A Hypothetical Habitable Moon
(From Lucianomendez, via Wikimedia Commons, used w/o permission.)
("Artist's impression of a hypothetical habitable moon of Upsilon Andromedae d.")
That's a cool picture, but we don't know if Upsilon Andromedae d has moons: let alone one with an atmosphere, ocean, and clouds. Using a new exomoon detecting technique, we may soon know how closely the artist's impression matches reality.
If Upsilon Andromedae d has a terrestrial moon, that world's climate will make weather extremes here in Minnesota seem positively placid by comparison.
More About Upsilon Andromedae d Than You Need to Know
(From Sylvain Korzennik and the AFOE team, via NASA, used w/o permission.)
("A diagram of the orbits of the 3 planets around Upsilon Andromedae. The red dots mark the orbits of planets b,c and d. The dashed circles show the orbits of Mercury, Venus, Earth and Mars to give the scale of the orbits.")
Upsilon Andromedae d comes within about 1.88 AU (the distance from Earth to the sun) before heading out to a little over 3 AU from its sun.
Earth's orbit around our star is nearly circular, so our seasons happen because Earth's axis is tilted. Upsilon Andromedae d's winter would be when it's farther from its star: receiving less than half as much light and heat at apastron as it does when it's closest.
Upsilon Andromedae is hotter and about three and a half times brighter, than our star: and between 2,600,000,000 and 3,300,000,000 years old. That's younger than Sol's roughly 4,600,000,000 year age: so planets in the Solar system are at least 1,300,000,000 years older than Upsilon Andromedae's set.
If Upsilon Andromedae d has a habitable moon, and if life there developed at the same rate as life did on Earth, we'd find a world in its Proterozoic era, with some oxygen in the atmosphere and multicellular critters in the ocean: but no prospect of the critters like trilobites for another billion years or so.
As I've said before, that's a lot of "ifs."
Exploding Martians?
(From Roel van der Hoorn, using NASA images, via Wikimedia Commons, used w/o permission.)
(Viking 1 Lander on Mars.)
If there is life elsewhere in the universe, it may be on a planet very much like Earth: or not.
We've found critters living in hot springs, under glaciers, and inside rocks. Scientists are studying extremophiles, to learn where we can look for life: and what to look for.
Several years back, a scientist suggested that "peculiar chemistry" found by the Viking lander was what was left after Martian microbes exploded.
The University of Giessen's Joop Houtkooper pointed out that pouring water on critters designed to survive on Mars could easily kill them. (Apathetic Lemming of the North (March 5, 2009))
Life Not Quite as We Know It
On earth, plants use sunlight to split water into hydrogen and oxygen: bonding the hydrogen to other elements and storing it in their tissues; releasing the oxygen. Plants and animals use energy stored in the hydrogen compounds by combining the hydrogen with oxygen taken from the air or water.
That's vastly oversimplified, of course, but covers the basics of the water/hydrogen-oxygen cycle we call life. Part of it, anyway. A little over a half-century back, someone sketched out the basics of a plausible alternative to "life as we know it:"
"...Imagine a planet the size of Uranus in the position of Mars. It has just managed to hang on to enough hydrogen to allow it to be a major component of the atmosphere, along with ammonia, methane and carbon dioxide, and yet the planet is just warm enough to allow the presence of liquid water.In the same chapter, Asimov outlined other slightly-plausible life chemistries: including one where plants break sulfur dioxide into sulfur and oxygen, store the oxygen, and release liquid sulfur. Animals would eat the high-oxygen planets and drink sulfur, releasing sulfur dioxide.
"Plant life on such a world might split water to hydrogen and oxygen. It would then combine oxygen and methane (which it breathes) to form starch, liberating the hydrogen into the atmosphere. The methane would be replaced by hydrogen, the carbon dioxide would be reduced to methane and then replaced by hydrogen, the ammonia would stay put. The atmosphere of the world would end as only hydrogen and ammonia.
"Animals would eat the starch, breathe the hydrogen, recombine the oxygen of the starch with the hydrogen to form water, and breathe out methane gas.
"Our situation exactly, but in reverse...."
("Only a Trillion" Isaac Asimov, Ace Books (1957) (revised and updated 1976); pages 108-109)
At Earth's seal-level pressure, sulfur melts at about 115 °C (239 °F) and boils at 444 °C (832.3 °F) — so we couldn't live on a world with sulfur oceans. The element isn't as common in the universe, or on Earth, as oxygen: but it's not as rare as, say, iodine or silver.
A few years ago I ran into an intriguing bit of informed speculation: Earth may be about as small as a planet can be, and still support life: and that's another topic.
Exoplanets: Hot Jupiters, Super-Earths, and More
Scientists have cataloged 1786 planets orbiting other stars. These exoplanets are in 1106 planetary systems, including 460 multiple planetary systems. That was last Saturday. The tally may have gone up since then.From what we've found in our neighborhood, scientists estimate that there are between 160,000,000,000 and 400,000,000,000 planets in this galaxy.
One planet, PSR B1257+12 A, is only twice as massive as Earth's moon. Another, DENIS-P J082303.1-491201 b, is almost 29 times as massive as Jupiter.
We discovered planets unlike anything in the Solar system: including hot Jupiters and super-Earths. Super-Earths aren't necessarily habitable. It's a term for planets with more mass than Earth, but not enough to be a gas giant like Uranus or Jupiter.
A super-Earth might not have an atmosphere, or be shrouded in a hydrogen-helium mix like the Solar system's outer planets. On the other hand, a super-Earth might be chemically similar to Earth: complete with water, and — maybe — have air that's a cloudy mix of nitrogen and oxygen maintained by a lively ecosystem; just like Earth, only bigger.
One star, Gliese 581, has three super-Earths in or close to its habitable zone.
More, about the size of super-Earths:
- "The Mass-Radius Relation
for 65 Exoplanets Smaller Than 4 Earth Radii"
Lauren M. Weiss and Geoffrey W. Marcy, B-20 Hearst Field Annex, Astronomy Department, University of California, Berkeley, CA; ApJ Letters (January 30, 2013)
(From arxiv.org/abs/1312.0936 (May 15,2014))
1. Looking for New Moons
(From Astrobiology.net, used w/o permission)
"New Exomoon Hunting Technique Could Find Solar System-like Moons"We've been discovering that some planets resemble our neighbors in the Solar system: and many are like nothing we'd seen before.
Adam Hadhazy, Astrobiology Magazine (May 12, 2014)
"Summary: Looking for tiny, additional shadows built up during multiple mini-eclipses of stars could reveal the existence of exomoons.
"Among the most sought-after prizes in astronomy these days are 'exomoons,' or moons orbiting exoplanets. Although astronomers have detected more than a thousand exoplanets, any exomoons they might harbor have so far eluded capture. However, judging by our own Solar System, where moons greatly outnumber planets, scientists believe that hordes of exomoons are indeed out there.
"To find these exomoons hiding in plain view, a new technique has just been proposed. Described in a study recently accepted in The Astrophysical Journal, the new approach relies on a particular eclipsing effect of moons when viewed against the background radiance of their host stars...."
I will be very surprised if we don't learn that there's more to moons than the selection near home.
"Traditional Exomoon Hunting Techniques"
"Unlike traditional exomoon hunting techniques, the new method has the advantage of being able to find natural satellites on the scale of the moons here in the Solar System. Other methods can probably only yield exomoons several times the mass of the biggest moon known, Jupiter's Ganymede — in other words, unprecedentedly monstrous moons.My hat's off to Adam Hadhzay and Astrobiology Magazine, for not dragging in the dusty claim that Galileo was punished for being scientific.
" 'This technique is the first method that has been demonstrated to allow detection of moons akin to those in the Solar System,' said study author René Heller, a postdoctoral fellow in astronomy at McMaster University, in Ontario, Canada. 'Four hundred years after Galileo Galilei discovered four moons orbiting Jupiter, the first moons we knew of besides our moon, we now have the technologies and methods available to go find 'alien' moons beyond our Solar System.'..."
(Adam Hadhazy, Astrobiology Magazine)
The assumption that Christianity opposes science is cherished so fervently, or taken for granted so often, that I'm impressed when the Galileo-as-victim myth isn't trotted out.
Sure, some Christians desperately insist that a 17th-century Calvinist was right, but ignorance is not required for Catholics. (April 25, 2014; April 18, 2014)
Bottom line, God made what we can observe and the things of faith: so honest study of this vast and ancient universe cannot hurt faith. Truth cannot contradict truth. (Catechism of the Catholic Church, 159)
I've wondered if some 'religious' diffidence towards science is a response to how much we've been learning about this creation over the last few centuries. It's not easy to keep up.
In my youth, speculation about planets orbiting other stars was mostly a matter for science fiction writers. Today, we have "traditional exomoon hunting techniques."
I enjoy living in a rapidly-changing world: but not everyone does.
Using Kepler's Data
(From Rene Heller, via Astrobiology Magazine, used w/o permission.)
("This figure from Heller's paper shows how the shadows of exomoon transits overlap on each other more at the "wingtips" than the inner portion of an exomoon's orbital path around its host planet. This stacking effect means that the wingtip shadows are darker, a phenomenon that could be exploited to find exomoons.")
"...Additionally, the new method can distinguish multi-moon systems, whereas standard techniques focus on solo exomoons. A third benefit is that existing data from the Kepler spacecraft should suffice for identifying exomoons. That's in contrast to some other proposed methods which would require new technologies and force exomoon hunters to await future generations of telescopes.Applying improved analysis techniques to existing data can save time and expense: and, I think, may give scientists a better idea of what sort of equipment needs to be developed next.
"Intriguingly, the method could tease out the presence of exomoons orbiting planets in the so-called habitable zones of red dwarf stars and orange dwarfs. The habitable zone is the not-too-close, not-too-far-away band around a star wherein residing worlds could have liquid water...."
(Adam Hadhazy, Astrobiology Magazine)
Finding moons orbiting planets like the Solar system's Jupiter or Neptune would help scientists fine-tune explanations for how planets and moons form: or show that today's explanations don't work. Either way, we'd learn more about this universe.
Finding an Earth-size moon orbiting a Saturn-sized world in its star's habitable zone, though: that would be very exciting indeed.
(From NASA, via Astrobiology.net, used w/o permission.)
("An artist's impression of exomoons orbiting a gas giant in an alien solar system. In this vista, the nearest exomoon appears Earthlike, and thus potentially habitable.")
"Habitable:" In the Eye of the Beholder
(From Rene Heller, via Astrobiology.net, used w/o permission)
("A figure, also from Heller's paper, shows what the first half of an exoplanet-exomoon transit would look like, averaged over time. Heller's orbital sampling effect method looks for the two small dips in the amount of starlight blocked before and after the big dip caused by the exoplanet. In the second half of the transit, the signals reverse, with two small brightening events bracketing a big brightening event.")
"...To date, the most common planets found in habitable zones are not Earth-sized (though a substantial number of earthly twins could emerge from Kepler data yet to be analyzed). Rather, habitable zone-dwellers are often 'super-Earths' and gas giants. The latter certainly, and some have argued the former, cannot serve as abodes for life. But their moons could be a different story."Habitable" may be in the eye of the beholder.
" 'Super-Earths and giant planets have been observed to be much more abundant in the stellar habitable zones than truly Earth-sized planets,' said Heller. 'While super-Earths and giants may not be habitable, their moons might be. Hence, habitable moons may be much more common than habitable planets.'..."
(Adam Hadhazy, Astrobiology Magazine)
As I said in this post's introduction , 'habitable' planets might typically be cooler than Earth, with air that's a mix of hydrogen and ammonia, and surface gravity about three times what we consider comfortable.
If that's the case, there may be more 'habitable' exoplanets than we think: since super-Earths seem to be more common that Earth-size worlds. This might even help explain why we haven't had visits from space aliens: assuming that we aren't alone in the universe: and that's another topic.
2. Solar Sibling: Found
(From Ivan Ramirez/Tim Jones/McDonald Observatory, via FoxNews.com, used w/o permission.)
("The star HD 162826 is probably a 'solar sibling,' that is, a star born in the same star cluster as the sun. It was identified by University of Texas at Austin astronomer Ivan Ramirez, in the process of honing a technique to find more solar siblings in the future, and eventually to determine how and where in the Milky Way galaxy the sun formed.")
"Solar siblings? Astronomers discover sun's long-lost brother"I'm pretty sure that Ivan Ramirez didn't have the metaphysical question of existence in mind when he said that finding which part of the galaxy our star is from would "help us understand why we are here." His team has been studying the process of stellar formation: specifically how and where the Solar system began.
FoxNews.com (May 10, 2014)
"It turns out that the sun has a long-lost brother -- and now astronomers are racing to map a solar family tree.
"A new study from researchers at the University of Texas provides clues as to how our sun was formed, whether there are other 'solar siblings' in our universe and, perhaps, a better understanding of how life in the universe was formed billions of years ago.
"The finding, which will be published next month in The Astrophysical Journal, identifies a star that was almost certainly born from the same cloud of gas and dust as the sun. Located 110 light years away in the constellation Hercules, the star, called HD 162826, is 15 percent more massive than our sun, and can be seen with low-power binoculars.
" 'We want to know where we were born,' University of Texas at Austin astronomer Ivan Ramirez said in a news release from McDonald Observatory. 'If we can figure out in what part of the galaxy the sun formed, we can constrain conditions on the early solar system. That could help us understand why we are here.'..."
I'm looking forward to seeing what we learn about the early years of our home: but I don't expect that knowledge, fascinating as it is, to explain the significance or our existence.
I've been over this before: science, the systematic study of this creation, is okay; religion, the systematic study — and, sometimes, worship — of the spiritual side of reality is okay. Both can be, and have been, misused: sometimes very destructively. But both can be useful, in different ways:
- Science
- What things are
- How they work
- Religion
- Why things are
- How we should deal with them
Nebulae, Stars, and Time
(From ESA/Hubble, via Wikimedia Commons, used w/o permission.)
(Part of the Orion Nebula.)
Over the last century, scientists have speculated that the Solar system formed when:
- Two stars nearly collided
- Our sun tore a low-density companion star to shreds
- A rapidly-spinning early sun spat out planets, one at a time
- The sun and planets condensed from a nebula
- Something else happened
Since stellar formation takes place over thousands to millions of years, it'll be quite a while before we have the equivalent of a home movie for the birth of a single star.
3. Cosmic Crash, Crust, and Critters
(From Don Davis/NASA, via FoxNews.com, used w/o permission.)
("A large impactor slams into the Earth in this artist's impression.")
"How Cosmic Crashes Could Have Kickstarted Plate Tectonics"Plate tectonics is a theory that describes how Earth's crust forms along mid-ocean ridges and sinks along subduction zones. It's also the best explanation yet for why the edges of continental shelves fit together like pieces of a jigsaw puzzle.
Elizabeth Howell, Astrobiology Magazine (May 5, 2014)
"A rock the size of a small city hurtles towards Earth, smashing a crater bigger than the span between Washington, D.C. and New York City. The heat and shockwave raises the temperature of the atmosphere above boiling as huge seismic waves ripple through the Earth's crust.
"New research indicates that such an impact may have happened to our planet, although (thankfully) it was long before civilization arose. About 3.26 billion years ago, an object between 23 and 26 miles wide (37 and 58 kilometers) crashed into the Earth somewhere and left geological evidence behind in South Africa. Surprisingly, the impact may have made the Earth a friendlier place for life because it corresponds with this planet's establishment of plate tectonics...."
Earth is the only planet we know of with active plate tectonics. Since this is also the only planet that we know supports life: maybe there's a connection between our planet's shifting crust and the critters living here.
When Earth was New: Putting the Pieces Together
(From NOAA, via Astrobiology Magazine, used w/o permission.)
("Crustal plate boundaries showing plate tectonics on Earth.")
"...Finding the crater, though, is likely an impossible task. There are few rocks of this age on the entire Earth, the notable exception being the nearly 4-billion-old Canadian Shield that stretches across much of eastern Canada. Little remains of that era of history, making it necessary for researchers to do detective work to learn more about the impactor....The Late Heavy Bombardment, if it happened, ran from 4,100,000,000 to 3,800,000,000 years ago. The last I heard, the jury's still out on whether or not there really was an uptick in the frequency of large asteroid collisions in the inner Solar system.
"...Perhaps microbes would have suffered after the impact, but in its wake, the impactor could have helped change our planet into one that better supports complex life. Lowe pointed out that plate tectonics seems to have appeared around 3 billion to 3.2 billion years ago, around the same time the impactor smashed into the Earth.
"Huge as it was, the impactor was probably too small to have affected plate tectonics all over the Earth, said Lowe and Sleep. In the local area, however, it could have caused great upheaval. Moreover, the impactor crashed into the Earth during an era known as the Late Heavy Bombardment, when rocks and comets smashed into our planet and all the other ones. The Moon still bears scars from that time. The Earth's have eroded away, but the effects may still linger.
"If enough big objects hit the Earth frequently enough, it could have broken up the primitive plate structure on our planet into the plate tectonics we have today, they said. This has important implications for life, as other researchers have said that plate tectonics might be necessary for complex life to exist...."
(Elizabeth Howell, Astrobiology Magazine)
If the Late Heavy Bombardment is real, and not just a sampling error, the start of plate tectonics on Earth not long (by geological standards) after the LHB stopped is at least an odd coincidence.
I'm pretty sure that we'll find that it took more than multiple asteroid hits to start Earth's crust moving around. Venus and Mars, Earth's closest neighbors, presumably had about as many asteroid impacts as Earth: maybe more, for Mars, since that planet's closer to the asteroid belt.
But neither planet seems to have had Earth's shifting crust.
Venus isn't all that far from Earth: and although that planet has two small 'continents,' Ishtar Terra, and Aphrodite Terra, there doesn't seem to have been much in the way of a moving crust. Not in the last 300,000,000 years or so, anyway. Volcanoes, yes: moving plates, no.
Mars has volcanoes, including the famous Olympus Mons; but again, no evidence of moving crustal plates.
Since Earth is the only planet we know of where the crust gets recycled in subduction zones and new crust is created at mid-ocean ridges, many assume that plate tectonics is necessary for life.
On the other hand, maybe life is necessary for plate tectonics; or continents, at any rate:
- "Does a Planet Need Life to Create Continents?"
Charles Q. Choi, Astrobiology Magazine (January 6, 2014)
Related posts:
- Earth
- "Whale Fossils in a Desert, Ancient Zircons, and a Changing World"
(February 28, 2014)
Particularly - "Scorpions, Acid Rain, and the Great Dying"
(November 29, 2013)
Particularly - "Oxygen, Life, and Autocells"
(October 18, 2013) - "Oxygen, Ice, and Our Changing Earth"
(August 30, 2013)
- "Whale Fossils in a Desert, Ancient Zircons, and a Changing World"
- The universe
- "Habitable Worlds, Homer, and Haldane — or — Ganymede's Oceans, and Imagining Kepler-186f's Sunsets"
(May 9, 2014)
Particularly - "Fish, Extremophiles, and the Emperor's New Clothes"
(March 7, 2014)
Particularly - "Planets, Creation's Afterglow, and Double Stars"
(February 7, 2014)
Particularly - "Earth May Not Be a 'Class M' Planet"
Apathetic Lemming of the North (December 5, 2009) - "Diamonds: Ancient Crystals, New Speculation, and the Origin of Life"
Apathetic Lemming of the North (July 28, 2008)
- "Habitable Worlds, Homer, and Haldane — or — Ganymede's Oceans, and Imagining Kepler-186f's Sunsets"
- And beyond
- "Life in the Universe, God, and Getting a Grip"
(October 17, 2013) - "Science, Faith, and Albertus Magnus"
(February 23, 2014) - "Seeking Truth, Accepting Vastness"
(April 2, 2013) - "Science isn't a Four-Letter Word"
(January 29, 2012) - "Astrobiology, the Vatican, and the Meaning of Our Existence"
(November 12, 2009)
- "Life in the Universe, God, and Getting a Grip"
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