Vague reports had already come out at another conference, but today the details have been released about some 45 exoplanet candidates found with the special HARPS spectrograph at the ESO 3.6-meter telescope: they all have a mass below 30 Earth masses and an orbital period shorter than 50 days. Among the discoveries with the radial velocity method is a star having three small planets with 4.2, 6.7 and 9.4 times the mass of the Earth that orbit the star HD 40307 with periods of 4.3, 9.6 and 20.4 days, respectively. "Does every single star harbour planets and, if yes, how many?" planet hunter Michel Mayor from Geneva Observatory now wonders - exactly what he already told an audience in Bonn ½ year ago. Even the most classical of exoplanet hunting techniques, it seems, is now approaching a detection limit of an Earth mass or two.
In other news shatter cones - the largest known - from an ancient impact have been found next to a busy road, though the impact crater is long gone. • A very long paper discusses the long-term light curve of comet Encke. • Io and its shadow in front of/on Jupiter's disk yesterday, also another fine color Jupiter from mid-June. • Olga is just the latest asteroid one dedicated observer saw covering a star. • The light curve of Nova Oph is pretty variable. • Many NLC observations have already been made this year, including the first bright ones and a sighting from Germany.
• Yet another Namibian astronomy report to whet one's appetite for going there once again... • With Discovery back home, the next shuttle will fly to Hubble, if repairs on Discovery's launch pad succedd in time, as is expected. One may also dream about a huge liquid mirror telescope on the Moon in the more distant future. • And finally, in case you missed the link appearing a bit later in a link from here: These are the pics of Venus 3.7' from the solar limb!
Monday, June 16, 2008
Wednesday, June 11, 2008
IAU decides to call Pluto and Eris "plutoids"
Almost two years after the new class of dwarf planets was introduced in the solar system, with Pluto, Eris and Ceres as the first members, another directive from the 2006 General Assembly in Prague has now been fulfilled: the subclass of dwarf planets residing in the Kuiper belt has been named "plutoids". Furthermore it was decided that any Solar System body having a semimajor axis greater than that of Neptune and an absolute magnitude brighter than H=+1 mag. will be considered to be a plutoid (which has implications for the formalities by which it will be given a proper name). The IAU did not announce any new entries into the dwarf planet/plutoid class or when that will happen - but it should be only a matter of time until 2003 EL61 and 2005 FY9 are accepted; see this inofficial list once compiled by this blogger.
In other news this blog has just learned about successful imaging of Venus 3.7 arc minutes(!!!) from the solar limb yesterday morning: The photographer masked part of his DSLR's chip with a metal strip, used a neutral density filter and Herschel wedge with his refractor telescope (to keep the heat away from the electronics) and made long exposures ... • Amateur astronomers played a role in triggering crucial radio observations of dwarf nova SS Cyg. • There is now a new sunspot group which has since been given the number (10)998. • Jupiter with an 8" telescope and at low elevation from Germany - still pictures like these were possible last night, or methane observations; here is a collection. • Another Namibian astronomy expedition report. • And selected sky pictures from above.
In other news this blog has just learned about successful imaging of Venus 3.7 arc minutes(!!!) from the solar limb yesterday morning: The photographer masked part of his DSLR's chip with a metal strip, used a neutral density filter and Herschel wedge with his refractor telescope (to keep the heat away from the electronics) and made long exposures ... • Amateur astronomers played a role in triggering crucial radio observations of dwarf nova SS Cyg. • There is now a new sunspot group which has since been given the number (10)998. • Jupiter with an 8" telescope and at low elevation from Germany - still pictures like these were possible last night, or methane observations; here is a collection. • Another Namibian astronomy expedition report. • And selected sky pictures from above.
Monday, June 9, 2008
Solar minimum unusually deep/long after all?
When the question was raised in May whether the current minimum of solar activity was unusually low, the reply from NOAA was that "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." But at a solar conference in Montana a month later things were apparently seen differently, at least according to a press release the hosting university put out today: "The scientists said periods of inactivity are normal for the sun, but this period has gone on longer than usual. [...] The next cycle is just beginning and is expected to reach its peak sometime around 2012. Today's sun, however, is as inactive as it was two years ago, and scientists aren't sure why." The release stresses the lack of knowledge about the Sun's 'plans' but mentions the Maunder minimum of the 17th century ...
In other news here are some observations of the 'other' comet Boattini currently around 11th mag. Meanwhile the 'old' Boattini is near M 41, only visible deep South at around 5th mag. • The first bright NLCs of the year have been seen in Ireland - and a weird halo in Finland.
In other news here are some observations of the 'other' comet Boattini currently around 11th mag. Meanwhile the 'old' Boattini is near M 41, only visible deep South at around 5th mag. • The first bright NLCs of the year have been seen in Ireland - and a weird halo in Finland.
Saturday, June 7, 2008
Venus racing towards the solar limb, still caught today ...
Eight hours from now Venus will slip behind the limb of the Sun, a rare event that happens only every 8 years and only for a few decades (in the vicinity of the transit of Venus 'seasons'). As already explained here observing the "show" may or may not be possible at all, will definitely require special equipment and is very risky for both equipment and observer. Then again, Venus has been imaged again today, just 25 arc minutes from the solar limb and 13 hours before disappearing behind it! Owners of prominence coronagraphs and full-disk H-Alpha telescopes alike might give it a try, and if Venus won't show up at all in raw images which show prominences (there is a good one near the Eastern limb right now, and on June 4 a spectacular one was observed) and/or the chromosphere well, try to overexpose. Experiments with other (wider-band) filters are at your own risk, of course. Now here is the timeline, calculated with Horizons for Bonn, Germany:
In other news we have a nice video of a stellar occultation by (618) Elfriede, the young Moon on June 4 (again) and Jupiter on June 2. • A detailled - but controversial - paper on Holmes' outburst has been published in the ICQ while there are new thoughts on the origin of the Kappa Cygnid meteors and the famous fresh Carancas crater has been visited again, 8 months after the bizarre mini-impact in Peru. • A 5 gigapixel IR image mosaic of the Milky Way has been published in several ways: through a viewer and as a mega-poster at at conference. • And here is the ISS on June 3 (also reported internationally).
- First contact (Venus and Sun limbs touch) - 5:07½ UTC - solar elevation 14°
- Mid-entry - 5:14 UTC - solar elevation 15°
- Second contact (Venus gone) - 5:20½ - solar elevation 16°
In other news we have a nice video of a stellar occultation by (618) Elfriede, the young Moon on June 4 (again) and Jupiter on June 2. • A detailled - but controversial - paper on Holmes' outburst has been published in the ICQ while there are new thoughts on the origin of the Kappa Cygnid meteors and the famous fresh Carancas crater has been visited again, 8 months after the bizarre mini-impact in Peru. • A 5 gigapixel IR image mosaic of the Milky Way has been published in several ways: through a viewer and as a mega-poster at at conference. • And here is the ISS on June 3 (also reported internationally).
Tuesday, June 3, 2008
STOP PRESS: Spitzer unravels Milky Way structure - only two arms!
Here it is: This is what our Milky Way looks like when seen from above! This artist's view, based on infrared observations with the Spitzer Space Telescope, is being presented at a press conference at the AAS Meeting in St. Louis this hour, and the embargo is now lifted. The images are "revealing that [the Milky Way] has just two major arms of stars instead of the four it was previously thought to possess," says an accompanying press release: "Since the 1950s, astronomers have produced maps of the Milky Way. Those early models were based on radio observations of gas in the galaxy, and suggested a spiral structure with four major star-forming arms, called Norma, Scutum-Centaurus, Sagittarius and Perseus. In addition to arms, there are bands of gas and dust in the central part of the galaxy. Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms. [...]
Large infrared sky surveys in the 1990s led to some major revisions of these models, including the discovery of a large bar of stars in the middle of the Milky Way. Infrared light can penetrate through dust, so telescopes designed to pick up infrared light get better views of our dusty and crowded galactic center. In 2005, [Robert] Benjamin [of the University of Wisconsin] and his colleagues used Spitzer's infrared detectors to obtain detailed information about our galaxy's bar, and found that it extends farther out from the center of the galaxy than previously thought. The team of scientists now has new infrared imagery from Spitzer of an expansive swath of the Milky Way, stretching 130 degrees across the sky and one degree above and below the galaxy's mid-plane. This extensive mosaic combines 800,000 snapshots and includes over 110 million stars.
Benjamin developed software that counts the stars, measuring stellar densities. When he and his teammates counted stars in the direction of the Scutum-Centaurus Arm, they noticed an increase in their numbers, as would be expected for a spiral arm. But, when they looked in the direction where they expected to see the Sagittarius and Norma arms, there was no jump in the number of stars. The fourth arm, Perseus, wraps around the outer portion of our galaxy and cannot be seen in the new Spitzer images. The findings make the case that the Milky Way has two major spiral arms, a common structure for galaxies with bars. These major arms, the Scutum-Centaurus and Perseus arms, have the greatest densities of both young, bright stars and older, so-called red-giant stars. The two minor arms, Sagittarius and Norma, are filled with gas and pockets of young stars. Benjamin said the two major arms seem to connect up nicely with the near and far ends of the galaxy's central bar."
Large infrared sky surveys in the 1990s led to some major revisions of these models, including the discovery of a large bar of stars in the middle of the Milky Way. Infrared light can penetrate through dust, so telescopes designed to pick up infrared light get better views of our dusty and crowded galactic center. In 2005, [Robert] Benjamin [of the University of Wisconsin] and his colleagues used Spitzer's infrared detectors to obtain detailed information about our galaxy's bar, and found that it extends farther out from the center of the galaxy than previously thought. The team of scientists now has new infrared imagery from Spitzer of an expansive swath of the Milky Way, stretching 130 degrees across the sky and one degree above and below the galaxy's mid-plane. This extensive mosaic combines 800,000 snapshots and includes over 110 million stars.
Benjamin developed software that counts the stars, measuring stellar densities. When he and his teammates counted stars in the direction of the Scutum-Centaurus Arm, they noticed an increase in their numbers, as would be expected for a spiral arm. But, when they looked in the direction where they expected to see the Sagittarius and Norma arms, there was no jump in the number of stars. The fourth arm, Perseus, wraps around the outer portion of our galaxy and cannot be seen in the new Spitzer images. The findings make the case that the Milky Way has two major spiral arms, a common structure for galaxies with bars. These major arms, the Scutum-Centaurus and Perseus arms, have the greatest densities of both young, bright stars and older, so-called red-giant stars. The two minor arms, Sagittarius and Norma, are filled with gas and pockets of young stars. Benjamin said the two major arms seem to connect up nicely with the near and far ends of the galaxy's central bar."
"Real demon star" Epsilon Aurigae: next eclipse in 2009 - and "doom" mid-century?
They happen only every 27 years, and the next one is due in 2009-11: eclipses in the strange Epsilon Aurigae system that is easily visible to the naked eye - and at the same time a topic of intense research and also of another press conference during the AAS Meeting in St. Louis in the past hour. "Observations over the coming three years, when the mysterious star undergoes a once-per-generation eclipse event, may hold the secret to the extreme changes detected during the past few decades," the summary goes, wich includes the prediction - not overly stressed in the PC - that "the bright northern star called epsilon Aurigae is headed for a 'doomsday event' within a few decades." The spectrum of epsilon Aurigae looks like a normal F supergiant star with12 to 15 times the mass of the Sun. The mass ratio in the binary is close to one, implying that the companion is about 12 to 14 solar masses as well. Epsilon Aurigae exhibits eclipses like the "demon star" Algol every 27 years, which last for nearly 2 years. The next one starts in August 2009, and should run through May 2011.
The 12 to 14 solar mass second "star" is largely invisible, however! The secondary is probably a huge dark disk, not a sphere, requiring a massive central object(s) to stabilize it. Normal eclipsing binary star analysis suggests that the secondary is about 10 AU across but does not emit anywhere near the amount of light expected from a star of its size (nor is it a collapsed object: no X-rays). Another observation: Eps Aur shows low amplitude quasi-periodic light variations, similar to Cepheid variable stars. Currently its light variations are on a 67 day cycle, but - key point - were near 96 days during the last two decades: Something is accelerating in this system! At this rate, variations will become very rapid within six decades, perhaps cataclysmically so. Observations during the last eclipse furthermore suggest that the F supergiant star may be shrinking by about 1/2% per year. The duration of total eclipse (during which the F star is partially covered by the disk shaped companion) has increased by about 25% between the 1956 and 1983 eclipses. Despite this, the overall length of the total plus partial phases of eclipse - especially the time where the F star moves out from the cover of its partner - has gotten shorter!
If these trends continue, the F star will come out of eclipse (from totality) in only 1 or 2 weeks during 2011, but will still take 140 days or so to move from the beginning of the eclipse to totality next year, autumn. A 10% change in luminosity can result from a 5% change in radius or a 2.5% change in temperature. At an estimated distance of 625 pc, and assuming the F supergiant star has a typical diameter, the implied angular diameter is 3 milli-arcseconds (mas). Modern optical interferometers are capable of measuring down to fractions of 1 mas, close to that 5% change (0.15 mas) anticipated, and these measurements are underway: They could confirm that the F star's rapid evolution is causing the accelerating light changes. It should be bifurcated by the eclipse-causing disk, if indeed it is a disk, and state-of-the-art interferometers like CHARA on Mt.Wilson and MROI at Socorro should be able to monitor that. But at the same time when this high-end astronomy will be tried, people - 2009 being the International Year of Astronomy - all over the world will also be asked to monitor the beginning eclipse in a world-wide effort of "citizen science".
In other news another Nova Ophiuchi has been discovered, rather faint. • Daring astrophotographers have caught Venus 2° from the Sun as a disk, even with hints of NIR detail on it. • Images of Jupiter with and without the red spot trio on June 3 and June 1 from Europe and April 30 from Namibia. • Comet Boattini is now at 4.9 mag. and travels amongst star clusters for Southern observers. • Today's New Moon is the closest of the year. • Nice prominences on June 2 - and (better late than never) pictures of the annular eclipse 2006 in Suriname, total eclipse 2005 in the Pacific and many earlier eclipses by K. Delcourte (accompanied by lots of travel impressions). • EPOXI imaged the Earth-Moon system on May 29 as an exoplanet detection analog experiment. • How the Discovery-ISS docking looked like yesterday from New Zealand, and the ISS passing Saturn in a little movie. • And finally a strange exhibition where (spy) satellite watching meets art ...
The 12 to 14 solar mass second "star" is largely invisible, however! The secondary is probably a huge dark disk, not a sphere, requiring a massive central object(s) to stabilize it. Normal eclipsing binary star analysis suggests that the secondary is about 10 AU across but does not emit anywhere near the amount of light expected from a star of its size (nor is it a collapsed object: no X-rays). Another observation: Eps Aur shows low amplitude quasi-periodic light variations, similar to Cepheid variable stars. Currently its light variations are on a 67 day cycle, but - key point - were near 96 days during the last two decades: Something is accelerating in this system! At this rate, variations will become very rapid within six decades, perhaps cataclysmically so. Observations during the last eclipse furthermore suggest that the F supergiant star may be shrinking by about 1/2% per year. The duration of total eclipse (during which the F star is partially covered by the disk shaped companion) has increased by about 25% between the 1956 and 1983 eclipses. Despite this, the overall length of the total plus partial phases of eclipse - especially the time where the F star moves out from the cover of its partner - has gotten shorter!
If these trends continue, the F star will come out of eclipse (from totality) in only 1 or 2 weeks during 2011, but will still take 140 days or so to move from the beginning of the eclipse to totality next year, autumn. A 10% change in luminosity can result from a 5% change in radius or a 2.5% change in temperature. At an estimated distance of 625 pc, and assuming the F supergiant star has a typical diameter, the implied angular diameter is 3 milli-arcseconds (mas). Modern optical interferometers are capable of measuring down to fractions of 1 mas, close to that 5% change (0.15 mas) anticipated, and these measurements are underway: They could confirm that the F star's rapid evolution is causing the accelerating light changes. It should be bifurcated by the eclipse-causing disk, if indeed it is a disk, and state-of-the-art interferometers like CHARA on Mt.Wilson and MROI at Socorro should be able to monitor that. But at the same time when this high-end astronomy will be tried, people - 2009 being the International Year of Astronomy - all over the world will also be asked to monitor the beginning eclipse in a world-wide effort of "citizen science".
In other news another Nova Ophiuchi has been discovered, rather faint. • Daring astrophotographers have caught Venus 2° from the Sun as a disk, even with hints of NIR detail on it. • Images of Jupiter with and without the red spot trio on June 3 and June 1 from Europe and April 30 from Namibia. • Comet Boattini is now at 4.9 mag. and travels amongst star clusters for Southern observers. • Today's New Moon is the closest of the year. • Nice prominences on June 2 - and (better late than never) pictures of the annular eclipse 2006 in Suriname, total eclipse 2005 in the Pacific and many earlier eclipses by K. Delcourte (accompanied by lots of travel impressions). • EPOXI imaged the Earth-Moon system on May 29 as an exoplanet detection analog experiment. • How the Discovery-ISS docking looked like yesterday from New Zealand, and the ISS passing Saturn in a little movie. • And finally a strange exhibition where (spy) satellite watching meets art ...
Monday, June 2, 2008
STOP PRESS: Smallest planet of smallest star (or sub-star) found
A press conference is still underway in St. Louis at the 212th AAS Meeting in which D. Bennett has just announced the discovery of a planet of roughly 3 Earth masses orbiting a star or brown dwarf of 6±3 percent of a solar mass; with a high probability the mass is < 8%, so it's probably a brown dwarf. The discovery was made with a new wide-field telescope by the MOA collaboration in New Zealand which images the whole galactic bulge every hour, looking for microlensing events and signatures of planets in these. The detailled paper is rather cautious, though: "the observational coverage of the planetary deviation is sparse and incomplete, and the radius of the source was estimated without the benefit of a source star color measurement. As a result, the 2-sigma limits on the mass ratio and the finite source measurements are weak. Nevertheless, the microlensing parallax signal clearly favors a sub-stellar mass planetary host, and the measurement of finite source effects in the light curve supports this conclusion." This would be the 7th exoplanet detection via microlensing, though the mass of the planet is ill-defined at 3.3 (+4.9/-1.6) Earth masses and does not necessarily set a new record.
Sunday, June 1, 2008
Venus anti-transit of the Sun invisible(?) highlight of June
We are exactly half-way between the two transits of Venus of 2004 and 2012 - which means that in June 2008 Venus will pass behind the Sun during its superior conjunction. Astrophotographers have wondered for months whether it might be possible - with highly specialized equipment (don't try it with any regular optical system!!!Such experiments are really dangerous) - to image the tiny but very bright and fully illuminated disk of the planet approaching the solar limb and perhaps even catch it while disappearing behind the chromosphere. One system that may be able to do it is the Unigraph, a new refractor design with very little internal scattering which permits prominence photography in extreme resolution - and in white(!) light. (I once saw these images at a conference but just can't find any on the web.) Still unanswered is the question whether Venus would show up in such an image, together with the chromosphere or even a conveniently placed prominence ... The highlights of June 2008:
- June 8, about 6:15 UTC: Venus disappears behind the solar limb as calculated with Horizons for a geocentric observer - should be nearly the same everyone on the planet.
- June 8, evening UTC: The Moon (4 days old), Regulus and Saturn "line up", with Mars nearby.
- June 10, around 1:00 UTC: Venus emerges again behind the Sun (because Venus is much farther from the Earth, such an 'antitransit' takes two days, not a few hours like a transit).
- June 20: Dwarf planet Pluto in opposition to the Sun, at 13.9 mag.
- June 30: One hundred years ago the Tunguska event hit Siberia - spare a thought for all those trees felled by an astronomically speaking insignificant cosmic airburst.
Thursday, May 29, 2008
Rare stellar occultation by Neptune's Triton observed!
These events happen only once a decade or so and are of high scientific value for understanding the atmosphere of Triton, Neptune's largest satellite - and now word has come out that another such observing campaign has been quite successful! (Please pardon the mix of French, English and German - and you may have to save the image to disk and open it with a PDF viewer.) On May 21 a 13 mag. star was occulted (alt. diagram, and now Bruno Sicardy reports: "For the first time in the last 11 years, Triton's atmosphere has been successfuly detected from two stations in Namibia (Hakos and Tivoli, summing five telescopes), and from two mobile stations set up at La Reunion Island (Maido and La Fournaise, summing four telescopes). [...]
One of the main scientific issues is now to see whether Triton's atmosphere have suffered drastic changes since 1997, knowing that the satellite reached an 'extreme' southern summer solstice in 2000. Then, the sub-solar latitude reached ~50°S. This happens every 600 years or so, and may have significantly heated up the nitrogen ice cap, triggered an enhanced geyser activity in the south polar regions of Triton, and induced a related pressure increase of the nitrogen atmosphere. [...] Two other stations in Namibia (Windhoek and Grunau) were clouded out. All the stations set up in South Africa (SAAO, Cape Town, Springbok) were clouded out. A third station in La Reunion (Les Makes) was also clouded out." There is also an update on the mutual occultations of the satellites of 2003 EL61.
In other news there is now a press release on the fastest-rotating asteroid reported here a week ago, stressing that this was an amateur discovery using the Faulkes telescopes. • Comet Boattini looks strange, at least with heavy image processing. • The lightcurve of comet Pons-Winnecke is going down again; here are pictures of May 23 and other dates. • A nice sungrazing comet was detected on May 23. • There's a Nova Oph 2008, but only at 10th mag: map, alert, observation, picture. • And finally some recent hi-res ISS pics: On May 31 shuttle Discovery should join the view.
One of the main scientific issues is now to see whether Triton's atmosphere have suffered drastic changes since 1997, knowing that the satellite reached an 'extreme' southern summer solstice in 2000. Then, the sub-solar latitude reached ~50°S. This happens every 600 years or so, and may have significantly heated up the nitrogen ice cap, triggered an enhanced geyser activity in the south polar regions of Triton, and induced a related pressure increase of the nitrogen atmosphere. [...] Two other stations in Namibia (Windhoek and Grunau) were clouded out. All the stations set up in South Africa (SAAO, Cape Town, Springbok) were clouded out. A third station in La Reunion (Les Makes) was also clouded out." There is also an update on the mutual occultations of the satellites of 2003 EL61.
In other news there is now a press release on the fastest-rotating asteroid reported here a week ago, stressing that this was an amateur discovery using the Faulkes telescopes. • Comet Boattini looks strange, at least with heavy image processing. • The lightcurve of comet Pons-Winnecke is going down again; here are pictures of May 23 and other dates. • A nice sungrazing comet was detected on May 23. • There's a Nova Oph 2008, but only at 10th mag: map, alert, observation, picture. • And finally some recent hi-res ISS pics: On May 31 shuttle Discovery should join the view.
Saturday, May 24, 2008
Possible outburst of comet 7P/Pons-Winnecke
According to photometric measurements by G. Muler the inner coma of comet 7P has brightened by several magnitudes in recent days - but don't panic yet: It's still only at 14 to 15 (instead of 17 to 18), and there is no independent confirmation yet. • Meanwhile Boattini could read 3.9 mag. soon, if the current brightening trend holds. The Southern hemisphere is heavily favored now.
In other news here are fuzzy color images of Jupiter this morning and more methane-band images of May 7 (scroll down), clearly showing the trio of (red) storms. Also: Mars in the Beehive cluster (later). • A grant will enable further Pluto occultation observations. • Now is the time to see the ISS and image it, be it trailing or in high and even higher resolution. For comparision, here are some ISS flyover movies from 2006, 2007 and 2008 (more) plus a clip from a documentary on how such imaging is done. (The claim that these folks are unique is rubbish, of course.)
• Alert #1: On German TV there will be a show on amateurs in science on Sunday, including two amateur astronomers (a UFO investigator and comet hunter D. Levy) - the ARD-Mediathek may carry the program live or have it for download afterwards. • Alert #2: Here are links several sources for timely Phoenix information during and after its EDL on Sunday/Monday (forgetting another good one by Spaceflight Now); a consolidated timeline of anticipated events can be found here, where also some live-blogging is planned!
In other news here are fuzzy color images of Jupiter this morning and more methane-band images of May 7 (scroll down), clearly showing the trio of (red) storms. Also: Mars in the Beehive cluster (later). • A grant will enable further Pluto occultation observations. • Now is the time to see the ISS and image it, be it trailing or in high and even higher resolution. For comparision, here are some ISS flyover movies from 2006, 2007 and 2008 (more) plus a clip from a documentary on how such imaging is done. (The claim that these folks are unique is rubbish, of course.)
• Alert #1: On German TV there will be a show on amateurs in science on Sunday, including two amateur astronomers (a UFO investigator and comet hunter D. Levy) - the ARD-Mediathek may carry the program live or have it for download afterwards. • Alert #2: Here are links several sources for timely Phoenix information during and after its EDL on Sunday/Monday (forgetting another good one by Spaceflight Now); a consolidated timeline of anticipated events can be found here, where also some live-blogging is planned!
Thursday, May 22, 2008
One rotation every 43 seconds: the fastest rotator known in the solar system
This news item - from today's Electronic Telegram No. 1382 of the Central Bureau for Astronomical Telegrams - could make you dizzy: Photometric "observations of minor planet 2008 HJ obtained using the 2.0-m Faulkes Telescope South during Apr. 28-29, reveal that this Apollo-type object has the shortest known rotation period of any natural body in the solar system at 42.67±0.04 s. It exhibits a light curve comprised of two similar maxima and minima with an amplitude of 0.8 mag. [...] 2008 HJ has presumed approximate dimensions 12 x 24 m. The fastest previously known rotator was 2000 DO8, which has a rotation period of 78 s".
In other news a third Red Spot has formed on Jupiter, close to the other two - and this Berkeley/Keck press release hails the observations of amateurs, augmenting Hubble and Keck data. Indeed in late April a German methane-band movie clearly shows the storm triplet! • Mars is now inside the Beehive star cluster. • A nice prominence movie from yesterday. • A quasar at z=3.6 has been observed visually with an 18" scope. • A Nature commentary on amateur astronomers today. • And the final HST shuttle mission is now planned for Oct. 8.
In other news a third Red Spot has formed on Jupiter, close to the other two - and this Berkeley/Keck press release hails the observations of amateurs, augmenting Hubble and Keck data. Indeed in late April a German methane-band movie clearly shows the storm triplet! • Mars is now inside the Beehive star cluster. • A nice prominence movie from yesterday. • A quasar at z=3.6 has been observed visually with an 18" scope. • A Nature commentary on amateur astronomers today. • And the final HST shuttle mission is now planned for Oct. 8.
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