Date: September 10, 2011

Title: Measure the Sun

Podcaster: Sandy Antunes

Organization: Project Caliope

Links: http://projectcalliope.com
Email: antunes@nasw.org

Description: Is the Sun a glowing yellow ball, or far more? What exactly can we measure about it? Does measurement detract from beauty, or enhance it? And what exactly is a creepmeter?

Bio: Dr. Sandy is launching a personal science/music satellite at projectCalliope.com, writes twice/weekly at Science2.0, and has just accepted a professorship at Capitol College.

Sponsors: This episode of “365 Days of Astronomy” is sponsored by John Sandlin. The Sandlin Family wishes you all clear skies.

This episode of “365 Days Of Astronomy” has also been brought to you by thesecretlair.com The Secret Lair is an online magazine and podcast dedicated to world domination and the plight of the grown-up geek. From an undisclosed location near Cleveland Ohio, Overlord Chris Miller, Dr. John Cmar, Commandant David Moore, and Secretary of Artistic Propaganda Natalie Metzger are joined by a stellar cast of contributors to share with you the trials, travails, and trivia of being a modern day working stiff with a strong escapist streak. There are lots of places covering pop culture on the Internet. We bring a midwestern Everyman look at the world around us. If you find yourself somewhere between the ages of 20 and 60, have to deal with the responsibilities of paying for a roof over your head, credit card bills, car payments, and possibly raising kids, but you still like to read, play games, and talk with other mature adults about your obsession with Star Wars, drop by The Secret Lair. We’ll leave the lights on… and the portcullis up.

Transcript:

This is Dr. Sandy Antunes, the Daytime Astronomer, here at “365 Days of Astronomy”. You can read me each week at ProjectCalliope.com

Do you know what a creepmeter measures? Measurement is the heart of science. What distinguishes science from opinion or philosophy is measureables. The root of science is facts, facts that are determined by actual observation, then compared, then extended into predictions.

Now, any good measurement has three parts: the number value, the units you’re using, and the error. If I say I am 6 feet tall, that’s a number (6) and a unit (feet), with a presumed error of ‘within an inch or two’. All three parts are crucial.

For example, if you want to know how fast your car is going, a number can be a useless answer. My car’s speedometer shows both miles per hour (MPH) and kilometers per hour (KPH). I trust it’s accurate to within a few miles per hour (or a few kilometers per hour). If I just read a number, though, I could be in trouble.

A speed of “90” may or may not be lawful if it’s a 65MPH highway. Is that 90MPH, or 90KPH? 90MPH means I get a $200 ticket, but 90KPH means I’m the slowest car out there. So units matter.

One question I ask my physics students is what can you measure on the Sun? We often think of the sun as a big glowing yellow ball in the sky, but the Sun is a complicated entity. It’s called an active star, and for a reason. Think about everything you might be able to measure. We’ll get back to it in a moment.

While you’re thinking, NASA released a 3D Sun iPhone app. This is way fun. Playing with a digital sun can be as interesting as a game. I recommend you take a look at this free app. Twirl the sun around, look at different layers, and let it sink in that it’s all real. Everything you’re looking at is real data from the STEREO spacecraft.

Still thinking about measurements of the Sun? Your opinion might change if you also note that the Sun is both active and rotating. It’s more than a just big yellow ball in the sky that you see. It’s this fiery rotating dynamic orange thing that throwing off bits of plasma, huge amounts of ultraviolet light, X-ray emission, lots of stuff going on.

While you’re making your little thought list of everything you can measure about the Sun, here’s a look at things– solar and not– that engineers use to measure things. A peek at the Wikipedia “list of measuring devices”, it’ll reveals the insane number of existing gadgets for measuring things. Here’s just the list from A to C:

accelerometer for acceleration
actinometer heating power of sunlight
alcoholometer alcoholic strength of liquids
altimeter altitude
ammeter electric current
anemometer windspeed
atmometer rate of evaporation
audiometer hearing
barkometer tanning liquors used in tanning leather
barometer air pressure
bettsometer integrity of fabric coverings on aircraft
bevameter mechanical properties of soil
bolometer electromagnetic radiation
calorimeter heat of chemical reactions
cathetometer vertical distances
ceilometer height of a cloud base
chronometer time
Hey– that’s a watch!
clap-o-meter volume of applause
colorimeter colour
creepmeter slow surface displacement of an active geologic fault in the earth

[breath] Et cetera, et cetera.

There may be ‘more things on Heaven and Earth’ than we can measure, but there’s no shortage of devices to measure by. Have you finished your list of sun measureables yet? Just off the top of my head, I hope you included size– aka the volume and the distance to it. It’s mass, and temperature. Density and surface area are worth noting. Also, it’s rotating, so measure that. Also light output, perhaps broken out by spectrum, the amount for each ‘color’, all the way from radio through visible light and up to X-rays and gamma rays. The particle emission, too. Again, temperatures are obvious. The hemical composition– what elements exist, including its metallicity. Metallicity is defined as ‘everything other than Hydrogen, H, and Helium, He.

The sun has strong magnetic activity, so you’ll want to measure the magnetic field and the electric field. You’ll want to measure the sound waves that go through it, and perhaps add some helioseismology. The opacity– how transparent parts of it are. The rate of fusion (or the conversion of H to He + heat), you can measure that. The particle emissions, from high energy stuff to neutrinos, are measureable.

You can derive values such as its gravity (from its mass) and its age (from a variety of things). The sun is moving through the galaxy so you can measure that. Basically, the sun is joyfully complex. Given the sun has layers, we’ll want to measure all these properties at different layers. The rotation is at different speeds at different distances from the solar equator, and in fact most of the things you measure change with time as well as where it occurs in the sun. Add in transient activity– loops, flares, Coronal Mass Ejections, and other brief yet potent events– you have more to measure. The wonders never cease!

If you want to be boring, you can always fall back on the most basic measurements: size, mass, the fact that it looks yellow, and whether it’ll set you on fire or not.

Some may say measuring detracts from something. I think when you take something we presume is simple, such as the sun, and you measure and find out how awesomely complex it is, that just adds to the fascination of life.

This is Dr. Sandy Antunes, the Daytime Astronomer, here at 365 Days of Astronomy. You can read me each week at ProjectCalliope.com. Until next month, enjoy measuring.

End of podcast:

365 Days of Astronomy
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