Ice Water Worlds

I am getting caught up with my Astronomy magazine reading and was reading the article "Saturn's small wonders" in the March 2018 issue in which Francis Reddy discusses how "the Saturn system is also home to some of our solar system's most intriguing moons."

For example, Atlas and Pan both have equatorial ridges formed from the accretion of ring material, making them appear, as Reddy describes,  like ravioli. In an ice moon in a ring system of a gas giant, an ice moon large enough to have oceans under the ice, this accretion could form an equatorial mountain range which, because of gravity, would press down on the equatorial ice (though the spinning moon would counteract some of that) forming an ice ceiling mountain range.

Another thought involves air pockets under the ice. Moons orbiting large planets tend to be "massaged" by gravitational forces, especially if the orbits of the moons are not perfectly circular. This keeps adding energy to the moons, heating their core, creating dynamic worlds: undersea volcanism. This helps mix chemicals, increasing the chances of life forming (indeed, undersea vents on Earth are teeming with life and many feel that life may have gotten its start around such vents) as well as producing air bubbles.

So imagine sentient life evolving in such an ice-covered water world. The sky is a thick barrier of ice that has upside down ice mountains and valleys with air. For such life, this would be normal. A mostly dark world, lit up by the occasional volcano (most would be volcanic vents issuing gas but no bright lava), and, quite possibly, life forms that are bioluminescent; a mostly dark world that has a seabed with mountains and an ice roof with ice mountains. The whole universe is contained between the two. At the top of the universe are scattered air pockets and the sky cracks, with water flowing up to who knows where until the crack closes or freezes shut.

The sentient creature wonders: "What is beyond the ice roof? Where does that water go? Is there another water universe beyond that ice roof--a shared ice roof with another universe? But then why does the water only flow into that other universe and no water flows in? What comes in, comes in via the seabed vents...is there an ice base under the seabed? So are the worlds nested within each other?" Does their Jules Verne create a story of a journey to the center of their world only to break through and find another ice world?

Image: "Small Wonders." Cassini. NASA. 28 June 2017. "This montage of views from NASA's Cassini spacecraft shows three of Saturn's small ring moons: Atlas, Daphnis and Pan at the same scale for ease of comparison."

Planets With Four Suns May Be Not So Rare After All

While numerous two- and three-star systems containing planets have been discovered (with planet-harboring binary-star systems possibly outnumbering planet-harboring single star systems), four-star systems with planets were at first thought to be if not impossible, highly unlikely. How can a planet maintain an orbit? 

30 Ari a Double Double

However, we now know of two planet-harboring quadruple-star systems. First was Kepler-64b, found in 2012. The latest is a system called 30 Ari which lies 136 light-years away in the constellation Aries. The star system was first thought to be a triple-star system but a fourth star was discovered, making 30 Ari a double double-star system, with each binary orbiting a point in space between the two systems (the center of gravity for the entire quadruple-star system).

A diagram of the newfound system show the two pairs of stars in orbit together, while a planet circles one of them. Credit: NASA/JPL-Caltech

The Planet (30 Ari B b) 

The one planet found to date is a giant planet 10 times the mass of Jupiter and orbits the main star in 30 Ari  B every 335 days; it lies about 0.995 AU from the main star. The second star orbits at about 22 AUs away (for comparison, The Earth is 1 AU from the Sun, Uranus is around 20 AUs away, and Neptune is about 30AUs away). 

The planet orbiting the main star in 30 Ari B might lie just within the habitable zone. While the planet itself is probably not habitable due to its mass (it is most likely a gas giant), this does not rule out a habitable moon.

A Complicated Sky

A sentient being on such a hypothetical moon would see sometime in the daytime sky (when the gas giant is not occluding or blocking the main star) one small sun and two bright stars. With a large telescope, it would see that one of the bright stars was a binary system (30 Ari A binary system).

Some days, depending upon the tilt of the gas giant and thus the orbital plane of the moon with regards to the orbital plane of the stars, as well as possibly depending upon latitude if on a large moon, the sentient being would see just one (the main) star in the sky, or the main star with one of the two bright stars. One of those stars would show retrograde motion on a "yearly" basis.

Why celestial objects orbiting farther out display retrograde motion.
Credit: Prof. Pogge, Ohio State University.

Night, or when the gas giant is blocking the main 30 Ari B star, the sentient being would sometimes see those two bright stars (they would be the brightest nighttime stars), or just one of them, and sometimes none. If the moon is on the sun-facing side of the gas giant, the nighttime side of the moon would face the gas giant which would probably block any stars of any kind from being seen.

In fact, with a gas giant 10 times the mass of Jupiter, it is possible the moon beings would not see the night sky for part of their year. When their moon-planet is between the main star and the gas giant, night is just the gas giant. When the orbit begins to take the moon to the other side of the gas giant, then a starry night begins to be seen, with the day being replaced by a starry night (and the nights always the gas giant filling the sky, or filling most of it). This does depend upon how far away the moon is orbiting from the gas giant. Further away and then they may be able to see the night sky framing the gas giant, though most of the sky would still be the gas giant.

What a complicated sky! What complicated early religions would arise from such complexity? A mighty light in the sky that has two smaller, wandering lights that has a complicated dance.

If the newfound star is on the same orbital plane as the main 30 Ari B and main 30 Ari A stars, then sometimes the lesser lights (but still brighter than any other star) would seem to merge together, only to separate again, on a repetitive basis. If not, then they would approach and pass each other, with the newfound star being the fastest moving.

The 30 Ari A system would be like a zodiac indicator, for when the beings are able to see the night sky, since the 30 Ari A system is always opposite of the 30 Ari B system (circling a point in space in between the two systems). But since the 30 Ari A system is moving (both systems dancing around that shared point), that pointer would slowly move over the centuries, where, for example, the first day of spring used to be when 30 Ari A was in constellation D, it has slowly moved to where it is now in constellation E.

I would think that sentient beings would be pattern seekers on some level--visual ones would try to make some sense of the dots in the night sky, whether they would have a close equivalent to our concept of a zodiac is another matter. The stars will align at certain times of the year, times that are important for a primitive people to survive (best time to hunt, when to prepare for lean season, etc), as well as any religious meaning that gets attributed to stars and the movement/dance of those stars.

What kind of Stonehenge would arise in such a complex system? Though the aliens would be able to handle it--we had to figure out when eclipses would occur and that is no easy matter. 

Even More Complexity

Just as the two binaries orbit a shared center of gravity, the stars within each binary revolve around a shared center of gravity (or barycenter). The more alike in mass the two stars in a binary system are, the more the center of gravity will be outside of each star, in between. Two equally massive stars would orbit around a point essentially halfway between the two stars. A big imbalance in masses, however, could put the center of gravity inside the largest star. In our solar system the barycenter moves about as the planets have different masses, revolve at different rates, and are at different distances--sometimes the barycenter is inside the Sun, sometimes outside the Sun.

Solar System Barycenter Orbit Around Sun, from Wikimedia Commons. Credit Carl Smith, Rubik-Wuerfel.

Depending upon how heavy the newfound star turns out to be relative to the main star, the barycenter could be midpoint. Then the newfound star would never go behind 30 Ari B. The newfound star would sometimes be in the daytime sky and sometimes in the nighttime sky, but it would never be seen to merge with the main star. 30 Ari A still would--and depending upon orbital planes, could still look like it merges with the newfound star.

All Hail the Sky Giant

Retrogrades are hard to explain if you believe your planet is non-spinning. Would seeing a large gas giant spinning above you help a race to think of their planet, the gas-giant's moon, as spinning as well? With ancient humans, the Moon pretty much always kept the same face toward the Earth (we can see a wee bit more as the Moon's orbit is not perfectly circular). A gas giant, even if the giant's moon was tidally locked, would appear to be spinning. Even if the gas giant was tidally locked, there would be at least some cloud bands that would circle the globe and spin. However, maybe those cloud bands would be looked at as just clouds and no proof of a spinning planet.

On the other hand, the sentient beings would probably quickly realize they are orbiting that gas giant. The moon would not be the center of the universe--the gas giant would be. They may try to at first explain the night sky as everything circling the gas giant.

A gas giant that is always looking down on them, a huge presence every night. The main star is not as constant, disappearing behind the gas giant for part of each year. The two bright wandering stars also disappear behind (or into) the gas giant at different times of the year. A sense of pattern helps to put a mind at ease--chaos is dangerous, especially to early societies that are always on the edge of death due to climate patterns (from too little rain to too much rain to devastating storms or floods or fires during times of droughts, etc). And the one constant--the only constant (even if it face changes a bit with the cloud bands)--the gas giant, the sky giant.

Would the gas giant then be the home of the gods? Heaven? Hell? Birth place of the universe? A god itself?

The Great Eye(s)

And if that gas giant had one or more giant storms, like Jupiter, a big eye or eyes peering down? The ever watching eye...if tidal lock and always see the eye. If not, then the eye moves--watching the heavens, scanning creation, turning its eye upon the inhabitants of the moon on a regular basis.

When the eye appears, is that the time to supplicate to the great sky god? When its eye is most directed to the moon?

Asimov's Nightfall

Nightfall Begins

Magazine editor John W. Campbell asked Isaac Asimov to write a story based on a quote from Ralph Waldo Emerson, published in chapter 1 of Nature, Addresses and Lectures:

If the stars should appear one night in a thousand years, how would men believe and adore, and preserve for many generations the remembrance of the city of God!

Campbell thought that men would instead go mad.

Asimov set his story Nightfall on a planet (named Lagash) in a solar system containing six suns. Because of so many suns, Lagash normally does not experience a night--and no stars are seen. The people grow up thinking they are the center of the universe, that, in fact, their solar system IS the universe. But once very 2049 years, the suns align, eclipse, such that there is a brief night. And the population does go mad, destroying civilization, sending it back to the stone-age.

Under an Ever Blazing Sky

Creatures that evolve in such a system would probably have poor night vision. Though caves would still exist, and so dark places could be found. Though how scary those would be to creatures that have no night vision? Cloudy days would bring some dimness, but not darkness, not like night. And with multiple suns in the sky, even cloudy days would be, normally, brighter than a cloudy day on Earth.

What to make of all the suns in the sky--their complicated dance, how some drop down the horizon while others pop up, sometimes with this sun, sometimes with another; some suns move fast across the sky, others slowly. If two are binary, and revolve around each other, then how two of the suns seem to merge (if about the same apparent size) or embrace on a regular basis. And how the number of suns in the sky changes--sometimes with only one! What a complex mythology would most likely evolve.

And then the day that night arrives. It would most likely be a short night, but is it hard to imagine how a primitive race would panic as they look to leaders, religious leaders if they have them, to explain what was happening and there are no answers? Is this the end? As primitive humans banged on drums or shot arrows at the Moon during an eclipse, would, as in Asimov's story, people light as many fires as they can to chase away that unheard of darkness that blankets the planet?

Though would they see the stars? They do not have good night vision. If they saw the stars, would they think their suns were running away and now tiny? Or that the stars were tiny embers from a fire, the kind that float up in the air, from the fires of their suns that are now extinguished? Nightfall is a provocative story and one to read, or reread, if you are pondering what alien realities are out there in that immense expanse of space.

But could such a system be?

Scientists have discovered a planet in a four star system, 30 Ari. More on that later.

(Mostly) Water Worlds

Imagine a super Earth that is mostly covered in water. Landmasses are few and scattered. What would be the consequences for the development of an advanced civilization?

Landmass Size

For development of an advanced civilization on a super water world, I think it would have to be a water world where the landmasses are not miniscule. Tiny scattered islands would not give much evolutionary chances, or pressures, for life to leave the ocean (there would be but one ocean on a water world). What benefit would there be? There would not be enough territory for land creatures to have a go at it. There may be creatures that learn to live in the shallows, and there would probably be more shallow areas than areas above the ocean surface; and those creatures may venture at times on the land. Maybe some would evolve to use the land to lay eggs - protection from egg eaters. Some plant life that survive on the surface of the ocean could also end up being OK on the tiny islands - being small land masses, on a very large water world would mean waves, storms, rain, as well as a humid atmosphere (we suspect super Earths would have thick atmospheres, and may be steamy or humid). This atmosphere would potentially offer more protection from ultra violet radiation than our atmosphere, making it easier for surface water plants to survive periods on the land masses.

But for larger land masses - large enough to support evolution of land creatures - that is a different tale. Large land masses allow room for life to evolve permanent settlers, for a complex enough, and large enough, ecosystem to allow for permanent land adaptation. Once life evolves species to permanent adapt to land, they can then spread to smaller, relatively nearby, landmasses.

Landmass Separations

On a super Earth, even large land masses, close to Earth continents in size, would be separated by vast stretches of water - a vastness that would make our oceans seem like large lakes by comparison.

On Earth, landmasses separated for long periods show us divergent evolutionary paths. Each continent on a super Earth water world would have little biological communication with each other, at least for creatures that become fully established as land creatures. Semi-aquatic could eventually find their way to other landmasses, but those that evolve to be on land - each landmass would be a separate evolutionary laboratory.

An Aside

I have to stop for a moment here. While the evidence for evolution is overwhelming, it still has its holes, and thus it needs refining. But I also think that the Grand Designer of the universe has created the marvelous, awe inspiring, supremely elegant and beautiful natural laws that brought the universe to life. It's a sonnet, controlled by some regulations and restrictions, but allowing for so much expression within. For me, evolution is not anti-spiritual, but is evidence of a grand design, a remarkable design, that allows for such an incredible range of life in this universe. Many, many different songs of life, a Universe Symphony. And so, as science uncovers more truths of the universe, we will learn more of this Grand Design, and discover more of the beauty, the genius, the elegance of the Universe. This outlook informs my speculations. See "Introduction" for more on this blog's focus.

Evolutionary Laboratories

While the landmass lifeforms will have evolved from the same one ocean, the greatly separated major landmasses would allow for different evolutionary paths. Convergent evolution, where organisms not closely related (not monophyletic) independently evolve similar traits, would come into play, of course: lifeforms evolving similar adaptations because the occupy similar niches such as climbing trees, hunting at night, and eating burrowing insectoids. They would be on the same planet, within that planet's gravity well, magnetic field, and living through the planet's seasons as it orbits its star. But there will be variations in how each landmass' lifeforms specifically adapt. Natural disasters may affect one landmass while another is barely even touched by it - for instance, a supervolcano exploding on one landmass, but as the planet is a super Earth, and the landmasses greatly separated, the devastating effects of a supervolcano on this super Earth would not have the same global impact as a supervolcano explosion on Earth would. A meteor strike on a super water world would have less of a global impact, for the same size meteor, as that strike would on the Earth. A tsunami from an ocean strike would have much further to go, on a world with higher gravity, dissipating more of the tsunami's energy by the time it strikes a landmass than it would on the Earth. Not that there still would not be global effects from major disasters, it is just that with vast distances between at least some of the landmasses the effects for some areas of the planet would be much reduced. This would allow for very different end results. 

Dinosaurs Kingdoms and Mammal Kingdoms?   

If the Earth was a super water world, where it had, say, the same overall landmasses but with much, much greater distances between some of them due to the vastness of the global ocean, one result is that one continent would still have dinosaurs evolving, while another continent would have the dinosaurs wiped out, and the mammals evolving. Would this result in a sentient warm-blooded dinosaur race (probably feathered) on one continent, and sentient warm-blooded furry mammal race on another continent - intelligent descendants of the dinosaurs ruling one continent while intelligent humans ruling another? If the dinosaurs were not wiped out, could they have continued evolving, surviving the changing Earth to become sentient? Birds are the descendants of dinosaurs. Some birds, like crows, have brains twice the size needed for control of their bodies - they are much smarter than the other birds. Some even make tools (Caledonia crows can take a twig, strip it, and then work it until it has a hook at one end so that it can use it to hook insects burrowed in holes). If the dinosaurs were not wiped out by natural disaster(s) (some think more than one disaster ended their reign), could some have evolved to human level intelligence? 

What a world that would be. One day, an explorer from the dinosaur kingdom coming across the human kingdom, or vice versa.

Exploration

Which leads to my next speculation for this long post. For a world where continents are separated by distances many times what our continents are separated by, what would that mean for exploration? A sentient being is probably a curious one, and with a need to do some exploring, expanding territory. 

But as we see from our past, a large ocean is perilous to traverse. Many of our ancestors still did - we are finding that they traveled more, and farther, than we first thought. But it was perilous, and many resisted. For a continent that had only a few islands nearby and then nothing else, many early ships would leave to either never return or to return with no sightings of land. This would hold true for centuries as their sailing technology would not be enough to cover the incredible distances needed to get to another continent. The pressure to develop this technology would not be great - there is just no evidence for them, no tales of far off countries - just the known boundaries of their continent, the small islands off the coast, and that is it. The known world. The center of the world, and of the universe, as known to them. 

This separation, this loneliness, would allow the separated sentient beings on the separated continents to progress on their own, focusing on their known world, their center of the world. Until one day at least one progresses to the point where they can begin to think of exploring the universe. As knowledge increases, as they being to realize their world is a giant sphere, they may again wonder if some continent lies far, far away, just like we use to wonder if sentient life existed on Mars, or the Moon. Scientific exploration leads to technology that finally enables them to send a probe around the planet, or a long range probe to cross the seas (though a planet orbiting probe is the much more efficient means), and they spot it - another continent. 

Contact

And now the final speculations for this long post What myriad of ways that could play out? A civilization more advanced but for some reason didn't launch an orbiting probe (their culture focused more inward for whatever reasons - political,  theological, or distracted by a more harsh environment and needing to spend more energies there). Or a civilization less advanced. People similar in body form, but still different enough: humanoid but with tails, or humanoid but much smaller. Or more aggressive. Or not humanoid at all. The first contact hidden by the government of the country that sent the probe because of the differences - delaying actual contact. Or used by the government to rally their dissafected people against a perceived enemy?  Or this other land thought of as being heaven, or hell, or .... So very many different ways that first contact could play out.

Very Elliptical Orbits and Possible Life

As Spock Would Say?

From time to time I read about how planets in very elliptical orbits, orbits which take the planet in and out of the star's habitable zone, will probably not harbor life. Just too extreme. Of course if such a planet can support life, it would be, as that saying by Mr. Spock goes "it's life, Jim, but not as we know it." (Yes, I know that the line was not spoken by Spock in the series, but only in The Firms' song "Star Trekkin.'") But wait a minute. In pondering the report mentioned in the Creatures Frozen for 32,000 Years Still Alive post below maybe we should revisit those assumptions.

Or Not

Bacteria have been found buried deep in solid rock - bacteria with very slow metabolic states and are probably thousands of years old. Penn State scientists discovered in Kalaallit Nunaat (Greenland) dormant ultra-small bacteria (Chryseobacterium greenlandensis) trapped 2 miles deep in 120,000 year old ice core samples. If Earth creatures can reanimate after being frozen for tens of thousands of years, if other Earth creatures can last for hundreds of thousands of years, or even millions, then 1) life can be possible in very elliptical orbits and 2) it still could be life as we know it. We have many example of extreme life on Earth, living under conditions scientists not long ago said were not able to support life: from deep in antarctic ice, to miles below the surface of the Earth, to boiling hot springs, to volcanic vents on the sunless depths of the ocean floor, to acidic mine drainage, to the stratosphere -- life is everywhere on this planet, and in many, many forms.

Kol-Ut-Shan, as Spock Would More Likely Say

So, is it truly implausible that life can evolve on planets that orbit in and out of the habitable zone? Evolution may possibly take longer, but the most common star, the red dwarf, develop very slowly, lasting up to hundreds of billions of years. Plenty of time for life to evolve and in its own fashion thrive. Most of the time we put a limit on where life can exist on the Earth, we later find we are wrong.

Maybe we should embrace the Star Trek Vulcan philosophy of IDIC: Infinite Diversity from Infinite Combinations (Kol-Ut-Shan according to an episode of ST: Voyager). Though if life has universal laws (like physics and chemistry, on which biology depends), I am not sure about the Infinite part. Natural laws do have some limits, boundaries, ranges. But  even so, the range of diversity that can arise is still vast. Maybe it should have been ADAC: Astronomical Diversity from Astronomical Combinations. Or IDAC: Incredible Diversity from Astronomical Combinations. Of course, it is a trivial difference to be concerned over.
 
What matters is that there is an incredible array of life on this planet. Especially if we not only consider all the varied environments life can be found now on Earth, but all the varieties of life that have existed in all the varied Earth environments (some radically different) in the past as well. An incredible, astronomical diversity. 


Reference:

Coghlan, Andy. "'Resurrection Bug' Revived after 120,000 Years." Life. New Scientist. 15 June 2009. Web. 30 July 2009. <http://www.newscientist.com/article/dn17305-resurrection-bug-revived-after-120000-years.html>

Helmuth, Laura. "Top Ten Places Where Life Shouldn't Exist... But Does." Science & Nature. Smithsonian Magazine. 13 October 2009. Web. 5 September 2012. <http://www.smithsonianmag.com/science-nature/Top-Ten-Places-Where-Life-Shouldnt-Exist-But-Does.html#ixzz25e81Ip2i> 

"IDIC" Memory Alpha, The Star Trek Wiki. n.d. Web. 5 September 2012. <http://en.memory-alpha.org/wiki/IDIC>

"Novel bacterial species found trapped in Greenland's ice." Penn State Live. Penn State University. 3 June 2008. Web. 30 July 2009. <http://live.psu.edu/story/31052>

New Technique to Weigh Planets

New Technique to Weigh Planets

Summary: For the first time, scientists have developed a method for determining the mass of non-transiting exoplanets. The research could even lead to techniques for detecting molecules associated with the presence of life on such worlds.

All Known (as of June 2012) Planets to Scale (drawn by xkcd)

http://xkcd.com/1071/

http://www.planetary.org/blogs/mat-kaplan/20120620-xkcd-all_exoplanets.html