Strong evidence for albedo changes on the surface of Pluto - by reconstructing 1930s photometry

Yet another unusual paper by Louisiana State Univ. astronomer Brad Schaefer et al.: "We are reporting on a new accurate photographic light curve of Pluto for 1933-1934 when the heliocentric distance was 40 AU. [...] We find that the average B-band mean opposition magnitude of Pluto in 1933-1934 was 15.73±0.01, and we see a roughly sinusoidal modulation on the rotational period (6.38 days) with a peak-to-peak amplitude of 0.11±0.03 mag. With this, we show that Pluto darkened by 5% from 1933-1934 to 1953-1955." In contrast to a known darkening from 1954 onwards this effect cannot be due to our changing viewing geometry: "Thus, we now have strong evidence for albedo changes on the surface of Pluto, and these are most easily explained by the systematic sublimation of frosts from the sunward pole that led to a drop in the mean surface albedo."

In other news current images still show the storm on Saturn of which also a more recent Cassini image (from April 23) has been published. • Comet C/2005 L3 (McNaught) is a bit brighter than expected. • Even from a perfect spot there weren't too many Eta Aquarids visible. • Mira's strange tail is also emmitting in neutral hydrogen. • A more and more complete picture of the famous March 19 GRB is forming.

• First there was a cryptic NASA announcement about "the discovery of an object in our Galaxy astronomers have been hunting for more than 50 years", followed by rampant speculation everywhere - now we know what it was, namely the youngest known galactic SNR. And more than a few are angry about the hype fueled by NASA. Especially since the paper was out since March 10th ...

Ultimate groundbased map of Mercury created - by painting!

Even when it is as well placed in the sky as now, the planet Mercury is a very tough object for telescopes, and detail is hard to discern from noise. Image processing often needs to be extreme, everyone - professionals and amateurs alike - uses a different approach, and the usual computer-based methods for generating total maps don't work too well. Germany's most daring amateur astronomer has now tried a very different way of merging Mercury pictures: by re-painting them and adding the drawings! The result is a unique total map (shown above based on images by four amateurs and below with images from professionals added) - with MESSENGER soon completing the map of Mercury at high resolution, this will be the last ever such effort. But one that really works, as the new images coming from the current evening apparition do fit in. This was but one exciting result presented at the 27th Planeten- und Kometentagung in Violau, Germany, last weekend - here are some more:

• There is now a Venus Ground-Based image Active Archive where observers (mainly advanced amateurs; few pros contribute) can upload scientifically useful Venus images - which scientists from the Venus Express mission are eager to use in order to see the global context of their data.
  
  
• Amateur astronomers are using ever more exotic wavelengths to bring out unknown detail in planets with thick atmospheres - e.g. the methane band around 890 nm on Saturn and Jupiter or 1 µm on Venus where one can actually see the surface.
  
  
• The best mutual event of Uranus' moons during the 2007/8 equatorial plane crossing has been observed with a mobile observatory in Italy.
  
  
• Numerous images of Holmes were shown, in various stages of processing to bring out strange structure in the dust coma - what's going on physically here is less clear, though.(And the conference organizers, including this blogger, couldn't find one professional German astronomer willing to speculate on the comet's outburst in public ...)
  
  
• A Small Budget Sky Survey has been launched to coordinate small search programs for all kinds of celestial objects.
  
  
• A small minor planet occulted a bright star recently, and although only one observer was lucky to catch a (2 second!) drop-out, the high S/N of the data allowed for a lot of analysis.
  
  
• A professor for movie and TV sciences managed to image the phase of Venus without any refraction or reflection: He used a Fresnel zone plate telescope, 4 meters long, which he actually carried into the lecture hall.

In other news the daytime occultation of Mars by the Moon could be observed well during the planetary conference discussed above and in many other places - using polarizing, red and other filters helped a lot to bring the sky brightness down. • There are now naked-eye observations of comet Boattini which is being described as easy from the S hemisphere, with a rising light curve. • The true orbit of comet Beshore turns out to be very different and keeping it much fainter. • Another comet McNaught seems to be of similarly modest interest. • There are also a New Mexican fireball video, • a full report on the lunar crescent record sighting at 5 minutes from new, regardless of definitions, and • still fragments of USA 193 in orbit, despite the claim that they would all come down swiftly. • And finally Microsoft has released an early version of its World Wide Telescope which is causing lots of commentary, such as here and here and here and here and here and here and here and here and ...

New comet Beshore could reach 8th mag. - in the deep South

So far the observed arc of C/2008 J2 (Beshore) measures only one day: If the calculated orbit holds, the comet should reach 8-9 mag. in October. At a declination of -52°. Currently it is not a big light, in contrast to C/2007 W1 (Boattini) which has brightened quite a bit.

In other news there seem to be not two but several storms on Saturn, forming a complicated pattern in the STrZ, as monitored by R. Vandebergh. • One day after the conjunction the lunar crescent had grown a lot. • An impressive halo show from Finland.

• A preview of the daylight Mars occultation by the Moon on May 10 (which also happens to be Astronomy Day, which used to be mainly a U.S. event but is catching on internationally). • And debating the relative 'merits' of Armageddon & Deep Impact ...

Ten years later, impact movies have grossed 900 million bucks

It was ten years ago today when the motion picture "Deep Impact" had its premiere, followed by the similar "Armageddon" on July 1st. Both movies (eclipsing any others with an impact theme such as "Meteor" with its meagre $8.4m gross) have since grossed a total of 903,2 million dollars worldwide, according to the IMDB All Time list: Armageddon is on rank 44 with $554.6m, Deep Impact on rank 132 with $348.6m. (The BOM figures are very similiar.)

900 million dollars: makes one wonder how far the hunt for Near Earth Objects might have progressed today, had that doe (or a "stupid impact movie tax" :-) been spent on more search programs - NASA e.g., a major source of funding, currently invests just 4.1 million bucks annually! Now Canada seems to be willing to go ahead with the - similarly cheap - NEOSSat satellite mission for NEO hunting inside Earth's orbit which has stirred up some controversy (see also here, here and here). At NASA meanwhile, some dream about a manned NEO mission with the Orion capsule.

In other news the pairing of the young lunar crescent on May 6 with planet Mercury at dusk was quite a sight: collections from Germany - more and more pictures - and from around the world. • Images of asteroid Iris passing by the Sombrero galaxy. • It was 25 years ago that comet IRAS-Araki-Alcock was discovered and came very close to Earth. • Don Machholz has now been hunting comets for 400 months, since 1975. • How to date old sky pics with the help of stellar proper motions. • And thoughts on the huge solar flare of 1859, still the record-holder by far.

Ultimate lunar crescent record: Moon imaged five minutes before new!

He's the specialist for imaging the lunar crescent close to the Sun in full daylight (something possible only with violent electronic image processing) - and today Martin Elsässer has broken his previous record of last June: On Europe's best day of the whole year for this feat he got the Moon five minutes before new. And if there hadn't been a "Schweinewolke" at the wrong moment, the first-ever image of the crescent at the very moment of new moon would have been no problem, too. While no lunar elongation record was set today, the proximity in time to new moon is one.

Extreme crescent sightings are of considerable cultural interest, both for calendrical and religious reasons, have been the subject of many science papers, and even today this "astronomy sport" remains popular - though purists would probably only count visual sightings, with or even without optical help. As Mohammad Odeh from the ICO Project told this blogger last December, "[f]rom the big archive we have, we found that the least elongation for observed crescent by optical aid is 6.4 degrees."

In other news there are new orbital elements for comet 2008 J1 (Boattini) that improve visibility, but only a bit: In late summer it will be pretty close to the celestial North pole but perhaps not brighter than 13th mag. • And here are one and more pictures of Mercury & the Plejades on Apr. 4 (and earlier). The visibility is now approaching its peak, and the blogger has found out yesterday that the planet was seen easiest when the solar depression is around 9°. But that should change as it dims every day.

Sun does "not cooperate" in helping activity forecasts

It's been a good year since the Space Weather Prediction Center of the National Oceanic and Atmospheric Administration (of the U.S. but the global authority on the 'fluids' of this planet) released a 'consensus' on the next solar activity maximum. Because clear 'precursors' of the new cycle were lacking a year ago, the consensus among dozens of experts on solar behavior actually consisted of two competing predictions, and since then the progression of solar activity has been monitored. So what's the status after one year, this blogger asked, in the light of 'worries' among seasond solar observers at the 32rd SONNE-Tagung this weekend that the current minimum is felt to last longer than any in decades.

Replies NOAA's Doug Biesecker: "We 'released' the update [of the progression] today [May 2nd], which is, still no change. The questions that we set down one year ago to challenge either side [i.e. the competing modellers] have not yet been resolved. Mostly, the Sun is managing to not cooperate and lean one way or another. As for the minimum, it isn't all that unusual. Note, the last 2-3 minima were a bit higher than typical and I believe this one slightly below average, which makes it seem that much lower." Incidentally a 3rd (small) sunspot from the 24th cycle just appeared - and yesterday many nice prominences have been observed. So stay tuned: According to both the 'low' and the 'high' prediction, solar activity will begin to surge later this year and rise steeply throughout 2009. And by then we will also be able to better predict the shape of the 24th maximum.

In other news another comet Boattini has been discovered but won't get as bright as the more famous one, though here and there clear images were taken. • Currently asteroid (7) Iris is approaching Messier 104, the Sombrero Galaxy: a nice target for photographers. • Some more pictures of Mercury at the Plejades on May 2 (a rare view; now the evening apparition has grown to almost one hour per evening in the N hemisphere). • Saturn animated with the bright storm and many moons and in methane absorption at 890 nm with the planet much fainter than the rings. • Star gazing in Argentina at the Complejo Astronomico El Leoncito. • And hail to the Solar System Visualizer tool.

Some action in May: Moon vs. Mars & Phoenix vs. Mars

The current highlight in Earth's skies is the evening apparition of Mercury, of course, with the planet currently close to the Plejades low in the Western sky as shown in images from May 1+2 and May 2; on May 6 the young Moon will be near. Other space spectaculars include

• on the morning of May 5 the Eta Aquarids (the more South you are the better),
  
  
• on May 10 a daylight occultation of Mars by the Moon (e.g. in Germany), and
  
  
• on May 26 (UTC) the landing of Phoenix on Mars in its arctic region.

In other news here are the sky track of comet Boattini (now around 7.5 mag.), • an "anaphoric clock" or star disk in Kansas and • another attempt to save the night skies from light pollution, this time in California's Anza-Borrego State Park, which is even causing some interest outside the area. • And here are some cool sunset optical phenomena from Paranal.

Polar coronal jets of the Sun - imaged in stereo by STEREO

These are the most spectacular images published in a scientific paper from the STEREO mission: the hi-res pictures (on pages 10 and 13 of this PDF version!) show polar coronal jets from viewpoints 11° apart. The stereo view reveals "the 3D dynamics and morphology of a well-defined EUV coronal jet for the first time. Triangulations of the jet's location in simultaneous image pairs led to the true 3D position and thereby its kinematics. [...] Helical structure is the most important geometrical feature of the jet which shows evidence of untwisting. The jet structure appears strikingly different from each of the two STEREO viewpoints: face-on in the one viewpoint and edge-on in the other. [...] The clear demonstration of twisted structure in polar jets compares favorably with synthetic images from a recent MHD simulation of jets invoking magnetic untwisting as their driving mechanism." And this isn't even the first science result making use of the unique stereo vision of the STEREO mission.

In other news here are Mercury on April 29th, old Cassini views of the Saturn storm that has been active since last November (and now been joined by another storm NASA fails to mention), ionospheric data fed into Google Earth and a scientific paper on the Galaxy Zoo project. "The project has obtained more than 40,000,000 individual classifications made by ~100,000 participants," the authors marvel: "We find that Galaxy Zoo results are consistent with those for subsets of SDSS galaxies classified by professional astronomers, thus demonstrating that our data provides a robust morphological catalogue."

Now two bright storms on Saturn

Recent observations show that the long-lived storm on Saturn has been joined by a second one. Both look spot-like in small telescopes but in reality are continent-sized convection phenomena.

In other news an Apollo asteroid with a comet-like orbit but no cometary activity has been discovered. • The brightness of Nova Sgr 2008 is already way down again, at 8-9 mag. yesterday. • Details on how NASA s/c image the Earth at night with all its light.

• And in the Apophis affair the author of the article that started it all has told this blog that the student was explicitly happy with its content - thus recent attempts to blame it all on the stupid media don't fly. Meanwhile the science fair organizers refuse to release the student's original paper, citing copyright issues ...

Holmes 6 months into the outburst: still there, still pics, still news ...

It was the night of Oct. 23, 2007 (UTC) when something - still largely unexplained, it seems from the lack of substantial papers - dramatic happened to comet 17P/Holmes. Six months later the comet is exceedingly hard to see visually, though photographers can still be lucky. And in May the comet will come close to several open star clusters in Auriga: perfect opportunities for some fare-well shots! And then there is the suspicion of a 45-day periodicity of (minor) outburts: Yesterday's TA EC #2442 reminds us that "[t]hree such 'mini-outbursts' have occurred so far and, if strictly periodic, the fourth one is expected around April 25. Observers equipped with telescopes of 0.25-m aperture or larger plus CCD camera are strongly encouraged to monitor this object [Holmes' near-nucleus region] which is now quite faint - around 17th magnitude in brightness. [...] Take a series of images over a period of 30-60 minutes as soon as the sky is suitably dark after sunset, and whilst the comet is fairly high in the sky." • For an easier target, meanwhile, try C/2007 W1 (Boattini), now at 7½ mag.

In other news Mercury is now in the evening sky, easier every day. Here are also the ongoing Saturn storm on Apr. 23, Jupiter in methane with a small scope, notes about Nova Sgr 2008's brightening and a paper on detailled monitoring of Polaris which reveals "an increase in the amplitude by about 30% from 2003-2006" in this classical Cepheid. • Mecca (where some now want the zero meridian to be moved ...) is among the most light-polluted spots on the whole planet - while Kielder Obs. claims to have the darkest skies in the U.K.

• How about Cygnus w/o stars, only nebulae? • Or a "flight" to the Virgo cluster? • What using the VLT(I) feels like. • Why "selling" stars is bad, period. • And now you can determine the number of civilizations in the galaxy all for yourself: by entering the right numbers into the Drake Formula ...

Nova erupts in Sagittarius, now risen to 6.5 mag!

To celebrate the 100th post of this blog - in 3 months - a nova has erupted in Sgr: at first it had 8.4 mag. but has since risen in brightness, to 6.5 mag. some 24 hours ago (as reported in IAUC # 8937). • Nova Cyg 2008 #2 is much fainter. • A huge prominence on the Sun was filmed by STEREO on April 9.

In other news the bright storm on Saturn has become more obvious again and can be imaged with even small telescopes. • The good evening apparition of Mercury is about to begin. • Comet Holmes is now in eruption for 1/2 year! While Boattini could get interesting as well. • Detailed star maps can be downloaded for free. • Be careful with green lasers - they might be banned in Oz! • High-res images of the Earth are now being delivered from Genesis II. • More weird astronomy will be coming to TV.

• And in the bizarre Apophis affair there is now an attempt (note: this interview released by a school plays not well under IE, o.k. under Firefox) to blame it on the media. Unfortunately the organizers of the science contest that started it all refuse to release the actual 'paper' by the student to the media or disclose who the referees were, so it's hard to tell for sure how wrong it really was ...