April 2006 - Utah-Astronomy - mailman.xmission.com

RE: [Utah-astronomy] Can't quite figure this one
by Michael Carnes 13 Apr '06

13 Apr '06

Sorry to be away from the discussion. Had to take a work break. I'm glad we had a few other voices in this conversation. It's an interesting topic. I knew about the Terrestrial Planet Finder, but I thought it contained only an interferometer. The coronagraph was new to me. Looks like they're hedging their bets over at NASA. Pretty slick: they packaged two completely separate missions under one name and still managed to keep it alive. > >You might find these pages interesting. > >NASA Terresterial Planet Finder (TPF) Technology >Milestone Page >http://planetquest.jpl.nasa.gov/TPF/detectionMilestone.cfm > >NASA TPF Technology Plan (6.2 Mb) >http://planetquest.jpl.nasa.gov/TPF/TPF-CTechPlan.pdf > >TPF Homepage >http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm

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Re: [Utah-astronomy] Last night's lecture
by Michael Carnes 13 Apr '06

13 Apr '06

>Joe Bauman wrote: > >> Yeah, what about the giant brain bugs of Zorop 5? Surely they're more >> worthy of all the attention. -- Joe > >Shhh, we're no supposed to know about them... Everybody knows. Bush leaked it.

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Should this be reported? :) Very OT
by Patrick Wiggins 13 Apr '06

13 Apr '06

Someone told me about this earlier today. I'm guessing it's a mistake but have not decided if I should report it or not. Alternatively, we could just let Guy "handle" it... :) 1. Go to Google ( http://www.google.com/ ) 2. Type in the word "failure" (without the quotation marks) 3. Do not click on "Google Search". Instead click on "I'm feeling lucky". 4. Don't shoot me. I'm just the messenger... :)

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RE: [Utah-astronomy] Can't quite figure this one
by Michael Carnes 13 Apr '06

13 Apr '06

Hi Joe, There's nothing theoretically wrong with the idea, but in my day job I'm an engineer. It's in my DNA to pick at stuff until it either dies from the attention or stands up to the abuse. Everything you say is correct, but at the end of it all you have to have a telescope with enough resolution to pull a planet together (and you have to solve some giant stability problems). Otherwise it's just a diffused bit of light that may not even stand out from the background. That amount of resolution requires a huge objective--longer exposures don't make up for it. Someone who knows their Rayleigh would have to tell you just how big. Now that I've said all this, we'll find out that the Russians launched such a system for $273.

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Lend or sell a 2000 or 2001 Astronomical Almanac?
by Canopus56 13 Apr '06

13 Apr '06

If someone has a copy of the 2000 or 2001 Astronomical Alamanc that they could sell or lend me, I'd appreciate it. I would like to read the Moon position algorithm. Please bring to the next SLAS meeting or email me at canopus56(a)yahoo.com - Canopus56(Kurt) __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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RE: [Utah-astronomy] Can't quite figure this one
by Michael Carnes 13 Apr '06

13 Apr '06

Did a little quick math. Assume you wish to block a star the size of our sun at a distance of 10 light years. That star subtends an angle of approximately .0188 arcseconds. For every doubling of distance, that angle is halved. Assuming your block is a distance of 10 meters from your scope, it will require a diameter of .4555 microns. Of course that only works if your scope mirror is a point, since the occluding disk has an umbra and a penumbra. I don't know the distance required to make the shadow negigible, but thankfully the disk can get bigger as that distance increases. Of course, the difficulty of keeping that mechanical system in alignment is substantial. But let's assume you've cleared that technical hurdle. At the 10 lightyear distance, an earth-sized planet covers a whopping .000173 arcseconds. Pretty good scope, eh? I'm guessing you're still a lot better off with a great big interferometer and a good CCD system. You can throw away the bright data (the star) and focus your attention on whatever's left over. As I said before, interesting issue. Maybe the real optical guys can chime in on this. [Utah-astronomy] Can't quite figure this one > >It shouldn't matter that the blocking piece isn't a point. If covers >the star, you'd think it would then allow a view of the planet to >show up. Yet I don't think the star really would be a point -- but >why not? thanks, Joe

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Too much Gravity- Bad for your Health?
by astrodeb＠charter.net 13 Apr '06

13 Apr '06

Anybody see this? Too much gravity seems to be bad for your health. Kind of like a bad hangover. http://www.msnbc.msn.com/id/12300569/ Deb

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Re: [Utah-astronomy] Can't quite figure this one
by Michael Carnes 13 Apr '06

13 Apr '06

Hi Joe, Interesting questions. The real optical guys on the list will have me for lunch, but it would seem to me that building an occluding mask for such a situation might be a real trick. The success of a mask actually depends on a star being more than a point source. If a mask is only a point--besides the geometric impossibility of fabricating it--then it wouldn't really block any light at all. The mask would then have to be the exact diameter neccessary to block the disk of the star. While not a point, it would be pretty darned small. If it's too small, starlight would get past it and wash out a planet. If it's too large, it might occlude the planet as well as the star. If you got past that, there are still a great many issues concerning the resolving power of the scope. It would either have to be very large or would have to be a fleet of spaced scopes doing interferometry. I believe there's a NASA proposal for just such a project, minus the occluding mask. Given NASA's current infatuation with sending people to Mars, who knows when we get back to science... --MC -----Original Message----- >From: Joe Bauman <bau(a)desnews.com> >Sent: Apr 13, 2006 1:03 PM >To: Utah Astronomy <utah-astronomy(a)mailman.xmission.com> >Subject: [Utah-astronomy] Can't quite figure this one > >I have an optics question. A recent article mentioned how hard it >would be to detect the tiny speck of light emitted by an exoplanet, >because of the overwhelming brightness of the parent star. Fair >enough. However, if a telescope in space were to use a tiny device to >block the star's light, you'd think that would allow a view of the >planet. -- I'm sure that's not right. But why isn't it? In space, >isn't a star basically a point source? I would exepct no light >scattering in what is essentially a vacuum. So what's wrong with that >idea? Thanks, Joe > >_______________________________________________ >Utah-Astronomy mailing list >Utah-Astronomy(a)mailman.xmission.com >http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy >Visit the Photo Gallery: http://www.utahastronomy.com

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SLAS activities and changes in the weather cycle
by Canopus56 12 Apr '06

12 Apr '06

Major construction of the SPOC buildings occurred during 2000-2004, a period of relative drought in Utah: Utah rainfall during March, April, May and June 1948-2006 Mo/Yrs 48-05 00-04 05 06 March 1.8 1.3 2.4 2.7 April 2.1 1.9 3.2 May 1.7 1.0 2.9 June 1.0 0.8 1.7 4mos 1.6 1.3 2.5 Source: http://www.ncdc.noaa.gov/oa/climate/research/cag3/z4.html The last building, the refractor house was constructed in 2005. The Great Salt Lake level reflects these precipitation cycles: http://www.ncdc.noaa.gov/img/climate/research/2003/feb/gsl.jpg Precipitation can be used as an estimator of cloudy days per month. Average clear and cloudy days in Utah Mar Apr May Jun Mean Clear Days 7 7 9 14 Mean Partly Cldy Days 8 9 10 10 Mean Cldy Days 16 14 12 6 In 2005 - and now in the spring of 2006 - it looks like the weather cycle has changed. The first few months of the the observing season are wetter. Should the club adjust its activities during the early part of the observing season in response to this weather change? - Canopus56 __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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SLAS and Clark P websites and child safe internet content filtering
by Canopus56 11 Apr '06

11 Apr '06

Hope the following is of interest and help. I recently went through the process of registering a personal astronomy website through free internet content rating services in order to assure that the site could be seen by persons accessing from "child-safe" filtered websites. Not currently having any school age children, I have not tested the filtering from a Utah primary or secondary school computer. www.slas.us and Clark Planetarium do not appear to be registered with any of the child safe service sites. Since one current emphasis of SLAS's annual programs is to increase its Utah school activities, the following are my notes on registering a site for child-safe content filtering: 1) Utah Education Network - covers primary and secondary Utah schools - UEN Filtering Page Appears to use, through the Utah State Library, sites approved for primary and secondary schools through a private service branded "N2H2" (now also branded "SmartFilterWhere") run by Secure Computing Corp.: http://www.uen.org/policy/filtering.shtml Secure Computing Corp. N2H2 site checking utility - http://database.n2h2.com/cgi-perl/catrpt.pl Neither SLAS or Clark are returned by the checking utility as registered. If your site is not currently in the SmartFilterWhere-N2H2 database, the N2H2 site checker provides the option to suggest the site for inclusion in the N2H2 database. The UEN Help Desk may be able to provide advice. http://www.uen.org/utahlink/tours/tourViewCategory.cgi?category_id=20140&to… 2) Internet Content Rating Association (ICRA) http://www.icra.org/ ICRA site tester http://www.icra.org/label/tester/ The ICRA is one of two generally recommended child-safe filter services recommended by Microsoft at its Internet Explorer 6.0 site: http://www.microsoft.com/windows/ie/using/howto/security/contentadv/config.… ICRA is also used by Netscape Navigator, Netwatch feature. http://wp.netscape.com/comprod/products/communicator/netwatch/ The ICRA is a little complicated to use. After registering your site, they email you a content metatag that you have to put into the header section of _each_ web page of your website. http://www.icra.org/label/ Neither SLAS or Clark are returned by the checking utility as being labelled. 3) SafeSurf Corp. http://www.safesurf.com/ SafeSurf is the second of two generally recommended child-safe filter services recommended by Microsoft at its Internet Explorer 6.0 site. SafeSurf is also used by Netscape Navigator's Netwatch feature. SafeSurf is easier to register with than ICRA. Safesurf allows you to put in an entire domain subdirectory. Any webpage in that domain subdirectory is given the same rating. Note if you choose the option to self-rate your site as "Medical/Technical Educational Reference," your site will be restricted only the "older teen category." This will filter-out most school age children. Unfortunately, I could not find a site checking utility at the SafeSurf site. 4) PICS Standard - W3 Open Standard http://www.w3.org/PICS/ PICS uses a self-generated meta-data label - similar to ICRA - but there is no independent controlling service. PICS standard is referenced by Netscape Navigator and MS IE for content filtering. I found a PICS rating label generator on the internet at the Vancouver Webpages Rating Service: http://vancouver-webpages.com/VWP1.0/ Vancouver Webpages Rating Service PICS label generator http://vancouver-webpages.com/VWP1.0/VWP1.0.gen.html However, SafeSurf generates a third-party verified PICS level 1.1 label, so I decided not to add a second self-generated PICs label. The source HTML for the SLAS and Clark websites do not appear to contain any PICS labels. - Canopus56 __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

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