Rocket Science for the Rest of Us

Thanks, everyone, for your patience.  What a summer it has been!  I think I'm back on my feet now, so let's catch up on our space studies.  If you've been following the lessons in the sidebar--congrats!  Hope you get a little refresher on those things we missed.

Doppler Effect. Lesson 6.4 here:  http://www2.jpl.nasa.gov/basics/bsf6-4.php

I have to admit, I always have a hard time wrapping my head around this one, and the little pulse graphics don't help me.  I prefer to visualize it as a wave--like a slinky, for example.  If you hold one end still and move the other in an even up-and-down pattern, you get a wave of a certain length and frequency.  Now move one end away from the other, but don't change the rhythm of the up-and-down motion.  Your frequency stays the same, but the wavelengths are longer.  The difference in the wavelengths is your Doppler shift.

Paul Hewitt explains it very well--and he's funny, too.

We hear Doppler shifts all the time--the most common example is in how a train whistle or a siren sounds higher when approaching and lower when moving away.

Doppler shifts are great for telling position and distance--or how fast you are speeding down the highway.  Come back tomorrow, and I'll tell you a funny story involving Doppler shift, my father, and my husband.  For now, let's move on. 

Reflection of Radio Waves: Lesson 6.5 here:  http://www2.jpl.nasa.gov/basics/bsf6-5.php

This is a pretty basic lesson, and a phenomenon we are all familiar with, although I didn't know about the skipping phenomenon with x-rays. What the lesson doesn't tell you, either, is how x-ray astronomy is giving us a whole new look at the universe.



Refraction:  Lesson 6.6 here:  http://www2.jpl.nasa.gov/basics/bsf6-6.php

Again, this is a common phenomenon on earth, but it's cool to see how it's being used in space exploration.  I wonder if that's how tricorders are supposed to work when analyzing atmosphere, etc?  (I'll need to check out The Physics of Star Trek, if I can find it in my husband's library.)

The lesson is here: http://www2.jpl.nasa.gov/basics/bsf6-3.php

Another straightforward lesson about the spectrum, how it's categorized and why its useful to study it.  In short, certain elements can absorb specific frequencies, so by getting a spectral reading, we can determine the composition of the planet.  It's also an important science for asteroid mining.  (This is an old article, but explains why.  This month's Popular Mechanics has a terrific article on asteroid mining.  I'll review it later.)

Link to Lesson:  http://www2.jpl.nasa.gov/basics/bsf6-2.php

Once again, we're getting some basic concepts that are used in engineering and astrophysics.  It's been interesting, though, because I learned a couple of things.  I'd heard that light is the only thing that is described both as a wave and a particle.  When I'd not realized is that anything on the electromagnetic spectrum (like radio signals) can be described the same ways.  It's just that the particle idea is better used when you start getting into the spectrum of light.

I didn't really know what decibels were, so this lesson was good for that.  However, it's been a long time since I've worked with logarithms, so I did some looking on YouTube.  Here are two to share with you. 

Decibels explained on an engineering level: This one is good for showing why decibels are useful as well as what they are.

Decibels explained on a more elementary level:  This one gives a little history.

Lesson: http://www2.jpl.nasa.gov/basics/bsf6-1.php

Just one thought on this one--relief.  For some reason, I had it in my head that all the music, TV, YouTube vids, etc that we've been broadcasting were going to be heard by some alien race, but thanks to the inverse-square law, they are probably too faint to hear outside the "local" area.

Of course, that removed the argument that there is life out there, they have seen Jersey Shore*, and they have no intention of contacting us. Ever.


* My daughter picked this show.  I had Gilligan's Island, but that's too old.  My next thought was Parks and Rec, although I'm sure there are many worse than either of these.  Like I said, relief.