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Lonely ‘homeless’ planet found for the first time

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Re: Lonely ‘homeless’ planet found for the first time

#31

Post by CapitalistCartr »

MrMember wrote: post #11
GotAnyMegadeth wrote: post #4

Earlier quoted context omitted.

I read this brilliant short story once where the Earth had been 'stolen' by a massive rogue planet (the earth started to orbit it instead of the sun). A family had survived by building a air tight shelter and having a constant fire burning. They had to go out to fill up buckets with frozen oxygen to bring back and defrost.

A Pail of Air http://www.baenebooks.com/chapters/0743498747/0743498747___6...

That is one creepy story. I don't know if the orbital mechanics would work that way, but its a good story anyway.

Re: Lonely ‘homeless’ planet found for the first time

#32

Post by codewright »

jws wrote: post #24
doctorpangloss wrote: post #3

These planetars stoke the scifi imagination. They are the perfect hideaway for a fleeing civilization... or deadly weapon. What kind of life could exist on a planet without a star? Even when the scientific payoff is limited, the payoff to the imagination is immense.

In Passages in the Void [1], these planets are the only places the machines were willing to reincarnate humanity after deciding that stars were too dangerous, having suffered the anguish of their humans being extinguished by our own Sun. [1] A series of short stories by a Roger Williams, tagged localroger on kuro5hin, wrote back in the day. I gathered the parts together into an ePub suitable for iBooks. I'm checking…

Prime Intellect was rough on my psyche, but a good experience.

Re: Lonely ‘homeless’ planet found for the first time

#33

Post by JoeAltmaier »

MrMember wrote: post #11
GotAnyMegadeth wrote: post #4

Earlier quoted context omitted.

I read this brilliant short story once where the Earth had been 'stolen' by a massive rogue planet (the earth started to orbit it instead of the sun). A family had survived by building a air tight shelter and having a constant fire burning. They had to go out to fill up buckets with frozen oxygen to bring back and defrost.

A Pail of Air http://www.baenebooks.com/chapters/0743498747/0743498747___6...

Yeah; the Earth would remain warm for millennia -its 55 degrees underground only a few feet all year around. I always wondered, why didn't these people just live in a basement or underground garage or cave or something? Would have massively simplified their lives.

Re: Lonely ‘homeless’ planet found for the first time

#34

Post by eru »

k3n wrote: post #22
btilly wrote: post #17

Earlier quoted context omitted.

The core of planets do not remain hot for billions of years based on their formation. They remain hot because they have radioactive material that continues to generate heat. Before the discovery of radioactivity invalidated the calculation, the fact that the Earth's interior is still hot was used by Lord Kelvin to set an upper limit of 40 million years for the Earth's age.

That's not the case for Earth though, is it? I had thought it was the tremendous pressures that kept the internal core molten. If it was radiation wouldn't it be enough to destroy us living in such close proximity? I am barely qualified to call myself even an amateur astronomer, so sorry if I've misinterpreted anything. edit: re-reading the passage, it sounds like it's a combination of both (bottom of p.245, 246).

> If it was radiation wouldn't it be enough to destroy us living in such close proximity?

Different kinds of radiation differ by how deep they penetrate matter. Simplifying a bit you can imagine that for every atom the radiation passes, there's a probability that it interacts / gets absorbed.

Radiation that passes thousands of kilometres of rock without interaction will have a rather low probability of interacting with a mere metre (or so) of human.

Re: Lonely ‘homeless’ planet found for the first time

#35

Post by ComputerGuru »

Can someone explain to me how this would be termed a planet?

Doesn't the very definition of planet imply rotation around a star or other celestial object?

The BBC article is a little better: http://www.bbc.co.uk/news/science-environment-20309762 And it links to the actual paper: http://arxiv.org/abs/1210.0305

Re: Lonely ‘homeless’ planet found for the first time

#36

Post by jlgreco »

scrumper wrote: post #16

Looks like it was detected in the infrared. The article is a bit light on detail, but on the face of it it's an absolutely astonishing achievement to detect a planet-sized body with an earth-based optical telescope.

Apparently the atmospheric absorption of infrared is pretty decent for ground-based observation. Atmospheric seeing in the near-infrared is still a concern though.

Re: Lonely ‘homeless’ planet found for the first time

#37

Post by wcoenen »

rpm4321 wrote: post #10
ichabodcole wrote: post #8

Would anyone like to explain why this planet would have a temperature of 400C (I was picturing it being really cold)? Is this because of its mass/size, more related to its gaseous composition or both?

It's a brown dwarf: http://en.wikipedia.org/wiki/CFBDSIR2149-0403

I think that the news here is that is has been determined that it is not a brown dwarf. See the paper[1] for more details. Though I'm not sure why the distinction between giant planet vs cold tiny star is so important.

[1] http://arxiv.org/abs/1210.0305

Re: Lonely ‘homeless’ planet found for the first time

#38

Post by dalke »

ComputerGuru wrote: post #35

Can someone explain to me how this would be termed a planet? Doesn't the very definition of planet imply rotation around a star or other celestial object? The BBC article is a little better: http://www.bbc.co.uk/news/science-environment-20309762 And it links to the actual paper: http://arxiv.org/abs/1210.0305

There are two "planet" definitions, depending on if the object in question is in the solar system or outside. The terminology for the later is not as well settled. You might see "free floating planet" or "rogue planet" or the more general term "planetary-mass object" (or PMO or planemo). (The actual paper uses 'free floating planet' and 'planetary-mass object'.)

In any case, if the official position is that a "dwarf planet" is not a planet then it's not hard to see that a "free floating planet" need not be a "planet."

Re: Lonely ‘homeless’ planet found for the first time

#39

Post by dalke »

JoeAltmaier wrote: post #33
MrMember wrote: post #11

Earlier quoted context omitted.

A Pail of Air http://www.baenebooks.com/chapters/0743498747/0743498747___6...

Yeah; the Earth would remain warm for millennia -its 55 degrees underground only a few feet all year around. I always wondered, why didn't these people just live in a basement or underground garage or cave or something? Would have massively simplified their lives.

Those who did likely died. "Pa says that all sorts of cliffs and buildings toppled, oceans slopped over, swamps and sandy deserts gave great sliding surges that buried nearby lands."

Re: Lonely ‘homeless’ planet found for the first time

#40

Post by JoeAltmaier »

dalke wrote: post #39
JoeAltmaier wrote: post #33

Earlier quoted context omitted.

Yeah; the Earth would remain warm for millennia -its 55 degrees underground only a few feet all year around. I always wondered, why didn't these people just live in a basement or underground garage or cave or something? Would have massively simplified their lives.

Those who did likely died. "Pa says that all sorts of cliffs and buildings toppled, oceans slopped over, swamps and sandy deserts gave great sliding surges that buried nearby lands."

...and then it stopped. And then they could have moved underground. Even in their own neighborhood (in a city) I imagine there were basements.
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