Questions Show: Spiral Arms, Seismic Waves on the Sun, and our Favorite Gear

Artist illustration of the Milky Way

This week we explore galactic spiral arms, seismic quakes on the Sun, and our picks for astronomy gear. If you've got a question for the Astronomy Cast team, please email it in to info@astronomycast.com and we'll try to tackle it for a future show. Please include your location and a way to pronounce your name.

Spiral Arms, Seismic Waves on the Sun, and our Favorite Gear

Is there a traffic jam in spiral arms of galaxies?

• Abstract: Density Wave Theory of Galactic Spiral Arms (pdf)
• Density Wave Theory — Wiki
• Spiral Arms animation – Vanderbilt U

Why do seismic waves on the sun accelerate?

• Solar Flares Leave Sun Quaking — SOHO
• Movie of seismic waves on the sun – Stanford U
• Abstract:  Properties of Flares-Generated Seismic Waves on the sun – arXiv
• Mythbusters:  Helium and Sulfur Hexafloride — You Tube

What are Fraser's and Pamela's favorite astronomy gadgets?

• Fraser:  Green laser pointer
  
• comparison of different brands
• Please be careful when using a green laser pointer!!
• Pamela:  1. Binoculars (a guide from Astronomy.com)
  
• 2.  TelVue Pronto Telescope (a review)
• 3.  Ritchey-Chretien telescopes
• CCD – wiki
• Reviews of different "Go-To" telescopes

Why are the Pioneer spacecrafts slowing down?

• Pioneer anomaly – Planetary Society
• Pioneer Anomaly, a deviation from Einstein Gravity? — Universe Today
• Pioneer Collaboration — ISSI

How can astronomers tell the distance of an object from red- and blue-shifting of light?

• Doppler shift -- UCLA
• Cepheid Variable Stars and Distance Determination — Australia Telescope Outreach and Ed.
• Measuring distances to stars
• The Cosmic Distance Scale and Standard Candles — UTK
• Cosmic Distance Ladder -- Wiki
• Andromeda/Milky Way collision — Hayden Planetarium

Why are galaxies colliding if everything in the universe is moving away from everything else?

• Colliding Galaxies — UTK
• How can galaxies collide in an expanding universe? — Cornell U
• What happens when galaxies collide? — Cornell U

On how much of the sun is fusion taking place?

• Answer:  about 25%
• How the sun works — HowStuffWorks
• Convective zone – U of Michigan
• Radiative zone – U of Michgan

Why are globular clusters shaped the way they are?

• Globular Clusters — SEDS
• Globular Clusters:  The Middle Ages – Star Stryder
• Abstract: Three Body Interactions of Black Holes in Globular clusters

What is a parsec?

• Answer:  3.26 lightyears
• Parsec – World of Astronomy

Meet up with Pamela and Chris Lintott at Mabel's Tavern in London on Nov 23, 2008:  details

1. Charles Kuester Says:
   November 24th, 2008 at 8:25 pm

   Great show, as usual.

   When it comes to gadgets for astronomy I found a great one that I could build myself for next to nothing. An image stabilizer for binoculars. Anything more than 7 or 8x is almost impossible to hold steady and I have an old pair of 10×50's that I hardly ever used because of this. So when found this do-it yourself binocular stabilizer on the Sky & telescope website I built one. Find it here:

   http://www.skyandtelescope.com/howto/diy/Image-Stabilize-Your-Binoculars.html

   It's a little bulky and funny looking but It works great!

2. Stephen Says:
   November 26th, 2008 at 1:40 pm

   Uhm, did a clearer explanation of the twin's paradox get posted somewhere? In the old days, i was clear on this one, now i'm not.

3. Tom Leach Says:
   November 27th, 2008 at 8:46 am

   Did I hear correctly on your podcast that our Galaxy Milky Way is believed now to have only two arms? (the Orion Arm and the Saggitarius Arm?)

4. AJenbo Says:
   December 4th, 2008 at 1:45 am

   I keep getting an error when trying to listen to this show

5. Roger Says:
   December 4th, 2008 at 12:51 pm

   I'm keep getting file errors to =(

6. Stephen Says:
   December 9th, 2008 at 11:09 pm

   Pioneer anomaly. Last i heard, the Planetary Society funded a project to get the old tapes out, copy them to modern media, and start analysis. And, last i heard, about a third of the anomaly has been accounted for by thermal modeling of the space craft. No outgassing. The Pioneer anomaly is a very subtle effect, and would have been overwhelmed by anything so crude. There is simply more radiation going in one direction than another. Photons carry momentum.

   Gear. I like the new Newtonian Dobs with push-to computer locators. You get aperture per dollar like no other scope design can give you. Orion has a 10" version that fits in your car, sets up including 2 star alignment in under 3 minutes in the dark and the cold, hardly ever needs collimation, the finder scope clips on and still doesn't need alignment, and did i mention it's 10"? And it's $700.

   How could you possibly want a 76 mm doublet acromat for $1700 that still needs a mount? For $1600, you can get a Vixen 140 mm 4 element neo-acromat. It's cheaper and nearly twice the aperture! And in no case will your mount fit in carry on.

   And yet there is a 10" Newtonian dob that does fit in carry on. I'm not sure the Johnsonian is still made, however. And Sky & Tel ran an article about a home made 8" that fits in carry on. These scopes include the mount, in carry on.

   But i'm having lots of fun with my laser pointer. Outreach has never been so easy. I know a guy who uses his laser pointer as his finder. He's got it mount on the scope, and just moves the scope until the pointer is where the object is on the chart. I just got my scope mount and haven't had a chance to try it out.

7. AJenbo Says:
   December 12th, 2008 at 3:34 am

   I sent an email to the AstronomyCast Team and the episode is now fixed

8. Tymnenuntee Says:
   December 17th, 2008 at 6:28 am

   ???????? | ????????????? ??? ?? ????? ????? ? ?? http://p1p3.net ???? ?? ??? ?? ? ???????? ??????? ?

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