August 2009 - Utah-Astronomy - mailman.xmission.com

Re: [Utah-astronomy] Findings of the Review of US Human Space Flight Plans Committee
by Gary Vardon 29 Aug '09

29 Aug '09

I would argue that manned space flight is much more costly, risky and yields less scientific bang for the buck. This does not mean that I am against manned space flight merely that if funds are limited they should go to unmanned missions. Funds for manned missions should be in addition to the funds allocated for unmanned flights. If funds are lacking the manned missions should go. Sincerely, Gary Vardon The book DO It Right will help you understand vital ideas leading to your geater success. GO to PublishAmerica. -----Original Message----- From: Jay Eads Sent: Friday, August 14, 2009 2:05 PM To: utah-astronomy(a)mailman.xmission.com Subject: [Utah-astronomy] Findings of the Review of US Human Space Flight Plans Committee The Presidential committee led by Norman Augustine chairman of the Review of U.S. Human Space Flight Plans Committee gave their results this week http://spaceflightnow.com/news/n0908/12augustine/ in case anyone was interested. Here are some highlights and from it I took it to mean that the current plan is not feasible as funded so changes will be forth coming. Sally Ride a panel member and former astronaut explained that the "unconstrained budge" which would cost an estimated $50 billion means that Orion and Ares I arrive after a 2016 ISS deorbit (at a cost of 1.5 billion) since ISS is only funded through 2015. So the two rockets arrive but have no where to go. If NASA has to live wit the 2010 budget guidelines provided by the Obama administration the Ares 5 heavy lift rocket will not be ready until 2028. Here we have a heavy rocket designed to go to the moon and take material with it but nothing is deployed and no money to fund a lunar system. $3 billion was cut by the Office of Management and Budget from NASA's long-range budget projected last spring, money to be used for the development of the Ares V prior to the Augustine panel being formed. Knowing that a large budget would not pass the Office of Management and Budget right now, and a small budget would not forward exploration I guess they are trying for the just right size. So the proposal does this: 1. Ramps up slowly to $3 billion a year over the budget they've been given until 2020 when the budget follows inflation of 2.4% 2. Astronauts return to the moon in the 2025 timeframe 3. ISS as Russia, Japan, Canada and the ESA want, is left up through at least 2020. 4. IF ISS is left up then Ares I development is probably suspended fueling the money for booster development away from Ares I into the ISS operations (better go see the test on August 25!). 5. Augustine panel favors the development of commercial rockets and capsules to ferry astronauts to and from low-Earth orbit. 6. Augustine panel assessing the trade-off of flying 1 or 2 Space Shuttle Missions a year reducing the gap before the new rocket systems are developed. 7. I found this one perhaps intriguing: "the panel is assessing options for deep space exploration that might bypass the moon in favor of near-Earth asteroids, lunar reconnaissance flybys and even flybys of Mars, with "off ramps" for development of systems for use on the lunar surface and eventual manned landings on Mars." 8. Ares V rocket would be modified and made man rated to carry astronauts. No Ares I development with any of these cases though. Sally Ride's final comment was ""We kept coming up with a common theme, which is this budget is very, very, very hard to fit and still have an exploration program," Ride said. "In fact, we are still looking for an existence proof that we can actually find one. We haven't found one yet, but we're still looking." A few other items are listed, you can read the article. I am beginning to think that if I live to around 75 (2041) I may not live to see man leave low earth orbit. I wonder if we will get out of low earth orbit before the end of this century? I also wonder if emphasis is being placed on non-human exploration methods as they are less risky and can provide scientific breakthroughs with less cost? Or are they facing the same budget constraints as the human exploration side? I think of the comment I read lately by the director of the Mars Explorers. As successful as they have been they have done in 18 months what a man could have done in several weeks. Should we push back human explorations and put that money into other projects of exploration? Do you think you'll see human spaceflight beyond low- earth oribit in your lifetime? _______________________________________________ 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.slas.us/gallery2/main.php Visit the Wiki: http://www.utahastronomy.com

9 19

Aug 29 00:42AM to 2:46AM - Jovian Moon eclipse and occultation
by Canopus56 28 Aug '09

28 Aug '09

Aug 29 00:42AM to 2:46AM - Jovian Moon eclipse and occultation Although the weather is not cooperating, there is a Jovian eclipse and occulation after midnight tonight between Io (1) and Europa (2): 29 6:42 6:55 1o2 53% 29 7:38 7:46 1e2 28% - Clear Skies - Kurt ----------------------------- September 3 - Next week - another Jovian event - No moons Jupiter Without Moons by Tony Flanders -------------------------------------------------------------------------------- On the night of September 2-3, 2009, a remarkable celestial event will take place. From 4:43 to 6:29 Universal Time on the 3rd (which is 12:43 to 2:29 a.m. EDT on the 3rd, or 9:43 to 11:29 p.m PDT on the 2nd), a casual look at Jupiter through a telescope will show no moons at all. It's quite common for one of the four Galilean moons be hidden, and it's not rare to see only two moons. But only a few times in a century do all four moons hide simultaneously behind or in front of Jupiter. http://www.skyandtelescope.com/observing/highlights/52543517.html

1 0

NGC 7331 and friends
by Patrick Wiggins 28 Aug '09

28 Aug '09

When I finished with my photometry stuff last night the skies were too good to go to waste. So I looked about and found NGC-7331 and its retinue of smaller galaxies high in the sky. I got 30 one minute exposures and after some quick and dirty processing I came up with this: http://users.wirelessbeehive.com/~paw/temp/NGC7331.JPG Not Tyler-like (notice the cores are burnt out) but I don't have his patience or skill. :) Still I rather like it. BTW, I kept the originals and the master flat and master dark. I'd be happy to pass those on to anyone who'd like to experiment with them. Clear skies! patrick

4 5

Using photometry to find skybrightness above the LCROSS impact site and Brightness of Impact Cloud
by Canopus56 27 Aug '09

27 Aug '09

In the spring of 2009, the LCROSS Team issued a single frequency estimate at 550nm of the impact ejecta curtain brightness of approximately 3.0 mpsas during the first between 10 and 60 seconds after impact. Heldman (2009). A version of Heldman (2009) is reproduced as a low-resolution frame on the LCROSS Team Observation Campaign webpage (2009). url: http://lcross.arc.nasa.gov/impact.htm . For amateur CCD or video imaging purposes, this understates the likely mpsas, since CCD cameras respond to the broad integrated wavelengths between approximately 380nm and 1000nm. CCDs do not respond at a single wavelength. The LCROSS-EDUS impact will generate a dust ejecta curtain about 10 km x 5 km high between 40 to 60 seconds after impact according to the NASA-LCROSS Team conservative best estimate impact model (CBEIM). Bart(2008) at slides 19-20; Wooden (2008) at slide 2. This current conservative LCROSS CBEIM translates to a 3 arcsec x 2.5 arcsec ejecta dust cloud at a mean lunar distance of 384,400km. A larger hypothetical 20 x 20 km ejecta curtain converted to a circular shape of equal 400 sq km area has a diameter of about 12 km. As seen from Earth at a mean lunar distance of 384,400 km, the 20 x 20 km square billboard would be 11 x 11 square arcsecs, or equivalent to a circle with a diameter of 12 arcsecs. At those ejecta curtain sizes and an irradiance at a single wavelength of 550nm of 3.0 mpsas, the corresponding integrated magnitudes of the curtain would be 1 integrated magnitudes for the 10km x 5km scenario and -1.9 integrated magnitudes for a 20km x 20km, 12 arcsec diameter scenario. This apparent brightness (3.0 mpsas) provides a favorable contrast index against typical Earthshine (dark limb) irradiance between 12 to 17 mpsas for the dark limb (mean value 15.44 mpsas) but not against Moonshine (bright limb) at 4 to 6 mpsas. The LCROSS ejecta curtain will present a uniquely difficult extended object for amateurs to image. The impact is hoped to occur when a permanently shadowed region (PSR) is on or near the bright limb terminator with the crater surrounding the PSR being partially lit at a very low sun angle. The dust ejecta curtain will rise into the sunlight and reflect light back to Earth-based telescopes against the background darkness of the night sky immediately adjacent to the dark limb. At the moment of projected impact, 2009-10-09 11:30UT, the Moon will have the following geocentric empheris characteristics: Phase angle 65.2984 Perscent illumination 71% illumination Terminator colongitude 158 Lunar age 20.7 days The average sky brightness under moonlight scattered illlumination (expressed in mpsas) at various distances from the Moon was modelled with precision by Krisciunas and Schaefer (1991) based on earlier measurements by Krisciunas (1990) and an earlier rough model by Walker (1987). See Krisciunas (1990) at Figure 8, reproducing the rough model of Walker (1987). The effect of moonlight is additive. Under the rough Walker model, the full Moon adds about -1.9 mpsas to whatever your base sky brightness is. At a lunar age of 20 days, about -1 mpsas is added. If you are observing from a light-polluted 3 integrated magnitude urban sky (equivalent to about 16.9 mpsas), the light from a 20 day old Moon adds on average about -1 mpsas to your sky brightness. That is it would reduce a 16.9 mpsas sky to a 15.9 mpsas sky - equivalent to about 2.1 integrated magnitude sky. Conversely, if you travel to your favorite 21 mpsas - 6.1 integrated magnitude rural dark sky site, the same Moon reduces sky brightness to 20 mpsas or 5.5 integrated magnitudes. The effect of moonlight is dependent on the lunar phase and the degrees of distance between the Moon and the observed target. Krisciunas and Schaefer (1991) (at Table 2) give the following rough delta mpsas (as measured through a Johnson V standard filter) for the lunar phase angle and distance between the Moon and the observed target. These results are for their improved model over the Walker (1987) rough model: Phase angle Angular distance Moon-target 05 30 60 30 -4.5 -2.9 -2.2 60 -3.7 -2.1 -1.5 90 -2.7 -1.4 -0.9 120 -1.6 -0.6 -0.3 The value in Krisciunas and Schaefer's table closest to LCROSS impact circumstances is a phase angle of 60 and an angular distance of 5 degrees. They report a delta mpsas of -3.7 for those circumstances. (Lunar phase angle is the number of degrees between the Sun, the Moon and the observer. It varies between 0 and 180 degrees. It is the S-T-O angle reported by the NASA/JPL Horizon's Ephemeris system. Phase angles less than 90 degrees imply backscattering of light; phase angles greater than 90 degrees imply forward scattered light.) For an urban 16.9 mpsas (3.0 integrated magnitude) sky, 60 degree phase angle moon light would increase sky brightness near the Moon by -3.7 mpsas to about 13.2 mpsas - or -0.5 integrated magnitudes. At the rural dark sky site with an excellent 21 mpsas - a 6.1 integrated limiting magnitude - moonlight was reduce the limiting magnitude to 17.3 mpsas or a 3.3 integrated limiting magnitude. Equating (roughly and perhaps inapproriately) the LCROSS team's single 550nm wavelength mpas of 3.0 to the LCROSS ejecta curtain to the full Johnson V-band mpsas, indicates that the LCROSS ejecta curtaion might have a positive contrast index even in an urban light polluted environment: Sky brightness 5 degs from Moon Curtain MPSAS Contrast Index Urban 13.2 3.0 4.1 Rural 17.3 3.0 5.7 Even though the LCROSS ejecta curtain will be seen rising against a bright background sky, at an average curtain brightness of 3.0 mpsas, it still may be visible or subject to imaging. An obvious implication of the above is that travelling a dark sky site may improve the contrast between the ejecta curtain. Dark skies - even though they are washed out by moonlight - still relatively increase an amateur's likelihood of visually detecting the impact curtain and of imaging the curtain. An extended object fainter than 3.0 mpsas - such as Saturn - has been widely imaged as it was occulted by the Moon. Saturn has a computed mpsas of 6.7 based on an diameter of 14 to 20 arcsecs and an integrated magnitude ranging between 0.4 to 1.2 mags. But unlike Saturn, the LCROSS ejecta curtain will be a low-density dispered dust cloud. In an abbreviated literature search, no articles were found concerning the additive effect of moonlight between 0 degrees and 5 degrees from the lunar limb. Lunar amateurs and lunar occultation amatuers are familiar with this effect of moonlight. Only the brightest stars can be seen next to the bright limb of the full Moon. Magnitude 4 to 7 stars disappear within an arcminute of the bright lunar limb. Amateurs in the LCROSS Google observation group ( url: http://groups.google.com/group/lcross_observation ) have been attempting to gain some understanding of the brightness of the night sky above and within a quarter-degree of the lunar limb by observing grazes and imaging stars during lunar occulations of clusters. Example images are: Chris Kitting. Moon occulting Pleaides 2009-08-14 9;46UT http://01227941410742638900-a-g.googlegroups.com/web/CKitting_20090814_0946… http://tinyurl.com/oopegs Image details: http://groups.google.com/group/lcross_observation/msg/80c0f58084faec69 In Kitting's image, magnitude 7 to 8 stars in Merope's Tail are co-exposed close to an overexposed lunar terminator. Derek C. Breit April 25, 2007 6.6 mag star graze on dark limb http://www.poyntsource.com/tmp/April_25th_2007_Graze.mpg (24 mb mpg) These experiments have had limited success, principally because the few number of such occultation events and uncooperative weather limits the ability to gather useful data using those techniques. An alternative technique would be CCD photometry analysis. In this technique, the south pole of the Moon is imaged at high focal ratios (f/30 plus) at various exposure times from underexposure to high over-exposure. The camera and scope are then retargeted without changing focal length or exposure on an open cluster at a similar altitude as the Moon. The V magnitudes of open clusters are well-known and plots of clusters limited by a specific magnitude are easily made using the Webda's online database. url: http://www.univie.ac.at/webda/ The open cluster provides reference stars to determine simple transform coefficients for the CCD camera at a given exposure setting through standard B and V or C and V filters. Modern imaging processing packages like AIP4WIN include photometry utilities by which the differential magnitude of stars can be found and correlated to CCD well ADUs. See single star photometry in Exercise C.5 in the AIP4WIN handbook and the extractive photometry utility on the AIP4WIN menu (Measure | Photometry| Extractive Photometry). The open cluster image also provides an image scale that can be applied to your image of the south pole. This poster unsuccessfully attempted a preliminary test during the August 14, 2009 lunar occultation of Pleaides. An image of the south pole was taken, followed by an image of the Alcyone triple. Unfortunately, weather conditions and an unanticipated glare problem unquie to the Mak imaging scope prevented getting a useable result. The Meade ETX 125 Mak has a curved corrector plate. When slewing from the south pole to Alcyone, the Mak's curved surface diverted off-axis lunar glare into the tube and washed out the image. No useable photometry information could be gleaned from the image, but a demonstration information on image scale could be found. A panel summarizing this technique demonstration test can be seen at: http://members.csolutions.net/fisherka/astronote/observed/LCROSS/2009_8_14_… http://tinyurl.com/n4l8sn The next best - and last - analogous lunar south pole illumination to the LCROSS impact will occur on September 9 11:30UT: Lunar libration data for images and impact Source: LTVT ephemeris data, topocentric W111.8 N41.8 Date-TimeUT libr_lat lib_long colong illumfrac 20090907 1130 -6.2 -5.5 128 92 20090908 1130 -6.2 -5.5 140.2 85.5 20090909 1130 -6.1 -5.4 152.3 77.3 20091009 1130 -3.5 2.8 158.2 70.9 Impact day 20090910 1130 -5.4 -5.1 164.4 67.7 20090911 1130 -4.4 -4.3 176.5 57.1 20090912 1130 -3.2 -3.3 188.7 45.8 Date-TimeUT Lunar age (days) 20090907 1130 18.1 20090908 1130 19.1 20090909 1130 20.1 20091009 1130 20.6 Impact day 20090910 1130 21.1 20090911 1130 22.1 20090912 1130 23.1 On the early morning of Sept. 8, there are no appropriate open clusters near the Moon. NGC752 (Caldwell 28) is higher in the sky. The Double Cluster is also at a higher altitude, but visible. On the early morning of Sept. 9, the Moon and M45 will both be visible, but the Pleaides will be a higher altitude. On the morning of Sept. 10, the Moon will be near the Pleaides and at the same altitude. On the evening of the 11th, a number of open clusters might be used for baseline photometry - M45, M36, M37, M38 or NGC1647. As we approach full Moon on September 4, the Moon will be 68% illuminated on August 29 (from the opposite direction). The night of August 29 provides an opportunity to set up and test equipment under test analogous illumination before September 9. On the evening of August 29, the Moon will be low in the southern sky just below the apex of the Sag "teapot". Open clusters M21, M23 and M25 are also visible, but at higher altitudes. Amateur photometry to determine sky brightness within one quarter degree "above" the lunar south pole on September 8 through 11 (particularly on September 9) will help determine if the LCROSS impact ejecta cloud will have sufficient contrast against the moonlight night sky to be seen and imaged. Imaging through filter combinations (V-C, V-I, B-V) will give the most accurate results. To confirm whether the background sky brightness will not overwhelm the ejecta curtain brightness, better photometry data might be collected by amateurs within zero to 5 arcminutes "above" the south lunar pole. Clear Skies - Kurt Disclaimer: This is an amateur note. Criticisms and corrections to the above are welcomed. Fisher, Kurt A. (amateur). 2008. Conversion Calculator for NELM(V) to MPSAS (B) systems. (Web calculator). url: http://members.csolutions.net/fisherka/astronote/plan/tlmnelm/html/NELM2BCa… (last accessed 26 Aug. 2009) Heldman, J. (LCROSS Team). Email Feb. 11, 2009, Slide 4 (slide4.gif). Krisciunas, K. 1990. Further measurements of extinction and sky brightness on the island of Hawaii. PASP 102:1052-1063. Bib. Code 1990PASP..102.1052K url: http://adsabs.harvard.edu/abs/1990PASP..102.1052K (last accessed 26 Aug. 2009) Krisciunas, K. and Schaefer, B.E. 1991. A model of the brightness of moonlight. PASP 103:1033-1039, Bib. Code. 1991PASP..103.1033K url: http://adsabs.harvard.edu/abs/1991PASP..103.1033K (last accessed 26 Aug. 2009) LCROSS Team. 2009. Average and Edge Brightness of Ejecta Curtain (Figure). LCROSS Observation Campaign website. url: http://lcross.arc.nasa.gov/impact.htm and http://lcross.arc.nasa.gov/observation.htm Image: observation05.jpg (last accessed 26 Aug. 2009) Walker, A. 1987. ________________. NOMO Newsletter. 10:16.

1 0

Re: [Utah-astronomy] Jupiter eclipse
by Canopus56 27 Aug '09

27 Aug '09

> Any of you experts know how often something like this occurs, visible to us? I believe it is related to six year ecliptic latitude of Jupiter. These mutual phenomena of the Jovian satellites are more frequent as Jupiter crosses the ecliptic plane. See http://www.skyandtelescope.com/community/skyblog/observingblog/53840132.html "Right now the planet Jupiter is oriented such that its equator and the orbits of its four big moons are almost exactly edge-on to the Sun and Earth. This alignment happens every six years, on opposite sides of Jupiter's 12-year orbit around the Sun." - Kurt Table 1. Jupiter's Geocentric Ecliptic Latitude 1997 to 2027 Date Eclip Lat Min Year 1997-Aug-27 0.15 x 1998-Aug-27 2.52 1999-Aug-27 3.77 2000-Aug-26 3.55 2001-Aug-26 2.43 2002-Aug-26 0.94 2003-Aug-26 -0.58 x 2004-Aug-25 -1.92 2005-Aug-25 -2.9 2006-Aug-25 -3.35 2007-Aug-25 -3.06 2008-Aug-24 -1.76 2009-Aug-24 0.5 x 2010-Aug-24 2.78 2011-Aug-24 3.8 2012-Aug-23 3.43 2013-Aug-23 2.25 2014-Aug-23 0.75 2015-Aug-23 -0.75 x 2016-Aug-22 -2.05 2017-Aug-22 -2.99 2018-Aug-22 -3.37 2019-Aug-22 -2.95 2020-Aug-21 -1.49 2021-Aug-21 0.87 x 2022-Aug-21 3.02 2023-Aug-21 3.81 2024-Aug-20 3.31 2025-Aug-20 2.08 2026-Aug-20 0.58 x 2027-Aug-20 1.0798 Table 2. Jupiter's Geocentric Ecliptic Latitude at 30 day intervals during 2009 Date Eclip Lat 2009-Jan-01 -1.13 2009-Jan-31 -0.83 2009-Mar-02 -0.50 2009-Apr-01 -0.16 2009-May-01 0.16 2009-May-31 0.41 2009-Jun-30 0.56 2009-Jul-30 0.58 2009-Aug-29 0.48 2009-Sep-28 0.36 2009-Oct-28 0.30 2009-Nov-27 0.35 2009-Dec-27 0.52 Ob-lon Ob-lat = Apparent planetographic ("geodetic") longitude and latitude (IAU2000 model)of the center of the target disk seen by the observer at print-time. Light travel-time from target to observer is taken into account. Latitude is the angle between the equatorial plane and the line perpendicular to the reference ellipsoid of the body (e.g., reflects body oblateness). Positive longitude is to the west. For the gas giants Jupiter, Saturn, Uranus and Neptune, IAU2000 longitude is based on the "System III" prime meridian rotation angle of the magnetic field. By contrast, pole direction (thus latitude) is relative to the body dynamical equator. There can be an offset between the magnetic pole and the dynamical pole of rotation. Units: DEGREES

1 0

Jupiter eclipse
by Dale Wilson 27 Aug '09

27 Aug '09

Hi, Went over to spoc for the shin-dig, watching the double eclipse. What a fantastic view it was. Too bad nobody else showed up. I watched both shadows crawl accross the planet surface, then slowly the moons popped off the edge of the disk like a pimple. It's cool to see live action through a telescope. Dale

4 4

Fw: The Fallen Sky: KUER's RadioWest, 8/27/09
by Richard Tenney 26 Aug '09

26 Aug '09

Sounds like it might be interesting... --- On Wed, 8/26/09, Elaine Clark <eclark(a)kuer.org> wrote: > From: Elaine Clark <eclark(a)kuer.org> > Subject: The Fallen Sky: KUER's RadioWest, 8/27/09 > To: radiowest(a)lists.utah.edu > Date: Wednesday, August 26, 2009, 5:11 PM > RadioWest on KUER 90.1 > Thursday, August 27, 2009 > The Fallen Sky > > To say that Utah State English professor Christopher > Cokinos' new book is about > meteorites is to tell only part of the story. His 8-year > quest to learn about > space rocks and the people who have studied them took > Cokinos from Greenland to > Kansas to Antarctica. Along the way though, he says he > discovered new things > about himself and about home. Thursday, Christopher Cokinos > is with us to talk > about his book. It's called "The Fallen Sky: An Intimate > History of Shooting > Stars." > > Thursday, August 27th at 7:00 p.m., Christopher Cokinos > will give a reading at > The King's English Bookshop. For details, visit us on-line > at > kuer.org/radiowest > > ******** > > Get your RadioWest updates via Twitter. Follow us at > twitter.com/radiowest > > Join us for RadioWest weekdays at 11 a.m. Mountain on KUER > 90.1 and on XM > Public Radio Channel 133. You can also catch a rebroadcast > of the program at 7 > p.m. on KUER. Links to books and other resources related to > this topic are > available on-line at <http://kuer.org> This program will > also be available > on-line for 3 months following its broadcast. > > Please note: Program descriptions do not necessarily > reflect a complete or > final list of program guests. Due to the nature of live > programs, topics are > subject to change without notice. > > If you received this e-mail from another source and would > like to receive > RadioWest's program announcements, subscribe at > <https://www.lists.utah.edu/wws/subrequest/radiowest> >

1 0

Cosmos on Hulu
by Jay Eads 26 Aug '09

26 Aug '09

In case anyone doesn't own this it is on Hulu with a couple of commercials per episode. I figure they make good viewing for cloudy nights. Enjoy http://www.hulu.com/watch/63317/cosmos-the-shores-of-the-cosmic-ocean

2 1

Zhumell Tachyon 25x100
by Dale Hooper 24 Aug '09

24 Aug '09

I purchased the Zhumell Tachyon 25x100 binos from binoculars.com a couple months ago. I didn't feel comfortable recommending them until I had a real chance to check them out. I finally got my parallelogram completed and tried them out at Monte Cristo last week. They are certainly not apo's - but I think they work very well. Ron V. can also attest to how well they work. Anyway, I think they are a great deal and binoculars.com still has them in stock for $229 - including shipping. Here are a few of the features: - BAK-7 prisms - Accepts 1.25 inch threads - Waterproof and nitrogen purged - Includes case - 25 year warranty Clear skies, Dale.

1 1

Sunday night moonset
by Chuck Hards 24 Aug '09

24 Aug '09

Did anyone else happen to see last night's moonset? I was struck at how close to vertical the lunar crescent was oriented. Also the "large moon" illusion was very apparent, something I notice more often with a rising or setting moon closer to full phase. Beautiful sight.

3 2