365 Days of Astronomy

Gentle Reader,

We’re featured in the latest Carnival of Space (#90?) over at 21st Century Waves!

Also, I’m slow, so check out CoS #89 (The Moon Society Blog), CoS #88 (The Spacewriter’s Ramblings), and CoS #87 (The Martian Chronicles!).

Please stop by if you want a dose of Space news – there’s plenty out there – and you might find a new blog to add to your RSS reader!

~Alice!

So you took a walk last night and you saw two beautiful bright stars. It was the planet Venus and the bright star Sirius, but look out – don’t miss cute little Saturn coming up in the East!

Venus:

So, look up, high in the West after sunset. You’ll see this object that is SO BRIGHT you won’t be able to believe it’s something celestial, but I promise you, it is.

Venus is a planet, not a star, though without a telescope it looks for all the world like a star. It’s truly beautiful, even here in Seattle, and if you’ve got a telescope or a good pair of binoculars you should be able to see that it has a crescent phase, or at least that it’s not perfectly round.

Venus is even bright enough to see it before dark, if you know where to look. Find Venus in the dark night sky one night, and the next night go out just after sunset, or after the Sun is behind a tall building for you, and look a little higher in the sky than you saw it the previous night.

Sirius:

The brightest star in the whole night sky is sparkling low-ish in the South tonight. Its twinkling looks like its flashing redgreenblueredwhiteredbluegreenredbluewhitebluewhiteblue. You might even think it’s an airplane, but watch for a couple minutes and you’ll see it’s not moving.

Saturn:

It’s dim, and rises late – I saw it last week around 8:45pm, but it was pretty stuck in the mucky light pollution over Seattle (from my point of view). If you wait until just a little later it should be higher. The exciting thing about Saturn is that the rings are edge on right now.

Saturn’s rings are tilted in relation to the plane of the solar system. Imagine the desk in front of you is the plane of the solar system. All the planets (except Pluto) orbit within that plane – they stay in the desk as they go around. Now hold your hand up, flat against the desk. Tilt it up. That’s how Saturn’s rings are tilted, just like the Earth’s axis. And just like the Earth’s axis stays tilted the same direction (pointed at the North star), which means that sometimes the North pole is pointed at the Sun, and sometimes it’s pointed away. So, as Saturn rotates around the Sun, sometimes we see the rings almost surrounding the disk of Saturn, and sometimes we see just the edge.

If you look with a small telescope it’s totally worth it, but you’ll have to concentrate to see the hint of the rings.

Alice Enevoldsen

Let it be known that Kevin R. Grazier is a complete geek. He was the first to solve my Twittered/Facebooked riddle:

68 74 74 70 3a 2f 2f 74 69 6e 79 75 72 6c 2e 63 6f 6d 2f 66 65 62 36 62 64 61 79

He won a recipe of my choosing out of my collected recipes. Because.

(What? You wanted one too? Friend me and be on the lookout for geektastic insanity! Sometimes anyway. Especially while I’m grading. And they won’t be as bad as that one, I just happened to be inspired.)

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Well, you probably knew he was a geek. Google him if you don’t know why you should know he’s a geek.

I posted the PowerPoints from the first half of my ASTR 100 class on archive.org.

Try this link, but don’t shoot me if it doesn’t work yet: Astro 100 PowerPoints 1

Here is an incomplete list of the links I’ve used in class – either for images, or for movies. I will go through and make them all more specific, and make sure each is correctly referenced within the PowerPoint, but I wanted to give you something to work with for now.

PPT 1:

The International Year of Astronomy – http://www.astronomy2009.org/

Image of the Sun – http://z.about.com/d/space/1/5/Y/Q/sun_tour.jpg

Image of the Full Moon – http://science.nasa.gov/headlines/y2007/images/christmaseve/moon.jpg

Solar System Diagrams – http://www.cartage.org.lb/en/themes/sciences/astronomy/Solarsystem/TheSolarsystem/solarsystem/RevolutionandRotation/RevolutionandRotation.htm

Alpha Centauri Image – http://heasarc.gsfc.nasa.gov/docs/cosmic/gifs/alpha.jpg

The World at Night – http://www.twanight.org/newTWAN/photos/3001088.jpg

Sagittarius Star Cluster – http://apod.nasa.gov/apod/image/0105/sgr1_hst.jpg

Andromeda Galaxy – http://apod.nasa.gov/apod/ap061126.html

Hubble Deep Field – http://apod.nasa.gov/apod/image/9702/deep_hst_big.jpg

MESSENGER – Earth Flyby Video – http://www.nasa.gov/centers/marshall/mpeg/126252main_mdis_depart.mpeg

PPT 3:

Galileo’s Telescope – http://www.marcdatabase.com/~lemur/lemur.com/gallery-of-antiquarian-technology/philosophical-instruments/galileo-singer/galileo-telescopes-150-434-830.jpg

Types of Telescopes – http://www.uk-telescopes.co.uk/beginners_guide%20to%20telescopes.htm

Refractor – http://mmejia28.wordpress.com/2008/09/07/project-i/

Reflector – http://www.camcentre.co.uk/shop/index.php?act=viewProd&productId=29

Cassegrain – http://www.urbanzeitgeist.com/tech/orion_atlas_11_eq_schmidtcassegrain_telescope.html

Atmospheric Absorption – http://www.everythingweather.com/atmospheric-radiation/transmissionwindow2.gif

Hubble – http://apod.nasa.gov/apod/image/9703/hubble_sts82.jpg

Chandra – http://chandra.harvard.edu/graphics/resources/illustrations/chandra_trw_300.jpg

James Webb – http://jwst.gsfc.nasa.gov/images_jwst.html

PPT 5

Electromagnetic Spectrum – http://www.antonine-education.co.uk/physics_gcse/Unit_1/Topic_5/em_spectrum.jpg

Energy Levels – http://www.physics.uiowa.edu/adventure/fall_2005/oct_15-05/energy_levels.gif

Energy Levels – http://www.upei.ca/~physics/p261/projects/nuclear2/images/energylevel.gif

Absorption and Emission Spectra – http://www.physics.umd.edu/courses/Phys401/bedaque06/discrete_spectra.jpg

Solar Spectrum – http://fsf.nerc.ac.uk/img/g37_grph.gif

Absorption vs Emission vs Black Body – http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap04/FG04_07.jpg

Spectral Types – http://antwrp.gsfc.nasa.gov/apod/image/0105/obafgkm_noao_big.jpg

Red Shift & Blue Shift – http://odin.physastro.mnsu.edu/~eskridge/astr101/kauf5_23.JPG

Fire Engine Doppler Effect – http://www.youtube.com/watch?v=imoxDcn2Sgo

The Big Bang Theory talks about the Doppler Effect – http://www.youtube.com/watch?v=J43lAESftPs

The Laboratory of the Devil: Doppler Effect – http://www.youtube.com/watch?v=-t63xYSgmKE

Onwards. I’ll finish these up later.

http://www.eso.org/gallery/d/4380-2/phot-28c-07.jpg

http://raviramanathan.blogspot.com/2007/05/life-cycle-of-star.html

http://video.google.com/videoplay?docid=-6732533372822687572&ei=c_iASe30OZ64qAPS-MSVDg&q=slinky+compression&hl=en

http://people.maths.ox.ac.uk/schmitz/Files/starlife.jpg

http://fora.tv/2008/02/19/Neil_DeGrasse_Tyson_Death_by_Black_Hole

Oops. We’ve been teaching meteors wrong. I’ll bet it’s my fault.

The Short:

Meteors do not heat up due to friction with the atmosphere, unlike what our classic hand-rubbing demonstration leads you to believe. They heat up due to compression of the atmosphere. Mostly.

The Story:

So imagine a boat speeding across Lake Washington. See that bow shock, the beginning of the wake, which forms in front of your imaginary boat? That’s kinda what’s happening. Of course, water doesn’t compress (being a liquid), so you get up-and-down waves in water instead of compressed density waves, but gas like an atmosphere is VERY good at compressing, so for our meteor we’ll get nice compression. The speeding meteor-particle (yes, the tiny sand-sized piece of rock) compresses the air in front of it, like the boat’s bow shock.

Bow Shock

Density Waves:

We talked about density waves a little while ago when we were discussion the galaxy. Instead of up-down or side-to-side waves, density waves are just more stuff or less stuff in a given area. In the case of compression heating, we’re squishing more stuff (air) into a smaller area.

Compression Heating:

When you compress a gas it heats up. Well, almost always. There are some weird cases, but this isn’t one of them. This is classic PV=nRT. What?! Am I allowed to write that on the internet? Yes. This is one of the things you learn early on in a chemistry class that has even a little math in it. Basically the Pressure and Volume of a gas are directly related (=) to the number of atoms, R (just a number), and Temperature. So, if you change one of those things, the others have to change too… oh, and you can’t change n or R.

Alice, I’m not listening anymore:

Okay, come back. This is why a bicycle pump heats up when you’re pumping. It’s not the friction of the little thing inside, it’s that you’re pressurizing gas. This is why aerosol cans (shaving cream, hairspray, those compressed air cans you get for dusting out your computer) cool off when you use them.

The New Way:

You can still do hand-rubbing. Until we come up with a kinesthetic way to teach compression (suggestions?), you might as well – we’re still talking about heat, and that’s a great demonstration of heat. Just mention that it’s not friction that burns up the meteor – it’s compression heating (like a cooling aerosol can).

Alice Enevoldsen

Want More?

Thanks for tipping me off Phil.

Here’s some more from NASA.

Lookie!

Wow. BBC – huh. Their date for that clip is November 08. Well, that video of me is from … either _early_ 2008 or back in 2007 … or was it before that? I don’t remember – it wasn’t the November 08 or the ephemeral “recent” one – I didn’t report on either of those, but my clip got picked up for the one in November.

Especially since I was in FLORIDA enjoying the SUN when this happened…

Though it wasn’t before May of 07, because that’s how long my hair’s been blue!

Yay for becoming international!

Tip o the video camera to Phil Plait!

Scientists detected methane in Mars’s atmosphere. In fact, they’ve been detecting it for years. Methane should dissipate from the atmosphere in that time, but it didn’t. This means something on Mars is creating more methane. There are two giant ways to make methane:

1) Life (you know, even at the cellular level)
2) Geology (chemical reaction)

Either one of these is cool. We know there is a little geologically happening on Mars, but it seems fairly dead. Finding methane means that there are chemical processes going on.

It does NOT mean there is life on Mars. It could, but it’s WAAAAY more likely to be geology.

Read more from Emily.

Our universe is not only expanding – but that expansion is accelerating. It’s expanding faster and faster and faster. When you’re driving your car you don’t speed up for no reason – either you step on the gas, you’re rolling down a hill, you get slammed from behind, or your engine suddenly and unexpectedly starts feeding gas to the engine (I hope not!). The universe’s expansion can’t speed up for no reason either. That energy MUST come from somewhere – but we don’t know where, so we’re calling this extra energy “Dark Energy.”

Law of the Universe:

You cannot create energy from nothing. Just like you wouldn’t expect to see a kitten materialize out of nothingness and appear on your keyboard (it might jump there, but not materialize!), you can’t get energy out of nothing. It all comes from somewhere. This is called the law of conservation of energy. Sometimes it’s called the first law of thermodynamics.

The Universe is Accelerating:

From our measurements of Type 1a supernovae we know that the universe is expanding and that expansion is accelerating. Basically, those supernovae are farther away than our physics models predict them to be, and there’s not enough energy in the Universe to do that.

Cosmological Constant:

Einstein proposed a “cosmological constant” to solve a similar problem many years ago. Then he changed his mind and gave it up. With our new observations, it’s back in play now. Under this hypothesis, a specific volume of space (the cosmos) always (constantly) has a given amount of energy in it. Say you had one cubic meter of space. Under this theory, it would have … let’s say an amount “5” of energy. Then, over time the universe expands and now, your one cubic meter of space now takes up two cubic meters. Because of the cosmological constant, that space would have an amount “10” of energy. By definition. Just because it is space. (Usually we do this with variables in astronomy, but I wanted to be clear). Pretty weird, but you get lots of extra energy.

Quintessence:

What if Dark Energy is not constant? What if it changes over space and time? You’ve got a little more here, a little less there. There was more last year than there will be in a billion years. That’s the quintessence hypothesis. Maybe it’s particles (like photons and electrons), or maybe it’s a field (like the magnetic field of the Earth), but in any case it changes, it’s not constant.

New Physics:

And, not to be forgotten, what if our equations for Physics are just wrong? What if we need to completely rethink them? In any case, the universe is accelerating in its expansion, so until we know what is making it do that, we’re just going to call it Dark Energy.

P.S. Ghosts are not made of Dark Energy. That’s crazy talk.

Want More?

Pamela Gay “Dark Energy is Real”
Ethan Siegel
Astronomy Cast and 365 Days of Astronomy
Sky and Telescope, February 2009 “Going over the Dark Side” – More Info

Alice Enevoldsen

#86 is at collectSPACE – and features your favorite Alice’s Astro Info as hit number 2!

#85 is at Cheap Astronomy – and I’m not in it, but other awesome people are!