The Cosmic Mirror
By Daniel Fischer
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Current mission news: MGS (latest pictures!) + Cassini + Stardust

European lunar orbiter SMART-1 to impact on September 3
The nominal crash time is 5:41 UTC: impact details, a Call for Observations, ESA Releases of Aug. 31, Aug. 29, Aug. 25, Aug. 17 and Aug. 16, EXPReS, PPARC and NHM Releases, Science@NASA and coverage of Sep. 1: NwS, PSB. Aug. 31: Belfast Telegr., SC. Aug. 30: S&T, AFP. Aug. 29: Dsc. Aug. 28: W. Aug. 25: BBC. Aug. 24: NwS. Aug. 22: Cosmos. Aug. 21: G, NZ. Aug. 17: Z. Also lunar image & science releases of Aug. 22, 18 and 8, coverage of Aug. 22: SC and a paper (PDF, 13 pg.) on the highlights. LCROSS preview: Ames PR.
Update # 300 of Friday, September 1, 2006
Posted in part from the General Assembly of the IAU in Prague, Czech Republic
Planet defined: there are 8, period / Space pioneer van Allen dead at 91 / Ho settled?

There you have it: 8 planets and 3+ "dwarf planets"

"Cleared the neighbourhood" and "nearly round" define a planet / "Dwarf planets" are not planets, i.e. Pluto isn't one / Pluto & fellow large TNOs also form yet another new - and yet to be named - category

In the end, the General Assembly of the International Astronomical Union had four resolutions on the (first-ever scientific) definition of the word planet to vote on on August 24, 2006, one after the other: The IAU executive had, after considerable struggle, come up with a kind of compromise text but separated out several particularly controversial aspects in order to increase the chances of the planet definition itself to pass. Following the fast and furious failure of the original idea (see Aug. 16 story) to convince planetary experts on August 18 (see following story) and more public and internal debates over the following days, resolution 5a presented on the morning of Aug. 24 was much closer to the alternative that had 'won' in the Aug. 18 debate. It still included the introduction of a new category of solar system bodies bridging the real planets - big, about round, totally dominating their neighborhood - and the small solar-system bodies, but also acknowledges that we live in a solar system and cannot look at each inhabitant as an isolated body like stellar astronomers usually can:
  • A "planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.

  • A "dwarf planet" is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.

  • All other objects except satellites orbiting the Sun shall be referred to collectively as "Small Solar-System Bodies" [with borderline cases between "dwarf planet" and "small solar-system body" - most asteroids and TNOs and all comets make up the latter group - to be handled by "an IAU process"].
A final brief debate was held in the August 24 General Assemby, mainly to clarify details in resolution 5a: e.g. the expression "dwarf planet" was only introduced because no one could or would come up with a new word and should in now way be read as 'small (real) planets'. "Nearly round" was added because that concept is easier to communicate to the public than hydrostatic equilibrium. And "small solar-system object" is understood only as an umbrella term, with expressions like minor planet, asteroid and comet still permitted in the future. One astronomer pleaded with the audience that the resolution needed to pass in its new form or all astronomers would look like idiots to the world. And pass it did: About 90% of the roughly 420 IAU members present (less than 5% of the worldwide membership, by the way) carried 5a. At 15:19 CEST (13:19 UTC) thus Pluto ceased to be a planet. Or almost: Resolution 5b would have made "planet" an umbrella term for both the 8 "classical" planets and the newly introduced "dwarf planets", thus saving Pluto's planet status - but it failed by a wide margin at 15:34.

The object now formerly known as the 9th planet got a somewhat convoluted consolation price with resolution 6a, however, that passed 237 : 157 (with 17 abstentions) at 16:00: Yet another category of Pluto-sized transneptunian "dwarf planets" will be established, to recognize Pluto as its prototype. Those giant transneptunes will not, however, be called "plutonian objects" as resolution 6b would have introduced - which failed at 16:12 CEST by a minute margin. (By how much was never established as the vote counting had gotten surprisingly chaotic at that point, and eventually the General Assembly voted not to vote again on 6b ...) So another IAU commission will have to come up with a name for these bodies - which will certainly not be "plutons": Planetologists, geologists (who already use the term) and linguists alike had already voiced strong objections. Anyway: There is now a definition for planet, valid at least in the solar system, and Pluto is something else. Not that anything has changed in the Universe itself, of course: It was all about semantics - but perhaps some non-astronomers and astronomers alike are now thinking a bit deeper about the strange worlds that make up the solar system than before ...

Posted on August 18 from the IAU GA

Planet redefinition proposal defeated by alternative idea in internal test vote!

The first debate at the IAU General Assembly in Prague on the resolution to (re)define the word "planet" as proposed by the Executive Council (EC), in which only planetary scientists participated, ended on August 18 with a test poll in which an alternative proposal defeated the EC proposal with at least 60% of the votes. The debate had been intense but at a high level, bringing up many of the critical issues which had been raised in the past two days here and around the world: While the authors of the resolution again defended its strict scientific basis they had intended, with only the physical state of a body being important and not where it resides, a key objection was that the public at large would just not understand it. And it is the public that the whole trouble is about: Planetary science does not need a strict dividing line between planet and non-planet (though those IAU committees that have to name various solar system objects actually do).

The more popular alternative, proposed by Gonzalo Tancredi and Julio Fernández and underwritten by several other astronomers, would require that a planet be by far the largest body in the local population (and also big enough to be round) - a body being only round from its own gravity but accompanied by others of similar size would not qualify and be called something else (a fate which would then await Pluto and all the other giant TNOs, plus all asteroids). Various other ideas were mentioned in the debate, such as keeping it really simple by e.g. - an unpopular proposal by Paul Weissman - not changing anything at all and 'grandfathering in' Pluto as an odd planet and the last one ever to be added to the list (sorry, UB313). Or calling everything a planet which has an absolute magnitude larger than zero (an idea by Dave Tholen not put up for vote either, which would have made 2003 UB313 and 2005 FY9 join Pluto as planets). Now that the EC proposal has not passed the muster of the planetary community, all bets are off what will happen next week ...

Posted on August 16 from the IAU GA

Controversial planet definition proposal out in the open

Would make Ceres, Charon, 2003 UB313 planets and keep Pluto one, but in a 'dwarf' category / 'minor planets' would no longer exist / IAU General Assembly may vote on resolution this month

How would you like a solar system with 8 classical, 4 dwarf and no minor planets, with the first asteroid Ceres being upgraded to planet status (but none of the others, including Vesta which is much brighter in our sky) and not only Pluto but also its largest satellite Charon and the super-Pluto 2003 UB313 (see Update #290 lead) but none of the other Kuiper Belt Objects in the 1000-km class being planets, too? This is, in essence, what a group of 7 astronomers, historians and authors is proposing to the General Assembly of the International Astronomical Union taking place right now in Prague. There would also be a kind of waiting list for another dozen distant objects that may fulfill a complex new set of planethood criteria - and the term 'minor planets' would no longer be used at all since these 'small bodies' are no planets.

The select few solar system inhabitants called Planets, however, would not only be divided into classical and dwarf planets but also into normal planets and 'plutons' which are large Kuiper belt objects. (How much easier would it have been if Pluto and all the other Kuiperoids would just have become minor planets as proposed by the Minor Planet Center in 1999 [see Update #119 story 2], but no, Pluto had to keep its major planet status for some reasons.) There will be two debates of the proposal at the General Assembly and perhaps a vote on Aug. 24 - some key planetary astronomers the Cosmic Mirror had talked to about the proposal in recent days were all highly skeptical, while its authors are convinced it will pass. Whether the astronomical world at large, let alone the general public, would follow along, would then be a different matter ...

The outcome of the vote, the revised resolution(s) presented early on Aug. 24 and reaction to the vote from Caltech (Brown's personal take), JHU, NASA [alt.], IU, NJIT, UNT and PS.
The original resolution from Aug. 16 and many explanatory documents are linked from an IAU Press Release and are included in full in the conference newspaper on p. 4-5 (all issues & supplements) - the result were numerous comments, also from IWU and UB313 discoverer Mike Brown.
If it helps: current papers on planethood and TNOs by Basri & Brown, Soter, Pecnik & Broeg and Chiang & al. - and USNO on "When Did the Asteroids Become Minor Planets?" plus a "Preserve Pluto" site and a cartoon ...

Coverage after the vote was made, of Sep. 1: S&T, ABC, RMN, AFP. Aug. 31: Breeze (OpEd), NwS, SC (earlier, blog), Missourian, Dallas MN, Ledger. Aug. 30: NG, Cox, G. Aug. 29: Prospect, Illinoisian, Ocolly, RegMail, ABS, HampRoads, MiningG, LAT, HeraldN, Courant, OC Reg, OaklP, ManEater. Aug. 28: USAT, SpR, JoplinG, Texan, IANS, APOD, RR*, HutchNews. Aug. 27: SFC. Aug. 26: BangorD, Yomiuri, HC, W. Aug. 25: BBC, SFG, KBCI, VoA, Scotsman, WildCat, BerkshE, Times, CS, RMN, DNA India, WP (other story), KansasC*, PhilInq, Cosmos, MercN, PostCresc, Teness, PhillyNews, G, PostGaz, PalmBP, NwS, ABC, NW, PhysWeb, SMH, Exponent, Age, BBJ, DeseretN, NJ, WichitaE, RegGrd, TimesD, Coloradoan. Aug. 24: S&T, PS, Ast., BBC, ScN, NPR, PBS, SFG, T, G, NG, HC, Bus.Week, AP, SC (more, earlier), ST, NAI, NZ, *, W, RP, BdW.

Coverage while the debate was raging, of Aug. 23: Reg., NewsObs, Scotsm., SC, ST, NAI, Standard, TP. Aug. 22: NwS (earlier), S&T, WP, LSB, USAT, Xinhua, AA, AC. Aug. 21: NwS, BGN, LAT, PSB, Xinhua, NAI. Aug. 20: Time, LAT, Berks.Eagle. Aug. 19: SC, ScN, CNET, Ast. Aug. 18: S&T, NwS, SC (earlier), J.G. Aug. 17: LSB, LAT, WP, CSM, SC (other story), Age, Z.

Coverage of Aug. 16, the day the original resolution was made public: S&T, PS, ScN, WP (OpEd), NwS (sidebar), Time Blog, HC, BBC (sidebar), GFH, G, SC, SFC, BadAstro, AP, ST, NAI, BdW, NZ, RP, Stern (more German stories via AstroTreff, plus a parallel discussion on Pre-release stories: G [alt.] (more), BBC, AP, RMN (earlier), AFP, SC, NPR.

Space pioneer James A. Van Allen dead at 91

Dr. James A. Van Allen, a space pioneer and professor of physics Aug. 9, 2006, of heart failure; he was 91. The highlight of Van Allen's long and distinguished career was his use of instruments carried aboard the first successful U.S. satellite, Explorer 1, in 1958 to discover bands of intense radiation - later known as the Van Allen radiation belts - surrounding the Earth. It came at the height of the U.S.-Soviet space race and literally put the United States on the map in the field of space exploration. Among the other accomplishments of which he was most proud was his 1973 first-ever survey of the radiation belts of Jupiter using the Pioneer 10 spacecraft and his 1979 discovery and survey of Saturn's radiation belts using data from the Pioneer 11 spacecraft.

Ever a critic of manned space flight, Van Allen the scientist described himself as "a member of the loyal opposition" when it came to discussions of big-budget space programs, declaring that space science could be done better and more cheaply when left to remote-controlled, unmanned spacecraft. NASA's move toward cheaper, more focused unmanned spacecraft during the 1990s was, at least in part, a result of Van Allen's advocacy. Though vam Allen retired from active teaching in 1985, he continued to monitor data from Pioneer 10 throughout the spacecraft's 1972-2003 operational lifetime and serve as an interdisciplinary scientist for the Galileo spacecraft, which reached Jupiter on Dec. 7, 1995.

Univ. of Iowa obit, AIAA Statement, PS, Press-Cititzen, PhysWeb, Desm.R., Times, Chic.Trib., G, SC, AP, ST.

Premature talk about a smaller Hubble constant

A new distance determination to the galaxy Messier 33 based on a single binary star system and indicating a value 15% higher than expected has widely been reported as evidence that the Hubble constant is not that settled after all and that the Universe may be 15% bigger and older. Highly unlikely, actually, given the multiple means by which the current value of about 72 km/s/Mpc has been established in recent years - and indeed, a few days later two new determinations of the Hubble contant have been published, both largely confirming the old value! They are based on an entirely different techniques, the SZ effect in one case and Cepheids in the other paper in which the distance to the radio galaxy Cen A was measured. Strangely enough, some of the authors of this paper were also involved in the Messier 33 study ... In any case: 2:1 for the old value of the Hubble constant.
The M 33 study: the paper by Bonanos & al., an OSU Press Release and coverage by ScN, NwS, SC and BdW.
The SZ study: a Chandra Press Release and coverage by Dsc. and ST.
The Cen A study: the paper by Macri & al.

Mars Update

Life traces in meteorite claim 10 years old - and still hardly convincing: SpR, HC, G, AP. Ice geysirs on Mars as an explanation for spots: ASU (more) and JPL Releases, BBC, Cosm., Dsc., NwS, BdW. How the 'spiders' on Mars may form: a paper by Prieto-Ballesteros & al., AstroBiology. MER pictures # 87... 13 and 12, 86... 99, 98 [alt.], 32 and 31 and coverage of Aug. 23: PSB. Aug. 9: SC. Aug. 8: MSNBC, NwS. MRO performs big burn in crucial maneuver to end aerobraking: JPL Releases of Aug. 30 and 25, NwS, SC (earlier). Mars Express releases of Aug. 30 and Aug. 28 and coverage of Aug. 31: Ast. Aug. 30: BdW. Aug. 29: NwS. Aug. 28: SC. Russia, China planning joint Mars mission - Chinese hardware is apparently 'booked' for the Russian Phobos-Grunt mission in 2009: ST. Mariner 4 mystery solved? Science@NASA.

Saturn Update

Cassini pictures # 82... 57, 56, 55, 54, 53, 52, 51, 50, 49, 48, 47, 46, 45, 44, 43, 42, 41, 40, 39, 38 and 37 and coverage of Sep. 1: AB. Aug. 7: NwS.

ISS etc. Update

STS-115 remains on track for a launch on September 6 after a rollback was reversed, while the shuttle successor will be called 'Orion' and built by LockMart. NASA Releases of Aug. 31 (another and another one), 30, 29, 28, 25, 22, 18 (other release), 16 and 7, LockMart, ESA and MPG Releases and coverage of Sep. 1: HC, NwS, RMN, ST. Aug. 31: SN, FT (earlier), NwS, HC, BBC, Dsc., ST. Aug. 30: SN, BBC, NwS. Aug. 29: AW&ST, MosNews, SN (earlier, still earlier, even earlier), SC (other story), ST (earlier). Aug. 28: PSB, SR, SpR, SpN, SN, SC, ST. Aug. 27: SN, BBC, HC, SC, ST. Aug. 26: SN, SC, ST. Aug. 25: SN (loooong preview of STS-115), (earlier, other story), ST. Aug. 24: SN, NwS, ARRL, SC (other story). Aug. 23: FT, HC, BBC (other story), NwS (other and another story), SC (other story), ST, RP. Aug. 22: CS, SC. Aug. 21: HC, FT, NwS (other story), SC, BBC, Fed. Times, ST (other story). Aug. 18: SC, ST. Aug. 17: FT, NwS, ST. Aug. 16: SN, SC. Aug. 15: SN, FT, ST. Aug. 14: SpR (other essay). Aug. 13: SN. Aug. 12: FT, SC. Aug. 11: FT, SC, SD. Aug. 10: Z. Aug. 9: SN, SC. Aug. 7: SN, SC.

Onset of next solar activity cycle observed

There is a new sunspot at high latitude, and indicators of the new cycle were also recorded by the Vector Spectromagnetograph (VSM), one of three instruments making up the Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility: Science@NASA, NSO Press Release, ARRL, NwS, SC.

1000th Kreutz sungrazing comet discovered by SOHO - Polish amateur comet hunter Arkadiusz Kubczak recently discovered his third comet in SOHO LASCO coronagraph images, also the 1000th SOHO comet discovery in the Kreutz group of sungrazing comets: ESA Release.

Unusual & strong meteor outburst predicted for Sep. 1, 2007 - according to a detailled model calculation there should be a rain of bright meteors around 11:37 UTC that day: a mini-paper by Jenniskens in this Nuncius Sidereus (page 1 upper right); SC. The Perseids of 2006: gallery, Gährken.

Five new tiny Milky Way companions

have been discovered in the SDSS, bringing the total of dwarf galaxies to at least 20: a paper by Belokurov & al., NwS.

Dark matter clearly "seen" in galaxy cluster collision where the gas piled up and the DM didn't: Chandra, NASA, UA, and NSF Releases, an APOD and coverage by ScN, Dsc., BBC, Cosmos, NwS, ScA, WP, MrcN, SC, ST, BdW.

Spitzer image of M 42

Despite the nebula's popularity, Spitzer's new image reveals fresh details of M42; the space telescope's Infrared Array Camera collected nearly 10,000 exposures to compose the image: Spitzer, CfA and JPL Releases, Ast., NwS, SC.

E-ELT mirror diameter likely 30 to 42 meters

European astronomers are planning to build an optical telescope that is four times bigger than any in existence; industry studies fathom cost as a function of size: BBC, G. Dome C visions: S&T.

"Lucky Imaging" also in Spain with AstraLux on Calar Alto: Press Release [SR]. SALTICAM delivers: PR, NwS. WIRCam: 1st Light Release.

Hawaii judge reverses permit for more Mauna Kea telescopes - it would have allowed the construction of up to six more telescopes on the summit of Mauna Kea: ENS Newswire, NwS.

'Alma' sets new heights for astronomy - what Chajnantor feels like: BBC.

GLAST Burst Monitor set for spacecraft integration

NASA scientists and engineers have completed final testing and integration of the GLAST Burst Monitor, a space-based instrument for studying gamma ray bursts: MSFC Release, NwS.

MetOp to be launched in October

MetOp, the first in the new European series of operational meteorological satellites in polar orbit, is now scheduled for launch on 7 October 2006: ESA Release.

STEREO launch slips again, to Sep. 18: FT. Earlier: APL, Berkeley, NASA and Uni Kiel Releases, SC, FT, TP.

  • Akaris views of birth and death of stars: JAXA and ESA Releases.
  • HST view of SNR Cas A from 18 ACS pix: STScI and ESA Releases.
  • Voyager 1 at 100 AU from the Sun on Aug. 15: JPL and JHU Releases, PS.
  • Russia, Kazakhstan debate Dnepr crash compensation - Russian officials have promised to pay compensation to Kazakhstan for the crash: ST.

Have you read the the previous issue?!
All other historical issues can be found in the Archive.
Compiled and written by Daniel Fischer