Shower Time!

Hi! It's been a while since I've posted (if you're interested in my excuses, let me know.... No? Didn't think so!)

Anyway, nothing like a good meteor shower to bring me out of hibernation. The Perseids are set to peak tomorrow, so tonight, tomorrow morning, and tomorrow night might be good times to look for them. The weather around here is predicted to be pretty good, though maybe a bit hazy.

The radiant of the Perseid meteor shower (the point in the sky where the meteors appear to come from) is in Perseus*, and will rise in the northeast a bit before 11 pm both nights. Unfortunately, the moon also rises about the same time, and once the moon is up, it will make the fainter meteors hard to see. If you block the moon with your hand or a tree or a house, it may help.

Moonlight is not the only problem. Try to find a dark location, away from city lights, to watch for meteors. The darker the sky, the more meteors you will see, and the more spectacular they will look. Also when deciding on your watch location, consider the fact that you will be looking toward the northeast to see the shower. You don't want to go southwest of town, then turn around and look back toward the city lights to see the show!

Why do we get a meteor shower every year at about this time? Well, meteors are just objects from space hitting the earth's atmosphere and burning up brightly. Every year, on our trip around the sun, the earth passes through the orbit of comet Swift-Tuttle - the comet isn't there when we are there, but the debris it left behind from its tail is there, and that is the stuff that burns up in our atmosphere and gives us the show called the Perseid Meteor Shower.

Enjoy!

*_{I personally don't recognize the constellation Perseus, but I do recognize Cassiopeia, which is shaped like a W. The radiant will rise just below Cassiopeia.}

News

Update - trebuchet photo below


* The Perseid meteor shower should be good this year, because of the new moon. Watch for meteors emanating from the northeast late Sunday night (Aug 12th) and the wee hours of Monday morning (13th). If possible, get out in the country, preferably northeast of town, so you have dark sky to view the meteors against. FYI, the Perseid meteors are the dregs left behind by comet Swift-Tuttle. As the earth passes through these tiny bits of comet dust, they burn up in the atmosphere, glowing briefly and beautifully.

*Our new faculty members, Jim van Howe and Joe Owczarzak, are now here in the QC and getting ready to start the fall term. It's going to be an exciting year!

*The trebuchet will arrive at the science building around noon tomorrow, if you want to come see it. (Blogger spell-check doesn't know the word trebuchet!)

*Anyone planning on taking the GRE this fall, let me know - you can join our prep sessions.

*It's only a ball, for crying out loud. "...the ball... wound up in the hands of ...Matt Murphy ... he was bloodied and his clothes torn ...."

Leonid Meteor Shower Tonight!

The Earth will be passing through the heart of the debris left by the tail of comet Tempel-Tuttle. This debris burning up in our atmosphere should produce quite a show of meteors in the sky. For the US, the best time to watch for meteors will be in the early morning hours on Nov 17.

Find your way out to the country if you can, and find a dark sky away from the light pollution prevalent in cities.

The radiant (or apparent source) of the meteor shower rises about local midnight (wherever you are), so don't expect to see anything before that. The radiant will rise in the east, but the meteors will shoot in all directions, so if your eastern sky is lit by a nearby town, you may want to look a different, darker direction.

Looks like it will be cloudy here tonight - hope you have better luck with clear skies! You may want to look for remnants of the meteor shower in the early morning hours on the 18th, if your weather is bad tonight.

Physics Club Meeting Minutes

Below are today's meeting minutes, courtesy of Alaina, including these fast-approaching events:

Next Tues (Feb 13): Sigma Xi panel discussion of meteors, mass extinctions and obesity.

Next Thurs (Feb 15): Meetings of the Open House and Button Committees (more members are welcome to join these committees).

Next Sunday (Feb 18): Visit QCElite Robotics test and media days.


Physics club meeting minutes from Feb 8th:

Virtual Reality
-We will be going to the John Deere Tech Center to see their VR on March 29th around 3:30 p.m.
-We will still try to go to Iowa State Virtual Reality place, once it is open again.

Open House
-Possibly April 15th
-Open House commitee will meet next Thursday at 11:30m in room 120 in the Science building.
-Open House commitee is Jake, Jenna, Laura, Alaina, and Gabe

T-Shirts
-Jenna and Laura are still working on ordering this year's shirts.

Buttons
-The button commitee is Jess and Alaina. We will create buttons to give out at open houses and such.

Robot Test Day
-Feb 18th
-We will meet in room 120 for rides around 3.

Augustana Science Day
-Jenna suggested that we have an Augustana Science Day were all the science groups set up and run a couple of demos. This will be on April 22nd, 29th or May 6th.

-Jake will also set up and moderate a Rube Goldberg contest that will end on whatever day the Sci. day is.

Next Tuesday there is a Sigma Xi meeting. They will be showing a Nova special and there will be a panel discussion afterward. We will meet in room 120 at 6:30 for rides.

Meteor Shower Thursday Night!

The Perseid meteor shower, a yearly event, is likely to be particularly good this year because there will be no moonlight in the sky to wash out your view.

What should you do to get a good meteor shower experience on Thursday night?

Step 1: Go out after 11 pm*, preferably after midnight (So, I guess that's technically Friday morning).

Step 2: Find a spot with a good dark sky. If you live in town with the glow from city lights messing up your view, head to the northeast. That way, when you are watching the shower in the northeast, the lights will be behind you.

Step 3: Face northeast, relax, and watch the show. Don't focus on any one spot in the sky, but let your eyes take in a wide view, because you never know exactly where the next one will shoot across the sky.

Step 4: Don't get discouraged if you aren't constantly bedazzled by meteors shooting left and right. This isn't a fireworks show. You might expect a meteor every few minutes, some of which you will miss, especially if your skies aren't very dark.

Step 5: Let me know how it went!

Other showers during the year can be found at StarDate meteor page, or stay tuned here!

*_{local time}

Monday's Lesson is Hot!

This time of year, I'm not usually worried about it, but when I do need a layer of thermal protection, it is protection against the cold. Not so the space shuttle - it needs thermal protection against the heat of re-entry.

You have probably heard in the news that the space shuttle's thermal protection system has once again been damaged during launch. Why is that such a big deal? To answer that, let's take a look at where the heat comes from and the thermal protection system that is supposed to protect against that heat.

Why does it get so hot on re-entry? Basically all the potential energy that it had at a height of 320 km gets converted into thermal energy. How much energy is that? About 6X10¹² J or 6 terajoules or approximately the amount of energy you would have used if you had left a 100-watt lightbulb on since the birth of Jesus.

(Note that if you did that calculation using the approximation mgh for potential energy, which is accurate only near Earth's surface, instead of Newton's Universal Law of Gravity, which is, of course, universal, you would be off by about 4.4%.)

That's a lot of energy, and it can raise an object's temperature very high - like the meteors that burn up in the atmosphere, only to be obscured from my vision by clouds (so sad). We don't want the shuttle to burn up in the atmosphere, so it is protected by a complicated system of insulators:

1) Felt reusable surface insulation (FRSI) is used in a few places that won't get very hot. FRSI only protects up to about 370^oC - that's not even glowing hot. Your furnace chimney might get that hot.

2) Low-temperature reusable surface insulation (white tiles) and advanced flexible reusable surface insulation (a "quilted blanket") are used to protect parts of the shuttle to a temperature of about 650^oC. At that temperature the surface would be just barely glowing red.


3) High-temperature reusable surface insulation and fibrous refractory composite insulation (black tiles) will protect up to about 1260 ^oC. Anything that hot glows a bright red, like an electric stove burner set on high. It is these inch-thick black tiles that have a 3 1/2 inch gouge in them (see photo). If the aluminum framework below the tiles were to reach a temperature of 1260^oC, the shuttle would be in trouble. The melting temperature of aluminum is only 660^oC!

4) Some parts of the shuttle take the full hit of re-entry and can get as hot as 1500^oC (approximately the melting temperature of iron). These parts are protected by reinforced carbon-carbon panels. I don't know the actual heat characteristics of this material, but carbon itself remains solid up to 3700^oC, at which point it sublimates.

Oh, and did you notice the printing on the tiles in the photo above? Those are individual tile ID's, painted in Sperex VHT (very high temperature) paint, developed for automobile manifolds. Sperex is only rated to 700^oC. Clearly since the paint remains from launch to launch on the black tiles, the paint must actually withstand temperatures more like 1260^oC. Sometimes you get more than you pay for!

8/18/07 Update
Apparently NASA has decided not to try to repair the damage to the thermal protection system. "(T)he surface of the gouged tile on Endeavour's belly will experience between 2,000 and 2,100 degrees Fahrenheit (1,093-1,148 degrees Celsius), with temperatures on the inner felt strip near the shuttle's aluminum skin reaching about 325 degrees Fahrenheit (162 degrees Celsius)."

So tests and simulations seem to indicate that the tile won't get any hotter than it can handle, and the felt won't get hotter than it can handle. However, some are still concerned that the adhesive holding the tiles on may get too hot and break down, releasing more tiles than was assumed when testing. If that happens, things could get hotter than the tests indicate. Let's hope NASA is right.

Also, it turns out that bad weather due to Hurricane Dean will force the shuttle to come back sooner than expected. No time for repairs, anyway.

Update Aug 22: In case you haven't heard, the space shuttle made it back safely yesterday. The experts made the right call.

Phunday, the Easy Way

Update: Didn't see any meteors. I blame the clouds. It wasn't totally cloudy when I went out - still could see some stars here and there, but it got to be pretty total cloud-cover by about 12:30, so I gave up. :( May try again tonight, if Weather Underground turns out to be wrong about the 68% cloud cover prediction.

I'm taking the easy way out for my phunday post, and just posting a link to Yahoo's "Top 10 Scientifically Inaccurate Movies." My favorite is "Independence Day." People are always forgetting about tidal forces.

Now I'm going to watch for Perseids!