end of things.

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Being as (relatively) close as this, it will probably be possible for for larger Earth-based telescopes, due to be deployed in the next few years, to detect signs of life from this planet, if any are there to be found. Given a mass six times that of Earth, the planet could have a dense atmosphere. This would retain more heat than in a planet receiving a similar amount of heat from its star, but with a thinner atmosphere, a case like that of Mars.  A dense atmosphere would also resist erosion by stellar winds, a very important consideration in planets that closely orbit their stars.

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2 hours ago, GLCsector3295 said:

Mean while, people here on our Earth still have to pay taxes and get screwed over by their respect governments.

How is that in any way relevant to astronomy ?

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36 minutes ago, Piney said:

Not by us unless we settle in the upper atmosphere. 6 times the size of Earth is on the "Mini-Neptune" end of things.

Thank you.  It drives me crazy when people say habitable about planets whose gravity would crush us.

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21 minutes ago, OverSword said:

Thank you.  It drives me crazy when people say habitable about planets whose gravity would crush us.

Especially when they call it a super-earth.  Makes it sound so great.  Like this only better.

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1 hour ago, Piney said:

Not by us unless we settle in the upper atmosphere. 6 times the size of Earth is on the "Mini-Neptune" end of things.

I dont think the gravity would kill someone, at least not in the short-term.

It might cause some funny looking short people with tree trunk legs.

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10 minutes ago, RabidMongoose said:

I dont think the gravity would kill someone, at least not in the short-term.

It might cause some funny looking short people with tree trunk legs.

You wouldn't last a month at constant 6 g's.  Heart attack.

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13 minutes ago, RabidMongoose said:

I dont think the gravity would kill someone, at least not in the short-term.

The atmosphere would be 6 times denser too. It would be like going to the bottom of the ocean. You would be crushed.

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45 minutes ago, OverSword said:

Thank you.  It drives me crazy when people say habitable about planets whose gravity would crush us.

and atmosphere too.

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Posted (edited)
4 minutes ago, Piney said:

The atmosphere would be 6 times denser too. It would be like going to the bottom of the ocean. You would be crushed.

Thats not enough pressure to crush someone, but if 6g would kill someone in under a month thats a problem.

Space Shuttles and Rockets subject astronauts to 5g - 6g for 20 minutes, fighter pilots up to 9g for 30 seconds. Maybe humans adapt or maybe we can increase adaption using medication. We certainly wouldnt be able to send someone at risk of thrombosis.

Edited by RabidMongoose

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We know the mass of this planet, but not its size. Thus, we do not know its density, nor its likely composition. It could be a larger version of Earth, or a smaller one of Neptune. The former possibility is more interesting, as far as life as we know it is concerned. We know nothing, at the moment, about the atmosphere of this planet, or if it even has one.

Doubtless, if life exists on this planet, it will be adapted to whatever conditions exist there, be these stronger surface gravity, greater atmospheric pressure, or otherwise.

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13 minutes ago, RabidMongoose said:

Thats not enough pressure to crush someone, but if 6g would kill someone in under a month thats a problem.

The temperature would be 4-6 times higher too. I don't think anyone would survive.

9 times Earth pressure will make CO into a super critical fluid. So 6 times would certainly collapse your lungs. If not crush your organs

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19 minutes ago, Piney said:

The temperature would be 4-6 times higher too. I don't think anyone would survive.

9 times Earth pressure will make CO into a super critical fluid. So 6 times would certainly collapse your lungs. If not crush your organs

The air pressure aint really the problem, that can be dealt with. Such as with a closed habitat. The real problems is if its too much gravity as we dont have anything to get around that yet.

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5 hours ago, OverSword said:

Thank you.  It drives me crazy when people say habitable about planets whose gravity would crush us.

Potentially habitable refers to life in general, not specifically humans.

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5 hours ago, OverSword said:

You wouldn't last a month at constant 6 g's.  Heart attack.

6x mass does not = 6x Earth gravity.

Gravity depends on mass, size and density.

Eg. A planet with twice the diameter and 8x the mass of Earth would have 2g.

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14 minutes ago, Timothy said:

6x mass does not = 6x Earth gravity.

Gravity depends on mass, size and density.

Eg. A planet with twice the diameter and 8x the mass of Earth would have 2g.

But since they are calling it a super earth then they are talking about the diameter more than the mass, right? Do they have the ability to determine the planets mass at these distances?

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This is the most relevant thing I could find with google:

A planet has mass five times that of the Earth and radius three times that of the Earth. Can you calculate its acceleration due to gravity?

The earth's acceleration due to gravity is 9.8 m/s^2 (approx). The formula of acceleration due to gravity is given by this formula -

## g=GMr 2   g=GMr2

where G is the Gravitation Constant, M is the mass of the body and r is it's radius.

From the above equation, it is clear that the acceleration due to gravity is directly proportional to the mass and inversely proportional to the square of the radius of the object. This means that if you increase the mass of the body by 5 times, the acceleration due to gravity would also increase by 5 times. And if you increase the radius by 3 times, the acceleration due to gravity would decrease by 9 times (because it's inversely proportional to the square of the radius). Thus, if you increase the mass by 5 times and at the same time increase the radius by 3 times, the new acceleration due to gravity would be 59  59 times the previous value.

So, if a planet has a mass 5 times greater than earth and radius 3 times greater than earth, it's acceleration due to gravity would be 59  59 times than that of earth.

Multiplying 5/9 by 9.8, we get g=5.45 m/s^2.

No big numbers involved, gravitation constant's value not involved.
For awesome (and weird) physics, follow my Quora Blog - Physics for Laymen

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9 minutes ago, OverSword said:

But since they are calling it a super earth then they are talking about the diameter more than the mass, right? Do they have the ability to determine the planets mass at these distances?

That depends on the method used to find it. The TESS satellite uses the photometric transit method and that does give an indication of both mass and diameter. https://en.wikipedia.org/wiki/Methods_of_detecting_exoplanets#Transit_photometry

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Posted (edited)
13 minutes ago, OverSword said:

But since they are calling it a super earth then they are talking about the diameter more than the mass, right? Do they have the ability to determine the planets mass at these distances?

Well no, they are generally talking about mass being greater than Earth, but still similar. Up to about 10x the mass of Earth I think.

And the term is not generally use to suggest it would be habitable for us. Just the mass.

Wiki explains the general definition pretty well: https://en.m.wikipedia.org/wiki/Super-Earth

So, this new planet may have around 3g. Still too much for humans to survive.

‘GJ 357 d is located within the outer edge of its star’s habitable zone, where it receives about the same amount of stellar energy from its star as Mars does from the Sun,” said co-author Diana Kossakowski at the Max Planck Institute for Astronomy in Heidelberg, Germany. “If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface.”

Without an atmosphere, it has an equilibrium temperature of -64 F (-53 C), which would make the planet seem more glacial than habitable. The planet weighs at least 6.1 times Earth’s mass, and orbits the star every 55.7 days at a range about 20% of Earth’s distance from the Sun. The planet’s size and composition are unknown, but a rocky world with this mass would range from about one to two times Earth’s size.’

So we can’t speculate much until we know more...

Edited by Timothy
Edit.
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5 hours ago, OverSword said:

This is the most relevant thing I could find with google:

A planet has mass five times that of the Earth and radius three times that of the Earth. Can you calculate its acceleration due to gravity?

The earth's acceleration due to gravity is 9.8 m/s^2 (approx). The formula of acceleration due to gravity is given by this formula -

## g=GMr 2   g=GMr2

where G is the Gravitation Constant, M is the mass of the body and r is it's radius.

From the above equation, it is clear that the acceleration due to gravity is directly proportional to the mass and inversely proportional to the square of the radius of the object. This means that if you increase the mass of the body by 5 times, the acceleration due to gravity would also increase by 5 times. And if you increase the radius by 3 times, the acceleration due to gravity would decrease by 9 times (because it's inversely proportional to the square of the radius). Thus, if you increase the mass by 5 times and at the same time increase the radius by 3 times, the new acceleration due to gravity would be 59  59 times the previous value.

So, if a planet has a mass 5 times greater than earth and radius 3 times greater than earth, it's acceleration due to gravity would be 59  59 times than that of earth.

Multiplying 5/9 by 9.8, we get g=5.45 m/s^2.

No big numbers involved, gravitation constant's value not involved.
For awesome (and weird) physics, follow my Quora Blog - Physics for Laymen

This is more relevant to the what @Timothy was explaining...

Quote

## Relationship of surface gravity to mass and radius

...

the recently discovered planet, Gliese 581 c, has at least 5 times the mass of Earth, but is unlikely to have 5 times its surface gravity. If its mass is no more than 5 times that of the Earth, as is expected,[6] and if it is a rocky planet with a large iron core, it should have a radius approximately 50% larger than that of Earth.[7][8] Gravity on such a planet's surface would be approximately 2.2 times as strong as on Earth. If it is an icy or watery planet, its radius might be as large as twice the Earth's, in which case its surface gravity might be no more than 1.25 times as strong as the Earth's.[8]

These proportionalities may be expressed by the formula:

{\displaystyle g\propto {\frac {m}{r^{2}}}}

where g is the surface gravity of an object, expressed as a multiple of the Earth's, m is its mass, expressed as a multiple of the Earth's mass (5.976·1024 kg) and r its radius, expressed as a multiple of the Earth's (mean) radius (6,371 km).[9] For instance, Mars has a mass of 6.4185·1023 kg = 0.107 Earth masses and a mean radius of 3,390 km = 0.532 Earth radii.[10] The surface gravity of Mars is therefore approximately

{\displaystyle {\frac {0.107}{0.532^{2}}}=0.38}

times that of Earth. ...

At six time Earth's mass you might guess it's

>>> 6/6**(2/3)
1.81712059283214

That's approximately 1.8 Earth.

Quote

Radial velocities discovered two more planets in the system at 9.12 (GJ 357 c) and 55.6 days (GJ 357 d), with minimum masses of 3.59+/-0.50 and 6.1+/-1 Earth masses, and an irradiation of 4.4 and 0.38 Earths irradiation, respectively. GJ 357 d receives slightly less stellar irradiation than Mars does in our own Solar System, which puts it in the Habitable Zone for its host star. GJ 357 d could not have been detected with TESS and whether it transits remains an open question.

Here we model under what conditions GJ 357 d could sustain surface habitability and present planetary models as well as synthetic transmission, reflection and emission spectra for a range of models for GJ 357 d from water worlds to Earth-like models. With Earth-analog outgassing rates, GJ 357 d would be a frozen rocky world, however with an increased CO2 level, as would be expected if a geological cycle regulates carbon dioxide concentration like on Earth, the planet models show temperate surface conditions.

If we can detect a transit of GJ 357 d, it would become the closest transiting, potentially habitable planet in the solar neighborhood. Even if GJ 357 d does not transit, the brightness of its star makes this planet in the Habitable Zone of a close-by M star a prime target for observations with Extremely Large telescopes as well as future space missions.

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2 hours ago, Golden Duck said:

That's approximately 1.8 Earth.

I always assumed that gravity would be much stronger for planet 6 times the mass of Earth. This is great tho, even much more massive planets would have similar life.

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43 minutes ago, Sir Smoke aLot said:

I always assumed that gravity would be much stronger for planet 6 times the mass of Earth. This is great tho, even much more massive planets would have similar life.

Remember, I assumed the same density as earth.

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what is really dense, is debating this topic. There is no way to reach any of these planets ever, so the topic becomes pointless/ dense. Until an actual probe can be sent to these plants to take actual photographs and make more detailed analysis then all I can really spare for these planet hunters is a slow golf clap and maybe play a tiny violin when they explain they found a possible habitable planet.

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