Jump to content

johnme

Μέλη
  • Αναρτήσεις

    7
  • Εντάχθηκε

  • Τελευταία επίσκεψη

    Ποτέ

του/της johnme Επιτεύγματα

Rookie

Rookie (2/14)

  • Conversation Starter
  • First Post

Recent Badges

0

Φήμη

  1. johnme

    AstroSurfing

    Ένα καινούργιο ελληνικό site με όλα τα πρόσφατα Αστρονομικά Νέα είναι γεγονός. Επισκεφθείτε το προσωρινά στην παρακάτω διεύθυνση: http://students.ceid.upatras.gr/~antonell/
  2. yparxei ena site sth dieyuynsh www.lightandmatter.com opoy mporeis na katebaseis dorean ena biblio me themata astrofisikis. sthn selida ayth yparxoyn kai alla diathesima biblia fisikis.to sygkekrimeno einai to book6.
  3. Επειδή συμμετείχα και εγώ στον διαγωνισμό θα ήθελα να ρωτήσω αν κάποιος ξέρει πότε και πώς θα ανακοινωθουν οι νικητές.Ένα e-mail που έλαβα από τον υπεύθυνο έλεγε πως η διόρθωση θα τελειώσει κατά τις 24 Απριλίου ενώ η ηλεκτρονική διεύθυνση της Αστρονομικής Εταιρείας Βόλου που διοργάνωνε τον διαγωνισμό έχει να ανανεωθεί από το 1999.
  4. Συμφωνώ και εγώ με αυτά, όμως νομίζω πως αυτή η ίδια η εκλαίκευση της επιστήμης και η σύνδεση στο μυαλό κάποιων επιστημόνων ενός θεωρητικού κατασκευάσματος με μία πραγματική εικόνα έχει βοηθήσει πολλές φορές την έρευνα ιδιάιτερα σε τομείς όπου δεν έχει προχωρήσει αρκετά η επιστημονική έρευνα. Αυτό βέβαια εξαρτάται από το αντικείμενο μελέτης και τον βαθμό σύνδεσης και αλληλεξάρτησης αυτού με τον υπόλοιπο μακρόκοσμο.Για να γίνω πιο σαφής, είναι σίγουρο και κανείς δεν θα μπορούσε να το αμφισβητήσει, πως η εικόνα που πρέπει να έχει για το σύμπαν ένας ερευνητής της NASA ο οποίος μελετά τις τροχιές κάποιων διαστημικών βολίδων είτε αυτές πρόκειται να μελετήσουν αντικείμενα του ηλιακού μας συστήματος μας είτε άλλα, δεν διαφέρει καθόλου από αυτήν ενός μέσου ανθρώπου με γνώσεις Λυκείου ή και Πανεπιστημίου.Το γεγονός αυτό άλλωστε διευκολύνει σε μεγάλο βαθμό την έρευνά του αφού δεν είναι υποχρεωμένος να δαπανήσει ώρες ατέλειωτες μελετώντας σύγρονα θέματα Κοσμολογίας σε βάρος της ουσιαστικής του έρευνας. Ας πάρουμε για παράδειγμα τον Νεύτωνα ο οποίος αποτελεί ουσιαστικά τον θεμελιωτή της επιστημονικής έρευνας.Αυτός, αδιαφορώντας (είτε επειδή δεν τον ενδιέφερε είτε επειδή δεν μπορούσε να ασχοληθεί με τέτοια θέματα) για το λόγο εμφάνισης συγκεκριμένων ιδιοτήτων από την ύλη,αρκέστηκε στο να δεχθεί a priori αυτές τις ιδιότητες και να προσπαθήσει, δημιουργώντας το απαραίτητο φυσικό αλλά και μαθηματικό υπόβαθρο να ερμηνεύσει τα διάφορα φυσικά φαινόμενα. Το γεγόνος αυτό βέβαια δεν θα πρέπει συμβαίνει σε περιοχές της επιστήμης όπου δεν μπορούν να γίνουν προεκβολές στο συνήθη κόσμο αφού δεν υπάρχουν σε αυτόν τα αντίστοιχα μηχανικά συστήματα(όπως συμβαίνει με κάποιες έννοιες της Κβαντικής Φυσικής-spin κ.α.).Σε αυτήν την περίπτωση είναι σίγουρη η αποτυχία της έρευνας αφού πολλές λεπτομέρειες ίσως περάσουν απαρατήρητες. Πολλές φορές λοιπόν ίσως αυτή η δυνατότητα των εννοιών της Κοσμολογιάς,όπως το σύμπαν,να ανάγονται σε άλλες εκλαικευμένες δεν καθιστούν την επιστήμη απατηλή αλλά μάλλον προσαρμοζόμενη στο επίπεδο μελέτης της ύλης. Δεκτές ενστάσεις και/ή συμπληρώσεις!! Γιάννης
  5. johnme

    nees plirofories gia ta ifaisteia tis Io

    Contact: Guy Webster/JPL (818) 354-6278 Lori Stiles/University of Arizona (520) 626-4402 IMAGE ADVISORY March 29, 2001 TWO SPACECRAFT WATCH A TOWERING INFERNO ON IO Two NASA spacecraft jointly observing Jupiter's moon Io this winter captured images of a towering volcanic plume never seen before and a bright red ring of fresh surface deposits surrounding its source. Combined information from images taken by the Cassini and Galileo spacecraft indicates the new plume is about the same size -- nearly 400 kilometers or 250 miles high -- as a long-lived plume from Io's Pele volcano. Pele's plume and ring are also seen in the new images. The images and further information about them are available online from NASA's Jet Propulsion Laboratory, Pasadena, Calif., at http://www.jpl.nasa.gov/pictures/jovianmoons , from the web sites of the Cassini Imaging Science team at the University of Arizona, Tucson, at http://ciclops.lpl.arizona.edu/ and from the University of Arizona's Planetary Image Research Laboratory, at http://pirlwww.lpl.arizona.edu/Galileo/Releases/ . The new plume originates from a volcanic feature named Tvashtar Catena near Io's north pole. Scientists were astounded to discover so large a plume so near the pole, because all active plumes previously detected on Io have been over equatorial regions and no others have approached Pele's in size, said University of Arizona planetary scientist Dr. Alfred McEwen. Galileo might pass right through the Tvashtar plume in August, if the plume persists until then. The spacecraft will be flying over that part of Io at an altitude of 200 kilometers (124 miles). Material in the plume is tenuous enough to present little risk to the spacecraft, and passing through it could give an opportunity to analyze the makeup of the plume, said Dr. Torrence Johnson, Galileo project scientist at JPL. Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages Cassini and Galileo for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology in Pasadena.
  6. johnme

    ΔΙΑΣΤΗΜΑ

    Μόλισ χθες έλαβα κάποιες νέεσ πληροφορίεσ που αφορούν την εξέλιφη του προγράμματος Cassini.Παραθέτω ατόφιες τις ανακοινώσεις της NASA. New measurements from NASA's Cassini spacecraft indicate that any future spacecraft venturing very near Jupiter would be zapped by the radiation belts there even more severely than had been previously estimated. The harshest radiation is within about 300,000 kilometers (about 200,000 miles) of the giant planet. NASA's Galileo has been orbiting farther out than that, and Cassini was nearly 10 million kilometers (6 million miles) from Jupiter when it passed by three months ago on its way to Saturn. Both of those craft have especially durable electronics hardened to withstand radiation. Cassini's Italian-made main antenna, which serves for communicating with Earth and will later be used to radar-map Saturn's moon Titan, was used during the Jupiter flyby in a listen-only mode, pointed toward Jupiter. It caught details of the radiation belts' natural radio emissions not discernible from Earth or any earlier spacecraft, said Dr. Michael Janssen, team leader for the radiometer instrument. The quality of results is encouraging for radar research at Saturn, he said. "We got some surprises," said Dr. Scott Bolton, a physicist for NASA's Jet Propulsion Laboratory, Pasadena, Calif. "This has implications not only for understanding the physical processes in the radiation belts, but also for designing any spacecraft for future exploration close to Jupiter." Preliminary results from these radio-science investigations were presented today at meetings of the European Geophysical Society in Nice, France. High-energy electrons, traveling at nearly the speed of light in spirals shaped by the magnetic field enveloping Jupiter, beam out radio emissions called synchrotron radiation. Synchrotron radiation is not the type that could damage spacecraft, but it provides information about the high- energy electrons emitting it, which are the potential hazards. Earth-based radio telescopes have mapped some wavelengths of synchrotron emissions from Jupiter's radiation belts, and scientists have used that information to model the belts and estimate their potential to damage spacecraft. But the shortest wavelengths, emitted only by the highest-energy electrons in the belts, get lost in hundred-fold stronger, non-synchrotron radio emissions from heat in Jupiter's atmosphere. As it flew past Jupiter, Cassini had a better angle for distinguishing atmospheric emissions from radiation belt emissions, though the task was still challenging. The craft had to rock back and forth to scan across the target area several times, then roll 90 degrees and scan back and forth again, to recognize the synchrotron radiation by its trait of polarization. "Using its antenna, Cassini has been able to anchor the high-energy end of the electron spectrum from Jupiter's radiation belts for the first time," Bolton said. New measurements made from Earth of Jupiter's radio emissions added context for interpreting the Cassini radiometric measurements. Scientists took readings at several wavelengths using the National Science Foundation's Very Large Array of radio telescopes near Socorro, N.M. And students at 25 middle schools and high schools in 13 states used a large dish antenna near Barstow, Calif., by remote control from their classrooms to monitor changes in Jupiter's emissions from week to week. The students' work, coordinated by a partnership of JPL's Deep Space Network and the Lewis Center for Educational Research, Apple Valley, Calif., helped rule out the possibility that Cassini's measurements happened to be made when emission levels were either unusually high or unusually low. Cassini's measurements indicate that the highest-energy electrons are sparser than anticipated. That's not good news for spacecraft designers, though. Accounting for the known levels of longer-wavelength synchrotron radiation without having as many of the highest-energy electrons as expected means estimates must be increased sharply for the number of electrons with slightly lower energy levels. Those electrons are still plenty energetic enough to fry electronic equipment. The increase in their numbers is many times greater than the decrease in numbers of highest-energy electrons, compared to the earlier estimates, so the net result is a more hazardous environment than previously estimated, Bolton said. No approved NASA missions now in development would venture as close to Jupiter as the region with the heightened estimates of radiation hazard, said Bolton. The moon Europa, target of NASA's next planned mission to the jovian system, is about twice as far from the planet. Europa is nevertheless in a hazardous-enough radiation environment that the Europa Orbiter mission is being designed with substantial shielding and durable electronics. The new measurements by Cassini carry direct implications for potential closer-in exploration, such as NASA Discovery mission proposals for orbital studies of Jupiter's atmosphere and internal structure. The only spacecraft that have experienced the full blast of the radiation belts so far have passed through them quickly. NASA's Pioneer 10 and 11 each sped close to Jupiter during flybys in the 1970s. Galileo's atmospheric probe shot through the belts on Dec. 7, 1995, before plunging into Jupiter's atmosphere. The Galileo orbiter briefly passed close to Jupiter that same day to begin its first orbit. The orbiter will end its tour with a dive into the atmosphere in 2003. Galileo has already endured more than three times the radiation exposure it was built to withstand. The recent radio observations help with understanding how Jupiter's radiation belts work, as well as what hazards they present, Bolton said. "We would like to know more about their potential interactions with the atmosphere and with the rings," he said. Jupiter's radiation belts provide a useful comparison for better understanding of Earth's radiation belts, too. images/smiles/icon_smile.gif
  7. tha ithela na ekfraso kapoies enstaseis moy gia ta themata toy diagonismou kai genika gia tin diorganosi. Katarxas sto sxoleio mou sthn Patra den mas eixan enhmerosei.Anagkastika na bro monos mou ta tilefona Oson afora tora ta themata pisteyo pos an skopos toy diagonismou einai h proothisi tis astronomias den tha eixan tethei dio oloklhra themata pou aforousan tis apostoles tis NASA sto diasthma.Pisteyo pos tha htan protimotero na eixan erotithi oi diagonizomenoi gia alla pio endiaferonta themata astronomias,astrofysikis,radioastronomias. Parallila den pisteyo pos tha eprepe oi dyo nikites toy diagonismoy na min mpoei na einai toy idioy filou.
×
×
  • Δημιουργία νέου...

Σημαντικές πληροφορίες

Όροι χρήσης