Saturday, September 27, 2008

"Dwarf planet" to be replaced by nicer word?

While there are no indications that the new order of the solar system agreed on two years ago - with (8) planets, dwarf planets and small stuff - might be revised again, the IAU Division III "Planetary Systems Sciences" is working on some possible clarifications of the 2006 resolutions. They don't make any noise about their deliberations, but the latest IAU Information Bulletin carries an interesting note on the bottom of page 60 (PDF page 68): Among its "issues of concern" as of this April the Division lists the "[f]ormation of Task Groups to assess the hydrostatic equilibrium and clearing out of orbital zones for dwarf planets. Seeking advice from the EC about what we need to achieve by Rio. Finding another term for dwarf planet." The acronym "EC" means the IAU Executive Committee, and "by Rio" refers to the next General Assemby in August 2009 - when new resolutions could be voted on ...

In other news a meteoroid has grazed the upper atmosphere on Sep. 22 and vanished into interplanetary space again! This conclusion is based on just one video of the associated meteor and clever math. • Comet 205P/Giacobini with fragments a and b on Sep. 21. • The eclipse comet of 2008 in close-up and motion. This blog has learned, by the way, that there was yet another airplane going after the eclipse, this time from California - one of the Google founders had his plane going there, taking an astronomer with him (who can be seen in this picture sharing his eclipse video; no other details are known). Also more ground-based images taken right next to yours truly. And a Hinode X-ray image of the Feb. 7 eclipse, seen only as a partial one from orbit.

• The ISS & ATV imaged recently in high resolution - the latter will reenter on Sep. 29, and a major campaign is underway to observe the reentry from two airplanes. One of which is not an "Ames research aircraft", actually, but one of the Google planes mentioned above, a Gulfstream V full of portable astronomy equipment. ESA will blog about ATV's final hours. • And finally a paper on "SN 1987A's Wild Cousin" supernova 1996cr is making news now as "one of the nearest-known exploding stars of the last quarter-century" was nailed down with the help of lots of online archives. It's still 12 million light years away, though.

Thursday, September 25, 2008

Major planet science congress featuring amateur astronomers

Double progress for Europe's planetary science community: not only has the - still ongoing - 3rd European Planetary Science Congress exceeded both predecessors in global 'impact' and become, with 400 participants, a formidable addition to the annual planet conferences of the world. It is also unique in acknowledging the valuable role of amateur astronomers in this field of space science too (which, until just a few years ago, even most amateur planet observers hadn't realized): In 2007 there was a single poster (but it was well received and even came with a press release), this year the amateurs got a full oral session - and in 2009 there may even be a little extra conference tacked to the EPSC. Two of the contributions by German observers had already been presented in Violau earlier this year (though Gährken has now found out that already Pellier in 2004 clearly did detect Venus' surface); here's the new stuff from around Europe and the U.S.:
  • Pro planetologist R. Lorenz called for photometry and spectroscopy of Titan to nail down the reason for its brightness changes. Hubble and Keck give some clues at high angular resolution, but frequent photometry with small telescopes would provide important links, continuing Lockwood's longterm lightcurve.

  • S. Kowollik has found some correlation between amateur images storm activity on Saturn in 2008 and (so far unpublished) radio bursts detected by Cassini if the spacecraft was close to the planet. A quantitative analysis was hampered by the unwillingness of most photographers to supply unprocessed raw images if they had kept the data at all.

  • Observers from France and the U.K. outlined the quality of atmospheric feature drift measurements on Jupiter that modern imaging and semi-automatic analysis techniques have enabled; about 5 years ago electronic imaging at high frame rate with proper postprocessing finally began to exceed what the eye could discern in the best moments of seeing. Predictions based on amateur data of where a specific storm would be on Jupiter when New Horizons came by were even used by the project to accurately point the LORRI camera.

  • There was also a call to observe mutual phenomena of the Jupiter and Saturn satellites as both planets go through their rare equinoxes in 2009 - since esp. the Galilean satellites are very bright, even amateur equipment requires special techniques (read: defocus!) to deal with their blazing disks. Good lightcurves enable the measurement of extremely subtle orbital effects that cannot be seen in usual astrometry.

  • And space scientist/amateur astronomer D. Koschny reminded everyone of six basic rules every amateur must follow to produce valuable data: understand your equipment (e.g. timing issues), calibrate measurements, have a goal in mind (field, depth & resolution can't be had all at the same time), use standard reduction procedures, document all steps and publish and archive properly.
In contrast to occultation observers (who have IOTA), asteroid people (MPC), meteor fans (IMO) and variable star observers (AAVSO), planetary imagers have a problem, though: There is no science-grade archive site for their results. Only for Venus such a depository exists but not for the other planets - which tend to end up on picture-rich but scientifically less useful websites. Might the Integrated and Distributed Information Service (IDIS) - under development at node 7 of the same EuroPlaNet organization which also runs the EPSCs - be the answer (which will evolve into a "European Virtual Planetary Observatory")? Spacecraft, professional and amateur groundbased images and other data could find a common home here, just as pros and ams shared a lecture room yesterday: According to a poll, 13 in the audience regarded themselves as professionals, 10 as amateurs and 8 (including, interestingly, the chief scientist of the Huygens Titan capsule) as somewhere inbetween ...

Comet found - finally! - in special picture of 1 August total solar eclipse

It's extremely rare that a comet close to the Sun is spotted during a total eclipse of the Sun - it happened in 1882, when the comet was indeed close to the Sun (as a Kreutz Sungrazer), and in 1948. And in 2008: The SOHO spacecraft had already discovered and tracked the - this time pretty faint - comet, and observers of the eclipse were alerted the day before (if they still got e-mail whereever they were). Searches for this comet in even the best wide-angle images of the eclipse have been in vain, however - until now: in the spectacular wide-field composite already mentioned not only a lot of stars are visible but the comet has been identified! Looking just like a star, but the community is celebrating.

In other comet news comet 205P/Giacobini - recently recovered after 111 years and 16 perihelia in which it was not seen - has actually broken into at least 3 parts: The breakup may actually be the cause of the recovery because it increased the comet's brightness significantly. Here are an image of a fragment and animations; smaller optics don't show the smaller fragments. • Also a wide-field view of comet Lulin.

In news on other topics fireballs over the British Isles have been sighted. • The old nova GK Per is in outburst, having risen to 12 from the normal 13 mag. • And the small cycle 24 sunspot group, perhaps celebrated prematurely, is already gone again. While the Ulysses spacecraft is actually doing better than reported!

Tuesday, September 23, 2008

QUICK UPDATE: Solar wind 20-25% "less hard" now than during previous solar minimum

A NASA telecon is still ongoing in which Ulysses measurements are being discussed which show a marked change in the state of the solar wind between the last minimum of solar activity in the mid-1990's and now: The electron density is down 20%, the electron density 30% and the dynamic pressure of the solar wind - which determines the extent of the heliosphere - 20 to 25%. At the same time the solar corona doesn't look unusual. Apparently there are solar cycles much longer than the 11-year one at work: The solar wind is now "less hard" than at any time when in-situ measurements began in the 1960's.

Perhaps the upcoming minimum of the longer Gleisberg cycle plays a role - but there is no indication of another Maunder Minimum on the horizon. The new sunspot that appeared yesterday and is now developping was actually quoted at the telecon as evidence that the new cycle will soon take off. What the lower solar wind pressure means for near-Earth effects is not clear either: In general more (hard) cosmic rays from outside the heliosphere can enter now, and the Earths thermosphere is cooling - meaning that space debris has longer life times in orbit.

How long the solar minimum will last: what statistics say

Solar observers are celebrating a small sunspot from the new cycle that has just appeared - after so many months of low activity even this minute visitor is welcome. But is the current solar minimum really longer than any in recent memory? Indeed it is, an important analysis by Peter Meadows in The Astronomer (45 [Aug. 2008] 99-100) recently showed, but there have been much longer minima in the past centuries. He defines the length of the minimum as the interval when the 13-month average of the international sunspot number falls below 20: These periods have ranged from just one year in 1965 to 8 years in the early 19th century.

The smoothed number fell below 20 in January 2006, and thus the current minimum will last at least 2.5 and perhaps 3.5 years. In any case it is the longest since the one from 1931-35, confirming the suspicions of an unusually long one - on the timescale of a human life, that is. Meadows also finds a moderate correlation between minimum duration and the height of the next peak: expect a moderate one with a maximum smoothed number of 110 to 120. According to Ulysses data, by the way, the solar wind is at a 50-year low: NASA will hold a telecon about that finding later today.

In other news here is an idea about Jupiter's Red Spot Junior color change: "an upward and inward diffusion of either a coloured compound or a coating vapour that may interact later with high energy solar photons." • Comet 29P is in outburst, having risen from 14 to 11.5 mag. • There was an impressive fireball over SoCal on Sep. 19. • A minor planet passed close to Uranus, looking like another moon. • Some images (more, more, more and more) of the Moon vs. the Pleiades on Sep. 20 as seen from Europe. • And image processing seems to reveal blue Earth reflected by the ISS ...

Friday, September 19, 2008

Record distance for gamma ray burst: redshift 6.7!

GROND, the Gamma-Ray Burst Optical Near-IR Detector sitting behind an old 2.2-meter telescope in Chile, on September 13 has found the most distant gamma-ray burst ever detected. Alerted by the Swift satellite, the unique instrument taking images in 7 different colors obtained a rough redshift only minutes later, which was confirmed 1½ hours later with the Very Large Telescope. At a redshift of 6.7 GRB 080913 occurred less than 825 million years after the Universe began, and the star that popped off this shot seen across the cosmos died when the Universe was less than one-seventh its present age. The most distant GRB before had a redshift of 6.3 and was was 70 million light years closer to us. • And another astrophysics record of some importance: the least luminous galaxy is the dwarf Segue 1, full of dark matter.

In other news a sensational new image composite of the 1 August TSE has been released by M. Druckmüller, showing coronal streamers for 20 solar radii and many stars, including the Beehive cluster, in the background. • Tonight the Moon once more occults the Pleiades, in Europe only on Saturday morning. • The evening planets as seen from Oz in mid-September.

• Comet Lulin on the 17th - and new page on all comets in the sky right now and how easy or hard they are. (This and this catalog are excellent additions.) • Two bright sun dogs today. • A political article on light pollution as an overlooked environmental problem. • The ISS transiting the Moon and in much detail. • And ... it's alive: ISEE 3 alias ICE, the first spacecraft to visit a comet. Which was in 1985, already in an extended mission!

Wednesday, September 17, 2008

Now all five dwarf planets have real names!

Amidst unresolved issues regarding the circumstances of its discovery, the big and weird Kuiper Belt Object 2003 EL61 has been named Haumea and is now listed as the 5th dwarf planet, joining Pluto, Eris and Makemake in the Kuiper Belt and Ceres in the main belt of asteroids; no further immediate candidates for ascension into this category of solar system bodies introduced only in 2006 are known. The two satellites of Haumea are now called Hi'iaka and Namaka. While the IAU refrains from saying anything about the discoverer(s) of Haumea, the USGS in its list locates the discovery telescope in Spain (where it was imaged but not recognized in 2003) yet also names no people. Mike Brown, who hit upon the same body in 2004, realized that it was something important and is generally credited with the discovery, meanwhile in great detail reiterates his claim of being the rightful owner of this dwarf planet. And indeed the IAU used his 2006 proposal for the name.

In other news this image may be the first one of comet P17/Holmes after its conjunction with the Sun, though it shows only the very core of the coma. • An interesting animation based on Metop data shows how the Kasatochi aerosols swept around the globe - so these weird post-sunset colors imaged by yours truly from Eastern Germany on Aug. 19 could already have been caused by them (which also goes for more German sunset views from that day, this August view from Colorado or another German view of Aug. 30). • Australian views of the evening planets on Sep. 13 and Sep. 1. • Another story on the September Perseids outburst. • New insights into the 19th century eruption of Eta Carinae. • And a view of overlapping galaxies from Hubble - where NICMOS is down and only the WFPC2 working now among the main instruments.

Wednesday, September 10, 2008

Surprise outburst of bright "September Perseids" recorded

As reported first by SpaceWeather, on Sept. 9th a surprising flurry of bright fireballs lit up the skies of North America. The SENTINEL all-sky camera picked up 25 bright meteors in a shower that began at 6:20 UTC and lasted approximately 4 hours. Most appear to have a radiant near Perseus, making this probably an outburst of the September Perseids: these meteors come from an unknown comet and typically produce no more than a handful of dim meteors per hour when the shower peaks on Sept. 8th and 9th; this is the first time they have been caught bursting in this fashion. Most of the meteors recorded by the NASA camera were magnitude -2 or brighter, i.e., as bright as Jupiter or Venus, something a visual observer confirms while others could get more pictures and were able to calculate a radiant. The CBET #1501 also notes detections of outburst by several Radio Forward Meteor Scatter observers in Europe: So this surprise event was well covered - and reminds us that one should always watch the skies ...

In other news there were so many observations of the "naked-eye GRB" that a detailled understanding seems possible as reported at a NASA telecon today. • The volcanic twighlights over Europe are gone but could be back. • Did the HST image an exoplanet in a disk that even Keck couldn't see? • What we've learned (sofar) about asteroid Steins - and how to pronounce its name. • And finally some unusual solar sailing by MESSENGER as it nears its 2nd Mercury encounter.

Sunday, September 7, 2008

All the images taken by Venus Express' quasi-visual camera ...

... VMC have finally, after long delays, started to appear in ESA's public archive which is a huge FTP directory system. To make the images - so far only the UV channel is available, for the first 300 orbits - easier to access the Planetary Society has prepared pages full of thumbnails behind which the original data files wait, in a rather special ".IMG" format (for which free conversion software exists, however). These images could be called the 'ground truth' (although the dark features are caused by still mysterious chemical compounds in the high atmosphere) for groundbased pictures - like those obtained by amateur astronomers which fill archives in Japan or by ESA which has early seen their value and encourages uploading.

Already last year a poster and handout highlighting the high state of the art of amateur planetary imaging surprised many professionals at a conference - the successor of which, by the way, will take place later this month in Münster, Germany. With, for the first time, oral contributions by amateur astronomers, filling a complete session. Fellow amateur astronomers as well as teachers can attend the conference at a drastically reduced fee, by the way, and registration isn't necessary either: just show up in Münster!

In other news there exists another VMC - on Mars Express and back in operation now - which currently delivers the only full disk view of Mars, and amateurs are invited to get the most out of these images. • Jupiter images of late August: from the 30th, the 27th (more) and the 23rd - the latter from Namibia. • Meet the Boattinis: W1 on Sep. 2 and J1 on Sep. 1/2. • Some prominences in early September. • And finally a really weird demonstration that epicycles can do everything if you've got enough of them ...

Saturday, September 6, 2008

Diamond shape, 23+ craters, strange crater chain: asteroid Steins now a world

The first images and other data from Rosetta's first asteroid flyby - the first nominal science phase of the long mission - have just been presented at a news conference at the control center: A sequence of images from the wide angle channel of the OSIRIS camera unveils a diamond-shaped body of 5.9 x 4 km with 23 craters on the side seen that are larger than 200 meters. The two biggest craters are 2 km each: The impacts that caused them must have fractured the whole body. The shape of which had been predicted very well from previous ground- and space-based photometry, but the geometrical albedo of 35±5 % is lower than expected, the body thus a bit larger.

A major mystery has already emerged: There is a crater chain (catena) of 7 craters, something seen only on our Moon and icy outer planet satellites so far. The mechanism that caused it (secondary cratering or an impact of a swarm of bodies) is pretty unclear. There is some regolith on Steins as indicated by shallow, degraded craters that seem to be filled up by some degree (so the cratering history is complex), and the overall color of Steins is grey. A lot more data from several instruments will be downlinked in the coming days, so a fuller understanding of yet another small solar system body will emerge soon from Europe's first visit to an asteroid. Already a few VIRTIS spectra are in - and data from the GIADA dust detector: no impacts at all, as expected for a flyby in 800 km distance. Which missed the target by less than 2 km.

Friday, September 5, 2008

Remote volcano causes unusual sunset colors

The phenomenon has been noted in the past week or so in several continents: An eruption by the volcano Kasatochi in Alaska on August 7 has thrown particles high enough into the atmosphere to cause unusual sunset light effects. These have been amply documented on SpaceWeather today and earlier, still earlier and even earlier, with more reports on sites in Germany and the Netherlands. • A bit higher in the atmosphere the Perseids of 2008 reached a surprisingly high max. ZHR of 110-120: Impressive composite pictures are here (larger and with 35 mm instead of 20 mm focal length), movies here, a fine individual Perseid here and many more pics here. Perseids were also observed impacting on the Moon. • There are also a video meteor summary for July, a daylight fireball in AZ and a potential megacryometeor fall in Jordan discussed here and here (in Arabic). • And again at the edge of space we have NLCs seen from the ISS and bright ISS trash seen from Earth.

In (lots of) other news the first comet discovery by a Swiss amateur astronomer is being hailed (as is a recovery by an Austrian amateur). • We have nice images of C/2007 W1 (Boattini) of Aug. 16 and Aug. 14, marvel about the strange light curve of C/2008 A1 (McNaught) and an outburst of 6P/d'Arrest seen here on Aug. 27 and Aug. 24, still have hope in C/2007 N3 (Lulin), seen on Aug. 17, have a movie of 51P, see 67P and 47P as a pair and C/2005 L3 (McNaught) next to a supernova. • In and beyond the Kuiper Belt two strange bodies have been found, one with an extremely elongated orbit, the other one orbiting backwards.

• The continuing low activity of the Sun is raising eyebrows, but August was not spot-free: A small one had briefly shown up without getting an AR number though. • In amateur astronomy we have a long portrait of an enthusiast from Oz's Gold Coast, a story on light pollution in the NYT Business(!) section and a helpful name resolver tool. • On the practical fron one can worry about leap seconds and celebrate the roll-out of Atlantis which will head to the HST (with Oct. 10 as the new target launch date) as well as the LSST main mirror blank that its creators call "perfect".

• In science a surprising minimum mass for dwarf galaxies has been found, our planetary system may be unusual after all (though this is only a simulation) - and new data confirm the "hockey stick" rise in global temperature: This planet is warmer than it should be. • Finally it may be noted that a strange attempt to reverse the new nomenclature of the solar system didn't generate the desired media impact and was instead seen as a failure, simply boring and way too emotional, for whatever reason. It simply does't depend on what to call it to make a small body fascinating. And if you like it big, how about the largest solar system on Earth, with the planets to scale?

Asteroid visit by Rosetta - today! - and ATV deorbit highlights of September 2008

After August brought us two or three eclipses, September 2008 isn't that rich in natural celestial extravaganzas - so we produce them ourselves when Rosetta flies by asteroid (2867) Steins today at 18:58 UTC. Downlink of images and other data will take a few hours, so it gets really interesting only tomorrow. Also this month the ATV will become a huge man-made meteor - which some plan to observe from the air.
  • Sep. 6, 10:00-11:00 UTC news conference - streamed on the web - on the outcome of the Steins encounter which ESA already is blogging about quite frantically.

  • Sep. 12: Venus 0.4° from Mars; may be a telescopic daytime target.

  • Sep. 13: Uranus in opposition at mag. 5.7.

  • Sep. 19: Venus, Mars and Mercury form a 4° triangle; may be visible telescopically in daytime in Europe, for more Southern regions see below.

  • Sep. 20: Another Plejades occultation by the Moon (in the wee hours for Europe).

  • Sep. 27: Waning crescent Moon visits Saturn - the morning visibility of the latter (with rings at a shallow angle) begins.

  • Sep. 29: Controlled deorbiting of the ATV over the Pacific Ocean - the reentry will be observed from two airplanes for scientific reasons.
Observers in the Southern hemisphere have more planetary fun now with Venus, Mercury and Mars easily seen in the evening sky on Sep. 2 (another picture). From lower Northern sites the trio may be visible very low on the W horizon these days, but binoculars will be needed.

Wrapping up the TSE of 2008 - and two other eclipses since

Many initial reports about the surprisingly well observed total solar eclipse of 1 August 2008 have already been summarized after 3 days and another week, and the most detailled view of the corona has been hailed - here's a third collection of links to reports and pictures from around the world, beginning at an even earlier point than the other two:
  • From the soil of Canada the eclipse could be seen, as a dramatic picture (from Alert) in this story as well as this picture (from Somerset Island) demonstrate.

  • From an icebreaker in the Arctic comes this report.

  • The polar flight out of Germany is featured in this report and this story, plus a widely read German news story.

  • Many more reports and pictures from (low) Russia are here (another "Druckmüllerization"), here (striking contacts composite), here, here, here (very hi-res) and here.

  • From the Russian Altai (close to Mongolia) comes this image, taken here, while other sites were cloudy, as these pictures from another expedition nearby show.

  • From Mongolia come reports of successes from here, here, here, here and here. And Science magazine, of all places, has a long & dramatic story, incl. a narrated slide show ...

  • From China's Xinjiang province we have a more complete picture report by yours truly (and also a new trip report in German), a study of the sky polarization (plus much more from the same trip) and a view from the edge of the zone of totality with extended Baily's beads.

  • From China's Gansu province many more results and reports have been published here and here (with a nice flash spectrum) and here and here and here and here and here (cool foreground) and here.

  • Finally from Xian with a very low Sun comes this report, with the eclipse here. So, as in 2006, totality has been seen from the ground along almost its complete track!
Still not enough reports? You can check other big link collections here and here. The eclipse was also covered on Opposite End of China (earlier; what it is). And the next eclipse is already terrifying small Japanese islands which will strictly control the expected crowds ...

The partial lunar eclipse two weeks later was also observed widely in several continents - and used for some experiments. For example by compositing the segment of the umbra that swept over the Moon its size could be measured; these composites were popular with this deep partial eclipse are rarely before as images here, here, here (also here and annotated) and here show. Others tried High Dynamic Range imaging (here, here and here) or observed stellar occultations or nearby Neptune (more) during the eclipse which was webcast from many places. Yet more nice pictures of the event are here, here, here, here, here, here, here, here, here, here, here and here. The Chinese lunar orbiter, by the way, was not harmed by the event. Want still more recent "eclipses"? The Moon in the Plejades cluster another week later can be seen here (yours truly - no tripod ...), here and here.