New study on tidal heating strengthens stellar habitability argument

Circumstellar Habitable Zone

Note: If you need a refresher on the habitability argument, click here.

Here’s an article entitled “Tidal heating shrinks the ‘goldilocks zone’: Overlooked factor suggests fewer habitable planets than thought”. It appeared in Nature, the most prestigious peer-reviewed science journal.

The gist of it is that tidal forces can alter orbits so that planets don’t spend all of their orbit in the habitable zone. If planets go outside the habitable zone, it damages their supply of liquid water, and any life chemistry going on in there is disrupted.

Excerpt:

A previously little-considered heating effect could shrink estimates of the habitable zone of the Milky Way’s most numerous class of stars — ‘M’ or red dwarfs — by up to one half, says Rory Barnes, an astrobiologist at the University of Washington in Seattle. That factor — gravitational heating via tides — suggests a menagerie of previously undreamt-of planets, on which tidal heating is a major source of internal heat. Barnes presented the work yesterday at a meeting of the American Astronomical Society’s Division on Dynamical Astronomy in Timberline Lodge, Oregon.

The habitable zone is the orbital region close enough to a star for a planet to have liquid water, but not so close that all of the water evaporates. For our Sun, the zone extends roughly from the inner edge of the orbit of Mars to the outer edge of that of Venus. For smaller, cooler stars, such as M-class dwarfs, the zone can be considerably closer to the star than Mercury is to the Sun. And because close-in planets are easier to spot than more distant ones, such stars have been a major target for planet hunters seeking Earth-like worlds.

There’s just one problem with finding habitable planets around such stars, says Barnes. Because tidal forces vary dramatically with the distance between a planet and its star, closer orbits also result in massively larger tidal forces.

Since planets do not have perfectly circular orbits, these tidal forces cause the planet to flex and unflex each time it moves closer to or further from its star; kneading its interior to produce massive quantities of frictional heat. Substantial heat can be produced, he added, with even slight deviations from a perfectly circular orbit. And, Barnes notes, other factors — such as the rate of the planet’s rotation and its axial tilt — can also influence heat production.

A similar tidal process makes Jupiter’s moon Io the most volcanic body in the Solar System. “I’m just scaling that Io–Jupiter system up by a factor of 1,000 in mass,” Barnes said at the meeting. “It’s the same process, on steroids.”

So, stars that are smaller and cooler will have a habitable zone that is closer to the star, exposing them to more tidal forces. More tidal forces makes their orbits less likely to stay circular – within the habitable zone around the star. These variations cause an increase in heat production on the planet. Too much heat means that the planet is unable to support liquid water on the surface, making it inhospitable for life. Therefore, solar systems with less massive stars can be ruled out as possible sites for life, because of these tidal forces.

Filed under: News, Agnosticism, Aliens, Astrobiology, Astronomy, Astrophysics, Atheism, Atheist, Belief, Carbon-based Life, CHZ, Circumstellar Habitable Zone, Complex Life, Earth, Exoplanet, Faith, Flying Spaghetti Monster, Freethought, Galactic Habitable Zone, Galaxy, GHZ, God, Guillermo Gonzalez, Hugh Ross, Life, Non-Theism, Planet, Privileged Planet, Reasons to Believe, Research, Science, Solar System, The Privileged Planet

Scientists discover that tides affect a planet’s habitability

Circumstellar Habitable Zone

Science Daily reports on a new factor that affects planetary habitability: tides. Specifically, tides can affect the surface temperature of a planet, which has to be within a certain range in order to support liquid water – a requirement for life of any conceivable kind.

Excerpt:

Tides can render the so-called “habitable zone” around low-mass stars uninhabitable. This is the main result of a recently published study by a team of astronomers led by René Heller of the Astrophysical Institute Potsdam.

[...]Until now, the two main drivers thought to determine a planet’s temperature were the distance to the central star and the composition of the planet’s atmosphere. By studying the tides caused by low-mass stars on their potential earth-like companions, Heller and his colleagues have concluded that tidal effects modify the traditional concept of the habitable zone.

Heller deduced this from three different effects. Firstly, tides can cause the axis of a planet`s rotation to become perpendicular to its orbit in just a few million years. In comparison, Earth’s axis of rotation is inclined by 23.5 degrees — an effect which causes our seasons. Owing to this effect, there would be no seasonal variation on such Earth-like planets in the habitable zone of low-mass stars. These planets would have huge temperature differences between their poles, which would be in perpetual deep freeze, and their hot equators which in the long run would evaporate any atmosphere. This temperature difference would cause extreme winds and storms.

The second effect of these tides would be to heat up the exoplanet, similar to the tidal heating of Io, a moon of Jupiter that shows global vulcanism.

Finally, tides can cause the rotational period of the planet (the planet’s “day”) to synchronize with the orbital period (the planet’s “year”). This situation is identical to the Earth-moon setup: the moon only shows Earth one face, the other side being known as “the dark side of the moon.” As a result one half of the exoplanet receives extreme radiation from the star while the other half freezes in eternal darkness.

The habitable zone around low-mass stars is therefore not very comfortable — it may even be uninhabitable.

Here is my previous post on the factors needed for a habitable planet. Now we just have one more. I actually find this article sort of odd, because my understanding of stars was that only high-mass stars could support life at all. This is because if the mass of the planet was too low, the habitable zone wouldbe very close to the star. Being too close to the star causes tidal locking, which means that the planet doesn’t spin on its axis at all, and the same side faces the star. This is a life killer.

This astrophysicist who teaches at the University of Wisconsin explains it better than me.

Excerpt:

Higher-mass stars tend to be larger and luminous than their lower-mass counterparts. Therefore, their habitable zones are situated further out. In addition, however, their HZs are much broader. As an illustration,

• a 0.2 solar-mass star’s HZ extends from 0.1 to 0.2 AU
• a 1.0 solar-mass star’s HZ extends from 1 to 2 AU
• a 40 solar-mass star’s HZ extends from 350 to 600 AU

On these grounds, it would seem that high-mass starts are the best candidates for finding planets within a habitable zone. However, these stars emit most of their radiation in the far ultraviolet (FUV), which can be highly damaging to life, and also contributes to photodissociation and the loss of water. Furthermore, the lifetimes of these stars is so short (around 10 million years) that there is not enough time for life to begin.

Very low mass stars have the longest lifetimes of all, but their HZs are very close in and very narrow. Therefore, the chances of a planet being formed within the HZ are small. Additionally, even if a planet did form within the HZ, it would become tidally locked, so that the same hemisphere always faced the star. Even though liquid water might exist on such a planet, the climactic conditions would probably be too severe to permit life.

In between the high- and low-mass stars lie those like our own Sun, which make up about 15% percent of the stars in the galaxy. These have reasonably-broad HZs, do not suffer from FUV irradiation, and have lifetimes of the order of 10 billion years. Therefore, they are the best candidates for harbouring planets where life might be able to begin.

This guy is just someone I found through a web search. He has a support-the-unions-sticker on his web page, so he’s a liberal crackpot. But he makes my point, anyway, so that’s good enough for me.

Maybe the new discovery is talking about this, but I already knew about it because I watched The Privileged Planet DVD. Actually that whole video is online, and the clip that talks about the habitable zone and water is linked in this blog post I wrote before.

Atheism hates science

• Physicist Frank Tipler weighs in on Stephen Hawking’s theory
• Peter Atkins claiming that nothing exists, (the physical universe is actually nothing)
• Stephen Meyer debating Michael Shermer on the origin of life
• Richard Dawkins explains why he won’t debate William Lane Craig
• How good are the arguments in the new book by Richard Dawkins?
• Richard Dawkins cites fraudulent research, runs from public debate
• Richard Dawkins thinks that aliens may have caused the origin of life
• Richard Dawkins cites German professor as authority on historical Jesus
• Analyzing Christopher Hitchens’ case against God

Theism loves science

• The origin of the universe from nothing
• The fine-tuning of the cosmological constants to permit life
• The fine-tuning of the galaxy, solar system, and planet to permit life
• Origin of the building blocks in the simplest replicating cell
• Origin of biological information in the simplest replicating cell
• Sudden origins of all major body plans in the Cambrian explosion
• Irreducible complexity in molecular machines
• The limits on what natural selection and random mutation can do
• Peer-reviewed paper says there is no atheistic explanation for the Cambrian explosion
• Does the Cambrian explosion disprove Darwinian evolution?

Filed under: News, Astrobiology, Astronomy, Astrophysics, Carbon-based Life, CHZ, Circumstellar Habitable Zone, Complex Life, Earth, Exoplanet, Faith, God, Life, Planet, Privileged Planet, Research, Science, Solar System, The Privileged Planet

Brian Auten interviews Jay Richards about Christian apologetics

Dr. Jay Richards

Christian scholar Jay Richards was interviewed by Brian Auten of Apologetics 315.

The MP3 file is here.

Topics:

• What is intelligent design (ID)?
• Is ID specifically Christian?
• How does ID helpful to Christian apologetics?
• What does ID prove?
• Is it OK to use an argument that doesn’t prove Christianity specifically?
• What is the difference between deism and theism?
• Do ID arguments get you to deism or theism?
• What is materialism, and how can you challenge it?
• How do opponents of ID define ID?
• What factors do you need to make a habitable planet?
• Are habitable planets common or rare in the universe?
• What is “The Privileged Planet” hypothesis?
• Is there an overlap between habitability and suitability for making scientific discoveries?
• What is the “Copernican Principle”?
• Has the progress of science made Earth seem common and ordinary?
• What is the most Earth-like planet that we’ve ever discovered?
• How should ID proponents respond to the objection that creatures aren’t perfect?
• Does having a big moon make a planet more or less habitable?
• Does a planet’s distance to the Sun make that planet more or less habitable?
• How do these two habitability factors affect the observability of solar eclipses?
• What does co-relation between habitability and “discoverability” tell us about God?
• How important is training in philosophy to Christian apologetics?
• What one thing should a Christian apologist work on to be more effective?

I’m hoping that Brian will do a follow-up interview with Jay on Jay’s new book on theistic evolution.

Here’s the description from Amazon.com:

What does it mean to say that God “used evolution” to create the world? Is Darwin’s theory of evolution compatible with belief in God? And even if Darwin’s theory could be reconciled with religious belief, do we need to do so? Is the theory well established scientifically? Is it true?

In the century and a half since Charles Darwin first proposed his theory of evolution, Christians, Jews, and other religious believers have grappled with how to make sense of it. Most have understood that Darwin’s theory has profound theological implications, but their responses have varied dramatically.

Some religious believers have rejected it outright; others, often called “theistic evolutionists,” have sought to reconcile Darwin’s theory with their religious beliefs, but often at the cost of clarity, orthodoxy, or both. Too few have carefully teased out the various scientific, philosophical, and theological claims at stake, and separated the chaff from the wheat. As a result, the whole subject of God and evolution has been an enigma wrapped in a shroud of fuzz and surrounded by blanket of fog.

The purpose of this anthology of essays is to clear away the fog, the fuzz, and the enigma. Contributing authors to the volume include Jay Richards, co-author of The Privileged Planet: How Our Place in the Cosmos Is Designed for Discovery; Stephen Meyer, author of Signature in the Cell: DNA and the Evidence for Intelligent Design; William Dembski, author of The Design Revolution; Jonathan Witt, co-author of A Meaningful World: How the Arts and Sciences Reveal the Genius of Nature; Denyse O’Leary, author of By Design, or by Chance?; and David Klinghoffer, author of Shattered Tablets.

Those authors are some of my favorite people to read in the whole world. I think this group will be mostly fed up with theistic evolutionists, like I am, although they may not go as far as I do when I label theistic evolutionists “functional atheists” or “theistic atheists”.

Jay Richards is probably my favorite all-round Christian scholar, because he also writes a lot on policy and economics, and was interviewed on those topics by Frank Turek. He has a complete, well-rounded worldview.

Posts featuring Jay Richards

• Jay Richards explains when you should doubt “scientific consensus”
• Fiscal and social conservatives unite in new free e-book “Indivisible”
• First Things reviews Jay Richards’ Money, Greed and God
• Video of the Stanford debate between Jay Richards and Christopher Hitchens
• Cato Institute talks with Jay Richards about Christianity and capitalism

Interviews by Jay Richards

• Ann Gauger’s new peer-reviewed paper on Darwinian evolution
• Doug Axe publishes a new peer-reviewed paper on protein folding

Related posts

• The origin of the universe from nothing
• The fine-tuning of the cosmological constants to permit life
• The fine-tuning of the galaxy, solar system, and planet to permit life
• Origin of the building blocks in the simplest replicating cell
• Origin of biological information in the simplest replicating cell
• Sudden origins of all major body plans in the Cambrian explosion
• Irreducible complexity in molecular machines
• The limits on what natural selection and random mutation can do
• Peer-reviewed paper says there is no atheistic explanation for the Cambrian explosion
• Does the Cambrian explosion disprove Darwinian evolution?

Filed under: Podcasts, Alien, Aliens, Analytical Philosophy, Apologetics, Axis, Christian Apologetics, Christianity, Copernican Principle, Deism, Discoverability, Earth, Earth-like Planet, Eclipse, Exoplanet, Fine Tuning, Galaxy, Guillermo Gonzalez, Habitability, History of Science, Intelligent Design, Jay Richards, Mars, Moon, NASA, Philosophy of Science, Planet, SETI, Solar System, Sun, The Privileged Planet, Theism

Harvard astrophysicist backs the Rare Earth hypothesis

What is the Rare Earth hypothesis?

It’s the thesis of a recent book written by two scientists at the University of Washington.

Here’s the blurb:

What determines whether complex life will arise on a planet? How frequent is life in the Universe?

In this exciting new book, distinguished paleontologist Peter D. Ward and noted astronomer Donald Brownlee team up to give us a fascinating synthesis of what’s now known about the rise of life on Earth and how it sheds light on possibilities for organic life forms elsewhere in the Universe.

Life, Ward and Brownlee assert, is paradoxically both very common and almost nowhere. The conditions that foster the beginnings of life in our galaxy are plentiful. But contrary to the usual assumption that if alien life exists, it’s bound to be intelligent, the authors contend that the kind of complex life we find on Earth is unlikely to exist anywhere else; indeed it is probably unique to our planet.

With broad expertise and wonderful descriptive imagery, the authors give us a compelling argument, a splendid introduction to the emerging field of astrobiology, and a lively discussion of the remarkable findings that are being generated by new research. We learn not only about the extraordinary creatures living in conditions once though inimical to life and the latest evidence of early life on Earth, but also about the discoveries of extrasolar planets, the parts Jupiter and the Moon have played in our survival, and even the crucial role of continental drift in our existence.

Insightful, well-written, and at the cutting edge of modern scientific investigation, Rare Earth should interest anyone who wants to know about life elsewhere and gain a fresh perspective on life at home which, if the authors are right, is even more precious than we may ever have imagined.

And here’s a review by Library Journal:

“Renowned paleontologist Ward (Univ. of Washington), who has authored numerous books and articles, and Brownlee, a noted astronomer who has also researched extraterrestrial materials, combine their interests, research, and collaborative thoughts to present a startling new hypothesis: bacterial life forms may be in many galaxies, but complex life forms, like those that have evolved on Earth, are rare in the universe. Ward and Brownlee attribute Earth’s evolutionary achievements to the following critical factors: our optimal distance from the sun, the positive effects of the moon’s gravity on our climate, plate tectonics and continental drift, the right types of metals and elements, ample liquid water, maintainance of the correct amount of internal heat to keep surface temperatures within a habitable range, and a gaseous planet the size of Jupiter to shield Earth from catastrophic meteoric bombardment. Arguing that complex life is a rare event in the universe, this compelling book magnifies the significance — and tragedy — of species extinction. Highly recommended for all public and academic libraries.”

Note that Peter Ward is a militant atheist (he has debated against Stephen C. Meyer), and Donald Brownlee is an agnostic. These are not Christians, nor are they even theists. However, I have the book, I have read the book, and I recommend the book. I usually have this book on my shelf at work for show-and-tell.

Now for the latest news about the hypothesis of the book. (H/T Brian Auten of Apologetics 315)

There are always going to be optimistic predictions by scientists who need to attract research funding, but those are hopes and speculations. The data we have today says Earth is rare. The number of conditions required for complex life of any kind is too high for us to be optimistic about alien life in this galaxy, at least. And as the number of requirements for life roll in, the odds of finding alien life that can contact us get slimmer and slimmer.

From the UK Daily Mail. (H/T Peter S. Williams)

Excerpt:

Dr Howard Smith, a senior astrophysicist at Harvard University, believes there is very little hope of discovering aliens and, even if we did, it would be almost impossible to make contact.

So far astronomers have discovered a total of 500 planets in distant solar systems – known as extrasolar systems – although they believe billions of others exist.

But Dr Smith points out that many of these planets are either too close to their sun or too far away, meaning their surface temperatures are so extreme they could not support life.

Others have unusual orbits which cause vast temperature variations making it impossible for water to exist as a liquid – an essential element for life.

Dr Smith said: ‘We have found that most other planets and solar systems are wildly different from our own.

‘They are very hostile to life as we know it.’

‘The new information we are getting suggests we could effectively be alone in the universe.

‘There are very few solar systems or planets like ours. It means it is highly unlikely there are any planets with intelligent life close enough for us to make contact.’ But his controversial suggestions contradict other leading scientists – who have claimed aliens almost certainly exist.

These arguments are actually quite useful, and I include them in my standard list of scientific arguments for theism. (See below) You have to know this stuff cold. Most people believe in aliens because they watched movies made by artists. As a result, they think that humans are nothing special and that God is not interested in us in particular. Which is very convenient for them, because it means they can do whatever they want and not care what God thinks about what they are doing. If you want to defend against the idea that humans are nothing special, and that we were not placed here for a purpose, and that we are not accountable and obligated to seek and know the Creator/Designer, then you’ll need more than feelings. You’ll need science. You’ll need the best science available.

Related posts

• The origin of the universe from nothing
• The fine-tuning of the cosmological constants to permit life
• The fine-tuning of the galaxy, solar system, and planet to permit life
• Origin of the building blocks in the simplest replicating cell
• Origin of biological information in the simplest replicating cell
• Sudden origins of all major body plans in the Cambrian explosion
• Irreducible complexity in molecular machines
• The limits on what natural selection and random mutation can do
• Peer-reviewed paper says there is no atheistic explanation for the Cambrian explosion
• Does the Cambrian explosion disprove Darwinian evolution?

Filed under: News, Alien, Alien Life, Aliens, Astrobiology, Astrophysics, Atmosphere, Calculation, Cambrian Explosion, Carbon-based Life, Carl Sagan, Circumstellar Habitable Zone, Complex Life, Cosmos, Crust, Donald Brownlee, Drake Equation, Earth, Extra-Terrestrial Life, Extremophile, Frank Drake, Galactic Habitable Zone, Galaxy, Guillermo Gonzalez, Habitability, Habitable, Habitable Zone, Humans, Intelligent Design, Jupiter, Life, Liquid Water, Microbial Life, Milky Way, Moon, NASA, Odds, Origin of Life, Peter Ward, Planet, Plate Tectonics, Probabilities, Probability, Rare Earth, Science, SETI, Space, Star, Sun, Sweeper, The Privileged Planet, Universe, Water

What are galactic habitable zones and circumstellar habitable zones?

You need to have a certain amount of elemental diversity to support the minimal requirements of living systems. For example, you need carbon, hence “carbon-based life”.

The Circumstellar Habitable Zone (CHZ)

Human bodies are made of carbon, and many other heavy elements. You need many different heavy elements in order to make up your physical body. Our star, the Sun, is also made of heavy elements. You also need heavy elements in order to crate a metal-rich star like our Sun. A heavy metal-rich star is required in order to support complex carbon-based life in any solar system. The metal-rich star is required because you need to make sure that it can burn stably for a LONG period of time.  A metal-rich star also allows you to have a habitable planet far enough from that metal-rich star so that the planet can support liquid water on the planet’s surface. The zone where a planet can have liquid water at the surface is called the circumstellar habitable zone (CHZ). A solar system is therefore a lot like a campfire – you can’t get too close or you get set on fire, and you can’t get too far or you freeze to death. With planets, you need to keep away so your water doesn’t evaporate from the surface, but not so far away that your water freezes. Liquid water on the surface is needed in order to act as a universal solvent in the chemistry of life.

 

Circumstellar Habitable Zone

 

Here, watch a clip from The Privileged Planet: (Clip 4 of 12, full playlist here)

A metal-rich star like the Sun is very massive, which allows planets to stay in orbit much further away. Notice that the smaller the star, the closer you have to go to the star. If you go too close to the star then your planet is “tidally locked” – your planet no longer spins on it’s axis – and that’s very bad for life)

The Galactic Habitable Zone (GHZ)

So, where do you get the heavy elements you need for your heavy metal-rich star?

You have to get the heavy elements for your star from supernova explosions – explosions that occur when certain stars die. That’s where heavy elements come from. But you can’t be TOO CLOSE to the dying stars, because you will get hit by nasty radiation and explosions. So to get the heavy elements, your solar system needs to be in the galactic habitable zone (GHZ) – the zone where you can pickup the heavy elements you need but not get hit by radiation and explosions. The GHZ lies between the spiral arms of a spiral galaxy. You can be too close to the center of the galaxy, it’s too dense there and you will get hit with massive radiation that will break down your life chemistry. And you can’t be to far from the center, because you won’t get enough heavy elements from the lower number of dying stars in the spiral arms.

 

Galactic Habitable Zone

 

Here, watch a clip from The Privileged Planet: (Clip 10 of 12, full playlist here)

The GHZ is based on a discovery made by astronomer Guillermo Gonzalez, which made the front cover of Scientific American in 2001. That’s right, the cover of Scientific American. That’s when this was discovered.

By the way, you can watch a lecture with Guillermo Gonzalez explaining his ideas further. The lecture was delivered at UC Davis in 2007. That link has a link to the playlist of the lecture, a bio of the speaker, and a summary of all the topics he discussed in the lecture. An excellent place to learn the requirements for a suitable habitat for life. The GHZ and CHZ are ONLY TWO of the requirements for a habitat for life – there are a lot more requirements! Once you list them all out, the odds of getting even one place that is suitable are quite low. If you like this sort of evidence, I recommend the DVD of “The Privileged Planet”, which you can get on Amazon. Or just watch it for free on YouTube.

Atheism hates science

• Physicist Frank Tipler weighs in on Stephen Hawking’s theory
• Peter Atkins claiming that nothing exists, (the physical universe is actually nothing)
• Stephen Meyer debating Michael Shermer on the origin of life
• Richard Dawkins explains why he won’t debate William Lane Craig
• How good are the arguments in the new book by Richard Dawkins?
• Richard Dawkins cites fraudulent research, runs from public debate
• Richard Dawkins thinks that aliens may have caused the origin of life
• Richard Dawkins cites German professor as authority on historical Jesus
• Analyzing Christopher Hitchens’ case against God

Theism loves science

• The origin of the universe from nothing
• The fine-tuning of the cosmological constants to permit life
• The fine-tuning of the galaxy, solar system, and planet to permit life
• Origin of the building blocks in the simplest replicating cell
• Origin of biological information in the simplest replicating cell
• Sudden origins of all major body plans in the Cambrian explosion
• Irreducible complexity in molecular machines
• The limits on what natural selection and random mutation can do
• Peer-reviewed paper says there is no atheistic explanation for the Cambrian explosion
• Does the Cambrian explosion disprove Darwinian evolution?

Filed under: Commentary, Agnosticism, Aliens, Astrobiology, Astronomy, Astrophysics, Atheism, Atheist, Belief, Carbon-based Life, CHZ, Circumstellar Habitable Zone, Complex Life, Earth, Exoplanet, Faith, Flying Spaghetti Monster, Freethought, Galactic Habitable Zone, Galaxy, GHZ, God, Guillermo Gonzalez, Hugh Ross, Life, Non-Theism, Planet, Privileged Planet, Reasons to Believe, Research, Science, Solar System, The Privileged Planet