Tag: Stars

Science Can’t Explain Everything

~ J.S. Pailly ~ 6 Comments

Hello, friends!

As you know, I love science.  I’m a little obsessed.  But there are people who get annoyed or even offended by my obsession with science, and every once in a while one of these people will remind me, sternly, that science can’t explain everything.  And you know what?  I generally agree with that sentiment.  But then people start declaring that science will never know this specific thing or that specific thing, and I immediately think of a certain 19th Century French philosopher named Auguste Comte.

Comte was not some scientifically illiterate buffoon.  He wasn’t one of those 19th Century evolution deniers, or one of those latter-day opponents to the heliocentric model of the Solar System.  In fact, Comte is regarded today as the very first philosopher of science, in the modern sense of that term, and he gets credit for coining the word “sociology” and for laying the philosophical foundation for that entire branch of science.  There’s also a wonderful quote from Comte about the mutual dependence of scientific theory and scientific observation.  Basically, you can’t formulate a theory without observation, but you also can’t make an observation without the guidance of a theory.

But that is not the Comte quote I think of whenever somebody starts lecturing me about the things science will never know.  It’s this quote about the stars: “[…] we shall never be able by any means to study their chemical composition or their mineralogical structure…”  Comte also declared that: “I regard any notion concerning the true mean temperature of the various stars as forever denied to us.”

Comte wrote this in 1835, and if you can put yourself into an 1835 mindset you can see where he was coming from.  There’s no such thing as rocketry.  We don’t even have airplanes yet.  And even if you could fly up to a star (or the Sun), how would you measure its temperature?  What kind of thermometer would you use?  And how would you go about collecting stellar material, in order to determine the star’s chemical composition?

According to Comte—a highly intelligent and very pro-science person—this sort of knowledge was utterly impossible to obtain.  And yet only a few decades later, thanks to the invention of the spectroscope, scientists started obtaining some of this unobtainable knowledge.  For those of you who don’t know, spectroscopes separate light into a spectrum.  Some parts of the spectrum may appear brighter or darker than you might otherwise expect, depending on which chemical substances emitted or absorbed the light before it reached the spectroscope.  And so by comparing the spectral lines of chemicals we have here on Earth to the spectrum obtained from the light of a star, you can determine the chemical composition of that star.

You can also measure a star’s temperature thanks to a concept known as black body radiation.  Basically, black body radiation refers to the fact that things glow as they got hotter.  If no other light sources are involved, then the color of a glowing object will be directly related to that object’s temperature.  Ergo, if you know what color a star is, then you can work out a pretty accurate estimate of what temperature that star must be.

Auguste Comte didn’t foresee any of this.  It is certainly true that science does not know everything, and there are surely things that science will never know.  But if you think you know, specifically, what science can never know, I question that.  Someday, some new invention (like the spectroscope) or some breakthrough discovery (like black body radiation) may turn an utterly unknowable thing into a matter of trivial measurements and calculations.

Maybe the one thing science truly can never know is what science’s own limitations are.

WANT TO LEARN MORE?

Here’s a very brief post about Auguste Comte, what he said about stars, and how epically wrong he was with that one prediction.

Also, here’s a short article about some genuine limitations that science has, like aesthetics, moral judgements, etc.

Sciency Words: Coatlicue

~ J.S. Pailly ~ 4 Comments

Today’s post is part of a special series here on Planet Pailly called Sciency Words.  Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

COATLICUE

You may recall the famous words of Carl Sagan: “We’re made of star stuff.”  Turns out we’re not made of just any old star stuff.  No, a great deal of our stuff came from one star in particular, a giant star named Coatlicue that went supernova about 4.5 billion years ago.

I first saw this name in a recent article from Scientific American called “The New Biography of the Sun,” which in turn referenced a paper from the journal Astronomy & Astrophysics titled “Solar System Genealogy Revealed by Extinct Short-Lived Radionuclides in Meteorites.”

In short, certain radioactive isotopes found in our Solar System can be thought of as our Solar System’s D.N.A.  The authors of that “Solar System Geneaology” paper used some of those isotopes (most notably aluminum-26) to try to reconstruct our Sun’s family tree and give us some idea about what the Sun’s “mother” must have been like.

Coatlicue would have been a giant star, approximately 30 times as massive as our Sun, ensconced within a giant molecular cloud along with other giant star siblings.  This is sort of like what we see today with the stars of the Trapezium inside the Orion Nebula.

About 4.5 billion years ago, Coatlicue went supernova.  The explosion accomplished two things: it seeded the surrounding molecular clouds with heavy elements (like aluminum-26) and, because of the force of the explosion, caused those molecular clouds to compress, triggering new star formation.

I have to confess that I feel like there’s a lot of guesswork and speculation going on here about how, specifically, Coatlicue died and how, specifically, the Sun and its planets were born.  But the general idea that the death of one star triggers the formation of others is consistent with what we already know about star formation, so it makes sense to me that something like this must have happened for our own Solar System.

As for the name Coatlicue (which I believe is pronounced Kwat-LEE-kway), that comes from Aztec mythology.  Coatlicue was the mother of the Sun.  So that makes sense.  In the myth, Coatlicue was also the mother of the stars, which actually sort of matches up with the science too.  That supernova explosion 4.5 billion years ago would have triggered the formation of other stars—perhaps several hundred of them—in addition to our own Sun.

I didn’t see this in either Scientific American or that “Solar System Genealogy” paper, but I’d like to believe Coatlicue might not have been totally destroyed in that supernova.  Perhaps some remnant is still out there, living on as a neutron star or a black hole or something.  If so, I doubt we’ll ever find it, but if I know anything about mothers, I’m sure our Sun still hears from Coatlicue every now and then.

Sciency Words: Spectroscopy

~ J.S. Pailly ~ Leave a comment

Welcome to a special Saturday edition of Sciency Words, because sometimes life gets in the way of regular blogging schedules. Each week (normally on Fridays) we take a closer look at some science or science-related term so we can all expand our scientific vocabularies together! Today’s term is:

SPECTROSCOPY

What color is it? It sounds almost like a childish question, but as we look out into space, trying to study the Sun and other stars and distant planets, we can learn a great deal just by figuring out what color things are.

The science of spectroscopy has a long history, beginning with Isaac Newton. In the late 1600’s, Newton demonstrated that pure white light can be split apart into a rainbow of color using a prism. Newton called this a spectrum, from the Latin verb specto, meaning “I observe” or “I see.” (According to my trusty Latin-English dictionary, the noun spectrum also meant “apparition” or “ghost.”)

Over the decades and centuries to come (click here for a detailed timeline), scientists used increasingly sophisticated combinations of lenses, mirrors, and prisms to study Newton’s spectrum in greater detail. They also experimented on a wide variety of light sources: sunlight, starlight, firelight, and even electrical sparks.

An especially noteworthy experiment in 1752 showed that burning a mixture of alcohol and sea salt produced an unusually bright yellow band in the middle of the spectrum (we now know this to be a emission line for sodium). And in 1802, another experiment on sunlight revealed multiple dark bands in the Sun’s spectrum (which we now know are absorption lines for hydrogen, helium, and other elements in the Sun’s photosphere and corona).

All the colors of the rainbow, except a few are missing. This is an absorption spectrum.

It wouldn’t be until the early 20th Century, with the development of quantum theory and, specifically, Niels Bohr’s model of the atom, that anyone could explain what caused all these spectral lines.

No rainbow, just a few specific colors. This is an emission spectrum.

In Bohr’s atom, the electrons orbiting an atomic nucleus can only occupy very specific energy levels. When electrons jump from one energy level to another (the true meaning of a quantum leap), they either emit or absorb very specific frequencies of light. The light frequencies are so specific that they act as a sort of atomic fingerprint.

And so today, as we look out into the universe, seeing the glow of stars and the absorption patterns of planetary atmospheres, it’s possible for us to identify the specific chemical elements we’re seeing, even across the vast distances of space, simply by asking what color is it?

Sciency Words: Metallicity (An A to Z Challenge Post)

~ J.S. Pailly ~ 11 Comments

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, M is for:

METALLICITY

Astronomers. All the other scientists had a meeting, and they all agree: there’s something wrong with those astronomers. For some reason, astronomers do not understand what is or is not a metal.

According to astronomers, the only elements that aren’t metals are hydrogen and helium.

Now it does make sense for hydrogen and helium to be special in astronomers’ eyes. By mass, something like 75% of the observable universe is hydrogen. Helium makes up almost all of the remaining 25%. And the hundred-plus other elements on the periodic table? All combined, all that other stuff constitutes less than 1% of the observable universe.

So for astronomers, it’s convenient to have a word that lumps all this “other stuff” together. But why does that word have to be metal? I’ve never found a wholly satisfactory answer for this, but I do have a personal theory.

Turns out that in technical shorthand, the amount of “other stuff” in a star is represented as [Fe/H]. That’s the chemical symbols for iron (Fe) and hydrogen (H). In other words, the amount of “other stuff” is quantified as a ratio (sort of) of iron to hydrogen (the math is a little more complicated than a simple ratio, but I won’t to get into that here).

I’m guessing that out of all the non-hydrogen, non-helium atoms you might expect to find in a star, iron must be the easiest—or at least one of the easiest—to identify with a spectroscope, and thus iron serves as a convenient proxy for everything else.

The quantity represented by [Fe/H] is called metallicity. Everyone would agree that iron is a metal, so that makes sense. But since metallicity actually tells us more than just the iron content of a star—since it also gives us a sense of how much carbon and silicon and argon etc is in that star—suddenly the word metallicity is covering metals and non-metals alike, in a way that comes across as very odd to everyone who isn’t an astronomer.

Next time on Sciency Words: A to Z, an electron by any other name would still be negatively charged.

Sciency Words: Magnetar

~ J.S. Pailly ~ 10 Comments

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

MAGNETAR

Space has a lot of cool ways to kill you. This one’s especially nifty! Magnetars are neutron stars with intensely powerful magnetic fields. Like, absurdly powerful magnetic fields.

Fly your spaceship near a magentar, and that overpowered magnetic field will start pulling the electrons off your atoms. This will kill you. It’ll destroy your spaceship too. Without those electrons, chemical bonds don’t work. Your molecules will unravel, and you and your ship will just disintegrate.

Even from a distance, magnetars are a menace. In 2004, a strong burst of gamma radiation washed over Earth, compressing our planet’s magnetic field and partially ionizing our atmosphere. That gamma radiation came from a magnetar on the other side of the galaxy.

If a magnetar could do that to us from so far away, just think what it must have done to any alien civilizations that happened to live closer. I can’t help but imagine there’s a vast dead zone on the other side of the galaxy, with magnetar SGR 1806-20 right in the middle.

The good news is that magnetars don’t last long. Their magnetic fields decay rapidly, so these raging monsters turn into regular neutron stars within a few thousand years. Also, while their outbursts of gamma rays and X-rays can affect our planet, there aren’t any magnetars close enough to Earth to really threaten us.

Oh wait. Yes there are. Sort of.

Sciency Words: Frost Line

~ J.S. Pailly ~ 10 Comments

Welcome to a very special holiday edition of Sciency Words! Today’s science or science-related term is:

FROST LINE

When a new star is forming, it’s typically surrounded by a swirling cloud of dust and gas called an accretion disk. Heat radiating from the baby star plus heat trapped in the disk itself vaporizes water and other volatile chemicals, which are then swept off into space by the solar wind.

But as you move farther away from the star, the temperature of the accretion disk tends to drop. Eventually, you reach a point where it’s cold enough for water to remain in its solid ice form. This is known as the frost line (or snow line, or ice line, or frost boundary).

Of course not all volatiles freeze or vaporize at the same temperature. When necessary, science writers will specify which frost line (or lines) they’re talking about. For example, a distinction might be made between the water frost line versus the nitrogen frost line versus the methane frost line, etc. But in general, if you see the term frost line by itself without any specifiers, I think you can safely assume it’s the water frost line.

Even though our Sun’s accretion disk is long gone, the frost line still loosely marks the boundary between the warmth of the inner Solar System and the coldness of the outer Solar System. The line is smack-dab in the middle of the asteroid belt, and it’s been observed that main belt asteroids tend to be rockier or icier depending on which side of the line they’re on.

It was easier for giant planets like Jupiter and Saturn to form beyond the frost line, since they had so much more solid matter to work with. And icy objects like Europa, Titan, and Pluto—places so cold that water is basically a kind of rock—only exist as they do because they formed beyond the frost line. This has led to the old saying:

dc23-outer-solar-system-christmas-party

Okay, maybe that’s not an old saying, but I really wanted this to be a holiday-themed post.

Sciency Words: Flare Star

~ J.S. Pailly ~ 7 Comments

Sciency Words BIO copy

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us all expand our scientific vocabularies together. Today’s term is:

FLARE STAR

Good Star Trek fans will remember the Battle of Wolf 359, when the Borg came to assimilate us all. Thirty-nine Federation starships were lost. Nearly 11,000 people were killed. #NeverForget

Good Trekkies may also be aware of the fact that Wolf 359 is a real place. It’s a red dwarf star in the constellation Leo, located within a mere eight light-years from Earth.

Also, Wolf 359 is a UV Ceti variable star, or what is more commonly called a flare star. Flare stars experience dramatic, unpredictable increases in brightness across the EM spectrum, including increases in highly destructive X-ray and gamma ray emissions.

And when a flare star starts to flare up, it can happen quickly. In 1952, the star UV Ceti (for which the UV Ceti variable star category is named) became about 75 times brighter in a period of only twenty seconds.

It’s believed that the flare activity of flare stars is similar to the kind of solar flares we’ve observed on our own Sun. Except the Sun’s solar flares are usually not so intense. And when it comes those X-rays and gamma rays, our Sun doesn’t even come close to what spews out of flare stars.

So perhaps parking thirty-nine starships next to a flare star wasn’t the smartest thing Starfleet could have done. Maybe… just maybe… what happened at Wolf 359 wasn’t the Borg Collective’s fault.

Ag26 Battle of Wolf 359

P.S.: Another flare star has been in the news a lot lately: Proxima Centauri. We now know, thanks to the European Southern Observatory, that Proxima does have an Earth-like planet in orbit. So the next question is just how thoroughly that planet has been cooked by Proxima’s violent flare-ups.