# Our sun is just a typical star?

A friend wants to know how to respond to this sort of claim, which surfaced for example in Astrophysical Journal (2008):

If the origin of life and the evolution of observers on a planet is favoured by atypical properties of a planet’s host star, we would expect our Sun to be atypical with respect to such properties. The Sun has been described by previous studies as both typical and atypical. In an effort to reduce this ambiguity and quantify how typical the Sun is, we identify eleven maximally-independent properties that have plausible correlations with habitability, and that have been observed by, or can be derived from, sufficiently large, currently available and representative stellar surveys. By comparing solar values for the eleven properties, to the resultant stellar distributions, we make the most comprehensive comparison of the Sun to other stars. The two most atypical properties of the Sun are its mass and orbit. The Sun is more massive than 95 -/+ 2% of nearby stars and its orbit around the Galaxy is less eccentric than 93 +/- 1% of FGK stars within 40 parsecs. Despite these apparently atypical properties, a chi^2 -analysis of the Sun’s values for eleven properties, taken together, yields a solar chi^2 = 8.39 +/- 0.96. If a star is chosen at random, the probability that it will have a lower value (be more typical) than the Sun, with respect to the eleven properties analysed here, is only 29 +/- 11%. *These values quantify, and are consistent with, the idea that the Sun is a typical star. If we have sampled all reasonable properties associated with habitability, our result suggests that there are no special requirements for a star to host a planet with life.

Well, some of us think Enrico Fermi had the right answer here: If there are “no special requirements for a star to host a planet with life” (= any old fireball will do), where are all those space aliens?

See also: The Science Fictions series at your fingertips (cosmology) for why people need to believe that Earth is not unusual, and the nonsense that is fronted in order to maintain the belief.

## 8 Replies to “Our sun is just a typical star?”

1. 1
bornagain77 says:

A few notes:

Overlooked factor suggests fewer habitable planets than thought – Richard A. Lovett – 08 May 2012
Excerpt: There’s just one problem with finding habitable planets around such stars (red dwarfs), 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.,,, 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.”
http://www.nature.com/news/tid.....ne-1.10601

Red dwarf
Excerpt: A red dwarf is a small and relatively cool star on the main sequence, either late K or M spectral type. They have a mass of less than half that of the Sun (down to about 0.075 solar masses, below which stellar objects are brown dwarfs) and a surface temperature of less than 4,000 K. Red dwarfs are by far the most common type of star in the Galaxy, at least in the neighborhood of the Sun,,
http://en.wikipedia.org/wiki/Red_dwarf

A Renewed Concern: Flares and Astrobiology – January 2011
Excerpt: “Such powerful flares bode ill for any possible biology, life, on any planet that happens to be close to that flaring star. It’s extraordinary to think that the most numerous stars, the smallest ones in our galaxy, pose this threat to life.”
http://www.centauri-dreams.org/?p=16327

Star Chemistry Constrains Habitable Zone (additional constraint to the Privileged Planet Principle) Sept. 2012
Excerpt: If there had been less oxygen in the Sun’s chemical makeup, for example, Earth likely would have been pushed out of the Sun’s habitable zone about a billion years ago, well before complex organisms,,,
http://crev.info/2012/09/star-.....able-zone/

etc.. etc..

Fine Tuning Of Universal Constants, Particularly Light – Walter Bradley – video
http://www.metacafe.com/watch/4491552

Fine Tuning Of Light to the Atmosphere, to Biological Life, and to Water – graphs

Visible light is also incredibly fine-tuned for life to exist. Though visible light is only a tiny fraction of the total electromagnetic spectrum coming from the sun, it happens to be the “most permitted” portion of the sun’s spectrum allowed to filter through the our atmosphere. All the other bands of electromagnetic radiation, directly surrounding visible light, happen to be harmful to organic molecules, and are almost completely absorbed by the atmosphere. The tiny amount of harmful UV radiation, which is not visible light, allowed to filter through the atmosphere is needed to keep various populations of single cell bacteria from over-populating the world (Ross; reasons.org). The size of light’s wavelengths and the constraints on the size allowable for the protein molecules of organic life, also seem to be tailor-made for each other. This “tailor-made fit” allows photosynthesis, the miracle of sight, and many other things that are necessary for human life. These specific frequencies of light (that enable plants to manufacture food and astronomers to observe the cosmos) represent less than 1 trillionth of a trillionth (10^-24) of the universe’s entire range of electromagnetic emissions. Like water, visible light also appears to be of optimal biological utility (Denton; Nature’s Destiny).

Extreme Fine Tuning of Light for Life and Scientific Discovery (1 in 10^24)- video
http://www.metacafe.com/w/7715887

Michael Denton: Remarkable Coincidences in Photosynthesis – podcast
http://www.idthefuture.com/201....._coin.html

2. 2
Joe says:

The type of star is just one of the many factors required for a planet with inhabitant observers.

3. 3
Barb says:

From the article “The Exceptional Nature of Our Sun,” [Awake!, March 22, 2001]:

It is true that only about half a billionth of the sun’s energy output reaches our planet. Yet, even those few “crumbs” from the solar “table” are enough to nourish and sustain life on earth. Not only that, but if this tiny trickle that arrives could be harnessed efficiently, it could easily meet the energy needs of our modern society, with power to spare.

Most astronomy books say that our sun is an ordinary star, “a rather commonplace celestial object.” But is the sun in every respect a “commonplace celestial object”? Guillermo Gonzalez, an astronomer at the University of Washington in Seattle, has suggested that our sun is exceptional. Should this affect the search for life on other planets? Gonzalez answers: “There are fewer stars suitable for intelligent life than people realise.” He adds: “Unless astronomers narrow down their search to stars as exceptional as the Sun, they are wasting much of their time.”

What are some characteristics that make our sun suitable for nurturing life? As we examine these factors, we should keep in mind that many statements on the physics of the universe are theoretical in nature.

Some of the characteristics include:
1. The sun is a single star. “The case of the sun as a single star seems, then, to be rather unusual,” writes astronomer Kenneth J. H. Phillips in his book Guide to the Sun. That single status of the sun gives the earth a more stable orbit, which, in turn, makes for conditions that contribute to life on this globe, says Gonzalez.

2. The sun is also a massive star. Another related idiosyncrasy of the sun, according to Gonzalez, is that “it is among the most massive 10 percent of stars in its neighbourhood,” reports New Scientist magazine. Phillips notes: “The sun contains 99.87% of the mass of the solar system and as a result gravitationally controls all bodies in the solar system.” This characteristic allows for the earth to be relatively far from the sun—93 million miles [150 million km]—and still not pull away from it. This comparatively large distance, in turn, protects life on earth from being scorched by the sun.

3. The sun contains heavy elements. Gonzalez notes that the sun has 50 percent more heavy elements—carbon, nitrogen, oxygen, magnesium, silicon, and iron—than other stars of its age and type. In this, our sun stands out among its peers. “The abundances of heavy elements in the sun are very low,” says Phillips, “but some stars . . . have even lower heavy-element abundances.” In fact, stars that have heavy-element abundances like that of the sun belong to the specific category called Population I stars.

How does this relate to the existence of life on earth? Well, the heavy elements are necessary to support life. But they are rare, making up less than 1 percent of the universe. Our earth, though, consists almost entirely of the heavier elements. Why? Because, astronomers say, the earth orbits such an unusual home star—our sun.

4. It has a less elliptic orbit. Another advantage arises from the sun’s being a Population I star. “Population I stars are generally performing nearly circular orbits round the centre of the galaxy,” says the book Guide to the Sun. The sun’s orbit is less elliptic than that of other stars of its age and type. Why would that affect the existence of life on earth? Because the circularity of the sun’s orbit prevents the sun from plunging into the inner galaxy, which is frequented by supernovas (exploding stars).

5. The sun has variation in brightness. Here lies another interesting fact about the star of our solar system. Compared with similar stars, the sun has significantly less variation in brightness. In other words, its luminosity is more stable and constant. Such a relatively stable output of light is critical for life on earth. “Our very presence on the planet,” says science historian Karl Hufbauer, “is evidence that the sun’s luminosity is one of the more stable environmental factors.”

6. The tilt of the sun’s orbit. The sun’s orbit is only slightly inclined to the galactic plane of the Milky Way. That means that the angle between the plane of the orbit of the sun and the plane of our galaxy is very small. How does this contribute to the welfare of life on earth? Far beyond the ends of our solar system, a vast spherical reservoir of comets, called the Oort cloud, surrounds us. Suppose that the inclination of the sun’s orbit to the galactic plane were greater. Then the sun would abruptly cross the plane of our galaxy, which could stir up the Oort cloud. What would the result be? The earth would be bombarded with a catastrophic rain of comets, say astronomers.

7. Solar eclipses: Of all the planets in the solar system (yes, I am counting Pluto) the Earth seems to be the only one that enjoys total eclipses. A solar eclipse occurs when the moon comes between the sun and the earth. To get a perfect overlap, the apparent sizes of the sun and the moon have to be roughly the same, so that the moon almost totally covers the sun. And this is exactly the case! Although the sun is 400 times bigger in diameter than the moon, it is also nearly 400 times farther away from the earth than is the moon. But the earth’s distance from the sun—and thus the apparent size of the sun—is more than simply a factor in the forming of a total eclipse. It is also a vital condition for the existence of life on earth.

“If we were a little nearer or farther from the Sun,” Gonzalez says, “the Earth would be too hot or too cold and so uninhabitable.” There is more. Earth’s unusually large moon helps life on this planet because its gravitational pull prevents the earth from wobbling around too much on its axis. Such wobbling would cause wild and catastrophic swings in climate. So to have life on earth, what is needed is an exact combination of the right distance between sun and earth as well as a moon of the right size—and this on top of all the other considerations regarding the nature of the sun.

Suppose you take your car to a trained and skilled technician for a tune-up. He diligently finishes his job, and you find everything to be in order. How do you think he will react if you later insist that the precise tune-up of your car was accomplished by mere accident or that it was the result of pure chance?

The same question may very well be asked about the exceptional nature of our sun. Some scientists would have you believe that the make-up of our sun, its orbit, its distance from the earth, and its other characteristics are all merely a fortunate coincidence. Does this make sense? Do you think it is a logical conclusion?

4. 4

OT: Applying ID to solve the mystery of flight MH370:

http://us.cnn.com/2014/04/29/w.....?hpt=hp_t1

Who is behaving like darwinists?
Who is applying ID reasoning to find the plane?

5. 5
Joe says:

rprado- the only way MH370 is intact is if it landed gently on the water and then sunk

6. 6

Hi Joe – Exactly, similar to US Airways flight 1549 that landed intact on Hudson River 5 years ago.

7. 7
Joe says:

So someone hijacked MH370- be it the pilot, co-pilot or agency yet to be determined, and set it down gently in the Bay of Bengal?

OK maybe that makes sense if the perp had someone waiting to fish him out.

8. 8
Mung says:

There is no such thing as a “typical” star.