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| Gliese 581 d (aka Cuz; a real planet for speculation | |
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| Topic Started: Jan 26 2010, 01:25 PM (3,963 Views) | |
| Canis Lupis | Jan 26 2010, 01:25 PM Post #1 |
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Dinosaurs eat man, woman inherits the Earth.
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http://en.wikipedia.org/wiki/Gliese_581_d Here in "The Habitable Zone" forum, we mostly make fictional worlds to evolve life for. The only exceptions I've seen are Europa and Mars. But in 2007, a team of Chilean scientists headed by Stephen Udry discovered a world that could actually support life outside of our solar system. Gliese 581 d is the fourth planet orbiting the red dwarf Gliese 581. For ease of typing, let's come up with a nickname for Gliese 581 and it's system. Any ideas? I'm going to make this an open project. Is anyone able to make worlds in Celestia willing to create Gliese 581 d? I know it is already on Celestia, but I would like to be able to see a hypothetical surface from space. This world, according to Stephen Udry and a lot of other scientists, is likely an ocean planet with a few sparse areas of land. So whoever does this in Celestia needs to take that into account. Now let's speculate! |
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| T.Neo | Jan 27 2010, 08:43 AM Post #16 |
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Translunar injection: TLI
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Firstly, I'd like to say how much I love and hate the idea of giving the planets in exosystems real names. The IAU has not yet seen a "need" to name exoplanets, but I think doing so for systems of interest, at least, would be best. (I mean, no one really cares about some random hot Jupiter planet that is probably totally uninteresting). But a planet that has high probability for life, even a planet like Gliese 581d, should at least get some attention. Names like "Gliese 581e" can become a tad confusing. Perhaps however, it's time to broaden the rules on planetary naming- instead of only naming them after deities from extinct religions, we can name them like we do asteroids (perhaps not as wacky. I know I would fine the concept of a planet being called James Bond utterly stupid). Gliese 581c, not 581d, was originally considered as being habitable. However, it is now thought that this planet has a "runaway greenhouse" climate, similar to the planet Venus. So it isn't probable as a home for life (or at least terran-analogue life). Gliese 581d is almost certainly covered in a worldwide ocean, hundreds or potentially even thousands of kilometers deep. So there would be no land, and probably no light-recieving seabed. Oceans that deep would form exotic allotropes of ice (not due to temperature, but rather, pressure). While it is expected for planets this large to accumulate more water then smaller (Earth-sized) planets, Gliese 581d's orbit probably migrated inwards in the distant past, so it would have accreted more water beyond where it is now. 581d is almost certainly an ocean planet, with no "surface" above or below the water that would be habitable to life. Being larger then Earth, it probably has a higher atmospheric pressure as well. This would undoubtedly be advantageous to flying or floating organisms. As for composition, I'd imagine something slightly similar to our atmosphere. Mostly nitrogen, some carbon dioxide and then oxygen. I suppose primordial trace elements (neon etc) could exist in limited amounts, kept there by the bigger gravity well. Perhaps even some hydrogen or helium, but not much. When it comes to terrestrial planet atmospheres, Nitrogen usually predominates, as does CO2. I've seen too many wacky atmospheres in spec biology projects. This thick atmosphere would probably make the ocean surface very warm. I don't see ice packs forming at the poles. Cloud cover would probably be extensive. Gliese 581d also has a very eccentric (elliptical) orbit around Gliese 581, meaning that it has potentially very violent volcanic activity. Since the volcanoes are under thousands of km of water and ice-allotrope, they probably don't pose much of a threat besides big gas bubbles... but frequent eruptions could seed the euphotic zone with nutrients, vital to life. Also, due to this orbit, Gliese 581d probably has a rotation/orbital resonance of 3:2, like our planet Mercury. This means long days, perhaps on the order of months or more for a single rotation. I haven't done the math (correctly) yet, so I don't know the exact rotational period. Due to tidal forces, it also probably doesn't have any moons (unfortunately), again similar to Venus or Mercury. From space it would probably look featureless (apart from specular reflections) and ocean-coloured, marbled with slightly more extensive Earth-like clouds. As for life evolving here, cellular life could certainly occur. Multicellular life could, as well: it'd be a far more plausible version of life on a gas-giant, due to the thicker and easier to float in medium. Flight could be done by transitioning from the water into the air- even with the higher gravity, the thick atmosphere should make flight easy. I've been working on a Gliese 581 system addon for an awesome space-flight simulator called Orbiter, and I have it pretty close to release. I'll be willing to show screenshots and pass on my texture files (provided you give me credit :P) since I currently don't have a copy of celestia nor know how to develop for it. |
| A hard mathematical figure provides a sort of enlightenment to one's understanding of an idea that is never matched by mere guesswork. | |
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| lamna | Jan 27 2010, 08:58 AM Post #17 |
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If the sea bed is covered in pressure ice then life would probably have a hard time evolving into large numbers of diverse forms. The open oceans of Earth are aquatic deserts, plenty of sunlight but hardly any nutrients, so their is little phytoplankton. And unlike earth the nutrients on Elizabeth that does sink down to the ocean floor is going to get trapped in the ice. No soil will erode from land that could feed the oceans, and there is no rock seabed deep below. If it's inhabited I expect life will be pretty rare and have rather slow metabolisms. |
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Living Fossils Fósseis Vibos: Reserva Natural 34 MYH, 4 tonne dinosaur. [flash=500,450] Video Magic! [/flash] | |
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| T.Neo | Jan 27 2010, 09:13 AM Post #18 |
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Translunar injection: TLI
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Why do you need a surface to evolve into diverse forms? Water is a pretty dense medium- you can float in it. Oceans of Earth are also deserts in another regard- sunlight. Most of our abyssal plains are biological deserts since there isn't any light. Of course, Gliese 581d isn't much of an improvement in this regard. There is no land to erode back into the sea, but the planet could be very volcanically active- many times more active then the moon Io (and if you know about Io, you'll understand what I mean by very). I could see volcanoes bringing some nutrients to the euphotic zone, at least. |
| A hard mathematical figure provides a sort of enlightenment to one's understanding of an idea that is never matched by mere guesswork. | |
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| Oceaniis | Jan 27 2010, 09:59 AM Post #19 |
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Adolescent
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Made few more calculations, and the planet top atmosphere recives only 26% of the light on earth at the average distance from the star, wich represents the most part of the year... At perihelion it have 66% and on aphelion 12%... The average distance is like earth be at 1,9AUs (mars 1,5) with earth atmosphere it would have -64ºC instead 14ºC like earth... Perihelion equivalent to 1,2AU, -10ºC; Aphelion 2,8AU, -101ºC... Increasing green house effect to 8 times the earth's GHouse, you would have the 14ºC average at the average distance, still have -37ºC at aphelion (87ºC at perihelion) You can made more experiences here just put mass=1 and distance = 1.2 for perihelion, 2.8 to aphelion and 1.9 for average, the other too, just play with them... I made a superficial calculation on the day period I it give me 32 days, which indicates to a rotation/orbital resonance of 2:1... NOTE: Since a half of the year is 33 days I'm not sure if the atmsphere would cool down 100ºC in that period... probably have some termal inercia and wouldn't reach that cold at the aphelion Edited by Oceaniis, Jan 27 2010, 07:02 PM.
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| Empyreon | Jan 27 2010, 02:13 PM Post #20 |
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Are you plausible?
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I have a knowledge of planetary physics? One thing I want to point out, though, is that atmosphere density isn't a direct result of planetary gravity (Venus shows us that). You could have a planet with low gravity and still have an atmosphere dense enough to support flyers quite easily. |
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Take a look at my exobiology subforum of the planet Nereus! COM Contributions food for thought
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| Oceaniis | Jan 27 2010, 03:03 PM Post #21 |
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Adolescent
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Also Titan have 1,5 bar at surface and only 0,14g! But in this case it wouldn't have less than 2g... it would capture a lot of gases and with a 100% water surface makes things even better, it would have a thick atmosphere I noticed another problem... it wouldn't have a magnetic field, since it spins in 33 days... there aren't any problem to creatures below the first 5m of water (in a earth like atmosphere) but flying creatures.... |
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| Empyreon | Jan 27 2010, 03:12 PM Post #22 |
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Are you plausible?
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Hmm... No magnetic field? That's an obstacle. Life would have a hard time getting away from an aquatic lifestyle. |
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Take a look at my exobiology subforum of the planet Nereus! COM Contributions food for thought
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| Holben | Jan 27 2010, 03:17 PM Post #23 |
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Rumbo a la Victoria
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If they get out of water, the radiation and damaging cosmic wind would ionise them slowly but surely. Unless the atmosphere was very thick. |
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Time flows like a river. Which is to say, downhill. We can tell this because everything is going downhill rapidly. It would seem prudent to be somewhere else when we reach the sea. "It is the old wound my king. It has never healed." | |
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| T.Neo | Jan 27 2010, 03:34 PM Post #24 |
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Translunar injection: TLI
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Actually an Earth-like atmosphere would give you a fair amount of protection from cosmic rays. I also don't see why a 33 day rotation period would mean no magnetic field... if it had an iron core, such a rotation might be enough for at least a very weak field. Venus can also be used as an example- Venus is closer to the Sun then Earth, has no magnetic field, yet has an atmosphere almots 100 times as thick. So magnetic fields are not totally linked to atmospheric pressure on the surface. I'd imagine a thicker atmosphere would help somewhat. Atmospheres also store a lot of heat, aside from greenhouse heating. Edited by T.Neo, Jan 27 2010, 03:34 PM.
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| A hard mathematical figure provides a sort of enlightenment to one's understanding of an idea that is never matched by mere guesswork. | |
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| Empyreon | Jan 27 2010, 03:44 PM Post #25 |
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Are you plausible?
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That's a good point. As you said, a thicker atmosphere would probably make dry land and air an option for life.
Did I miss where that connection was implied? |
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Take a look at my exobiology subforum of the planet Nereus! COM Contributions food for thought
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| Oceaniis | Jan 27 2010, 07:01 PM Post #26 |
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Adolescent
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Ok it would have very weak, but realy very weak magnetic field, it wouldn't protect the life, just a thick atmosphere would do it, and probably the planet have a thick atmosphere |
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| lamna | Jan 28 2010, 02:52 AM Post #27 |
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Sounds like a pretty barren planet, with extreme temperatures, little nutrients*, there is less light available, and if you get too close the the surface you'll get irradiated. There might be life, but it won't be common and probably not very complex. *Though comets and asteroids could provide a steady trickle. |
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Living Fossils Fósseis Vibos: Reserva Natural 34 MYH, 4 tonne dinosaur. [flash=500,450] Video Magic! [/flash] | |
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| Oceaniis | Jan 28 2010, 04:59 AM Post #28 |
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Adolescent
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It would have convection cells due the heat relezed by the planet cooling, if our ocean circulation due the sinking cold water in poles take oxygen to the deepths, would be no nutrients problems... The problem in my opinion is the low light for fotossintesis, no dout that "plants" will be black in color... Radiation isn't a problem.. flying animals would fly during night and stay underwater during day, or in the "hours" arround the midday |
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| lamna | Jan 28 2010, 07:32 AM Post #29 |
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How, you said that it would have so much water it would turn to ice before you hit the seabed. All you are going to churn up is ice. |
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Living Fossils Fósseis Vibos: Reserva Natural 34 MYH, 4 tonne dinosaur. [flash=500,450] Video Magic! [/flash] | |
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| T.Neo | Jan 28 2010, 10:08 AM Post #30 |
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Translunar injection: TLI
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Radiation shouldn't be a problem at all. Remember that Earth has lost it's magnetic field several times in history, with negligble effect on life. The atmosphere can shield us, and the atmosphere on Gliese 581d should be even thicker. The ocean would probably be convecting, if slowly. Most nutrient influx would probably come from volcanic activity: Gliese 581d is speculated to be highly volcanically active. The ice itself may actually be convecting as well, if extremely slowly. Glaciers and landforms on Mars, the moons of Jupiter and other outer planet moons show this. The atmosphere is also somewhat of a heat-sink, so I'd imagine it would both take time to cool down and time to warm up- temperatures might not be THAT extreme. And if there is indeed surface pack ice, what rules out, say, flying creatures roosting on the ice? |
| A hard mathematical figure provides a sort of enlightenment to one's understanding of an idea that is never matched by mere guesswork. | |
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