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Space Science

Spitzer Telescope Discovers Planets Via Infrared 113

Posted by Zonk from the earth-like-planet-in-my-sites dept.
DirtyJ writes "Astronomers using the Spitzer Space Telescope have for the first time discovered two extrasoloar planets by directly detecting light from the planets themselves. Usually planets are discovered by indirectly inferring their presence from the wobble of star they orbit, but Spitzer has been able to directly detect these objects at Infrared wavelengths. Nifty conceptual images and videos are available."
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Spitzer Telescope Discovers Planets Via Infrared More

Spitzer Telescope Discovers Planets Via Infrared

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  • Typo (Score:1, Informative)

    by someguy456 ( 607900 )
    the proper term for a planet outside of the Sol solar system is "extrasolar"

    • Re:Typo (Score:1, Funny)

      by Anonymous Coward
      "It's fantastic," said Dr. David Charbonneau of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass., lead author of a separate study on a different planet.

      Wow. They're studying extrasolar planets on other planets. Cool.

    • Re:Typo (Score:3, Insightful)

      by NetFu ( 155538 )
      Go ahead and mod me down, but how can it be "Insightful" to point out "extrasolar" is misspelled, but someone pointing out that the word "asterisk" is misspelled is a Troll?

      I suppose I'll be modded "Redundant" for pointing out what everyone else does -- that Slashdot moderation is ridiculously meaningless...

  • Ob-Infrared-Ditty (Score:4, Funny)

    by Otto ( 17870 ) on Tuesday March 22, 2005 @05:55PM (#12017103) Homepage Journal
    Now the world has gone to bed,
    Darkness won't engulf my head,
    I can see by infrared,
    How I hate the night.

  • Earth First... (Score:3, Funny)

    by RM6f9 ( 825298 ) <rwmurker@yahoo.com> on Tuesday March 22, 2005 @05:55PM (#12017108) Homepage Journal
    We'll strip mine the other planets later?
    If it weren't for the 2-minute delay between posts...

    Just don't feed the trolls (tt)

  • Hot Stuff! (Score:4, Interesting)

    by billstewart ( 78916 ) on Tuesday March 22, 2005 @05:55PM (#12017111) Journal
    Not only did they discover them using infrared, but one really interesting thing about this is that it's the first time that they've directly seen light from one of the planets they discovered, as opposed to previous discoveries which have only seen the light of the star being occluded as the planet passes in front of it. Really nice.
    • Although there is certainly no debate about these two objects being extrasolar planets, it is not the case that they were DISCOVERED using infrared. They were known extrasolar planets that were imaged in the IR using the spitzer telescope. Incidentally, they are not even the first pictures of extrasolar planets, as there is a nice one here [space.com] from September of last year, that was reported on slashdot [slashdot.org].
      • Actually 2M1207 is not a confirmed planetary candidate. While it is around another "star" (a brown dwarf) it seems to fall into the category of brown dwarf as well, making this a binary star system, not a star-planet system.
        • As far as I know (and I have checked the latest update here [obspm.fr], 2M1207b is an extrasolar planet candidate orbiting a brown dwarf, 2M1207a. Although it may be picking nits as to what's a large planet or a tiny star, as brown dwarfs emit light (I believe) from gravitational collapse, not from nuclear fusion as most standard stars do.

    • Uh, that's not how they detect planets (Score:4, Informative)

      by StateOfTheUnion ( 762194 ) on Tuesday March 22, 2005 @07:16PM (#12017905) Homepage
      I don't think that extrasolar planets are detected by occlusion of starlight. I think they are detected by the planet's gravity wobbling the star as the planet orbitx the star and exerts its gravitational pull. There are many sites online about this . . . here's one [mtwilson.edu].

      From the site: There are two basic methods of detecting a planet's gravitational influence on its star:

      * Astrometric Detection

      * Radial Velocity Detection

      The first method - Astrometry - was hinted at in the previous paragraph. We observe a star and measure its position relative to distant background stars (hence the word "metric" in the name). As an orbiting body tugs at its companion star, we observe a change in position of the star. Measurements of a periodic change in position, back and forth, can indicate that something is possibly orbiting the star. Careful analysis of these measurements can tell us about the orbiting object.

      The second method - Radial Velocity - is a completely different kind of measurement, but relies upon the same principle. That is, gravity. As an orbiting body tugs on its companion star, the light from the star will experience a Doppler shift. If the planet pulls the star slightly away from us on Earth, the starlight will be shifted towards longer wavelengths and appear more red; pulled slightly towards Earth, the starlight is shifted towards shorter wavelengths to appear more blue. To accurately measure this Doppler shift, we chose a known spectral line and observe its shift from red to blue and back.

      • I don't think that extrasolar planets are detected by occlusion of starlight. I think they are detected by the planet's gravity wobbling the star as the planet orbitx the star and exerts its gravitational pull.
        They actually use both techniques. This new one now constitutes a third technique.
        • I was looking on the net for a reference to extrasolar planet detection through occlusion of light and I didn't find one. I didn't know that they could do that . . . I would think that the occlusion would be undetectable with current methods. Could you reference the method? I'd be curious to read about an instance of this and the methods used.

          • Here [nasa.gov] is a hokey animation for you to watch. As far as I know, the occlusion method has never actually succeeded at discovering a planet, but it has been used to learn more about planets discovered through other means.
      • Photometry hasn't, AFAIK, been used to detect a planet, but it can tell us about a planet [space.com] once we've found it.

      • I don't think that extrasolar planets are detected by occlusion of starlight.

        In fact... They are. (IIRC it was one of the first methods proposed to search for extrasolar planets, because brightness can easily be measured, while precise angular position is a Hard Problem.)

        Google on planet detection by occultation [google.com]. Also, this links page [nasa.gov] has numerous links, and is part of the website for the NASA Kepler [nasa.gov] mission. (A probe designed to search for extrasolar planets via occultation.)

        • precise angular position is a Hard Problem.

          True, but not always relevant. You don't have to look for lateral motion to detect a gravitational influence. Radial motion, detectable by Doppler shifts in spectral features, is also usable. Although not entirely trivial and not applicable to all stars, it has been used very successfully to find "invisible" companions. Indeed, spectroscopic binary stars have been known for well over a century.

          Paul

      • This German article [heise.de] lists a number of ways to detect planets. In addition the two you mentioned, they have the Pulsar-Timing-Method which can of course only find planets around Pulsars [psu.edu], Gravitational Microlensing [nd.edu], and the Transit-Timing-Method [arxiv.org]. And occlusion of starlight IS an important way to find planets.

        Of course, you can always check this site [obspm.fr] for all extra-solar planets found, and method they were found with.

      • Yeah, I realized that one after I'd posted. Most extrasolar planets have been detected by the gravity effects rather than occlusion, but at least one of the articles did refer to a small number being detected by occlusion as well.
    • Actually that's just one class of techniques that's been used prior to this. The gravitational disturbance of the parent star (wobble in the star) has been used too.

  • not discovered, but observed (Score:5, Informative)

    by heidi ( 82179 ) on Tuesday March 22, 2005 @05:56PM (#12017116)
    the planets are not newly discovered. they were previously known, but not directly imaged before.

    • Pschaw! (Score:1, Troll)

      by LokieLizzy ( 858962 )
      Anyone can discover (or "observe") a planet. Call me when we discover (or "observe") some intelligence on one.

      On second thought, maybe we should start with planet Earth.

    • the planets are not newly discovered. they were previously known, but not directly imaged before.

      Yes, they were were Xenu came from and the Co$ will be suing to remove this information from internet servers because it constitutes a violation of their copyrighted duh trade secrets.

    • So what about names? (Score:3, Interesting)

      by serutan ( 259622 )
      Has anybody started arguing over what/how to name these extrasolar planets? They probably have cryptic alphanumerical designations like other celestial bodies, but I wonder if anyone has proposed any planet names?
      • We've already found 145 extrasolar planets, and naming them is going to be a problem. We have only a finite supply of mythological names, and a lot of them are already taken. I'm sure someone, somewhere, is actually being paid by NASA and/or the ESA to think about this, and I have no inside knowledge of that process, but I would assume that plabets are going to be named after the stars they orbit wherever possible. If the star has no name, maybe they'll use the name of the constellation it is in as a bas
    • Unfortunately, they were not imaged, but deduced from the reduction in (IR) light when hidden behind the associated suns.

      IR is at a disadvantage for actual imaging compared to visible light, due to the longer wavelength making diffraction worse. IR's advantage is that the planets are radiating (or reflecting) more in IR than visible.

  • And they call this science? (Score:5, Funny)

    by Mindwarp ( 15738 ) on Tuesday March 22, 2005 @05:58PM (#12017131) Homepage Journal
    If I were providing the conceptual images I would DEFINITELY have included more orbiting alien Death-Stars. Honestly, these conceptual artists have no imaginations!

  • Spitzer (Score:5, Informative)

    by someguy456 ( 607900 ) <someguy456@phreaker.net> on Tuesday March 22, 2005 @06:00PM (#12017152) Homepage Journal

    Is anyone else interested in the techical specifications of the Spitzer? I hadn't heard of it till today...

    from About Spitzer [caltech.edu]

    The Spitzer Space Telescope (formerly SIRTF, the Space Infrared Telescope Facility) was launched into space by a Delta rocket from Cape Canaveral, Florida on 25 August 2003. During its 2.5-year mission, Spitzer will obtain images and spectra by detecting the infrared energy, or heat, radiated by objects in space between wavelengths of 3 and 180 microns (1 micron is one-millionth of a meter). Most of this infrared radiation is blocked by the Earth's atmosphere and cannot be observed from the ground. Consisting of a 0.85-meter telescope and three cryogenically-cooled science instruments, Spitzer is the largest infrared telescope ever launched into space

    • Re:Spitzer (Score:4, Informative)

      by astrobabe ( 533099 ) on Tuesday March 22, 2005 @06:31PM (#12017455) Homepage
      As someone who works who runs the Spitzer Helpdesk-

      Thank you for reading the documentation!

      And I'm a bit dissappointed people still haven't heard of us.

      We launched in August 2003 and have been in science operations since December 2003. We have an approximately 5 year operational life time though the IRAC instrument may still be useable with only passive cooling once we run out of cryogen.
      • As someone who works who runs the Spitzer Helpdesk

        Does he call for help often? :-)

        I would assume that most of Slashdot's population knew about Spitzer. I did.

    • I thought Adaptive Optics (AO) enabled us to build that sort of IR telescope right here on Earth and save the launch costs.

  • article is DUI on the actual technique (Score:5, Informative)

    by OneOver137 ( 674481 ) on Tuesday March 22, 2005 @06:03PM (#12017187) Journal
    While they did discover them using IR, the technique was looking at eclipse intensity depth rather than direct observation. Good stuff though!

  • Planet "X" (Score:4, Interesting)

    by H_Fisher ( 808597 ) <[h_v_fisher] [at] [yahoo.com]> on Tuesday March 22, 2005 @06:03PM (#12017193)
    If this concept works in the long run, I wonder how (if at all) it might be used to find the "tenth planet" that some scientists think might be orbiting beyond Pluto [spacetoday.org]?

    If and when the Hubble is updated, could this type of gear be added, or orbited in tandem, to allow both visual and infared examination of space? (IANA astronaut, so if this sounds stupid...)

    • Re:Planet "X" (Score:1, Interesting)

      by Anonymous Coward
      For those that even consider Pluto a planet and not just a very big KBO...

      Reason why Pluto shouldn't be called a planet.
      1) Orbit lies outside the planet the other planets orbit in.
      2) It's smaller then many moon.
      3) Many large asteroids also have moons.
      4) Other large KBO's, like Pluto, are in orbital resonance with Neptune.

      Reasons to keep Pluto a planet.
      1) Don't have to reprint text books, thus US schools can keep using ones that state 'Someday, man may walk on the moon'/
      2) It was discovered by an American!
      • 1) Don't have to reprint text books, thus US schools can keep using ones that state 'Someday, man may walk on the moon'/
        2) It was discovered by an American!

        Mmmmm.... Is that the fresh smell of bitterness in the air?
      • " It was discovered by an American!"
        It is biggest reason - American nationalism. Scientific objectivity, anyone?
    • If this concept works in the long run, I wonder how (if at all) it might be used to find the "tenth planet" that some scientists think might be orbiting beyond Pluto?

      It already was - with negative results. Here's a quote [scholastic.com]:

      When a new NASA satellite called IRAS was launched, we hoped that it could be used to find Planet X. IRAS looks at the sky in the infrared, which would make finding another planet much easier, and it could also find very faint things. People looked very hard (everyone wanted to be the
    • No Hubble wouldn't work.

      Any possible planet X would be far enough away that:

      1) it couldn't reflect much solar incident light, hence would be pratically invisible in the optical

      2) for a thermal measurement you'd need the mid IR which you cannot do with Hubble as contamination from Earth is too high and Hubble is not actively cooled. To get a mid IR instrument on there with usable data you would have to cool the entire telescope assembly as we do with Spitzer.

    • Re:Planet "X" (Score:3, Informative)

      by CanSpice ( 300894 )
      If and when the Hubble is updated, could this type of gear be added, or orbited in tandem, to allow both visual and infared examination of space?


      The Hubble Space Telescope already has infrared capabilities, just not at the longer wavelengths that Spitzer can do. The Near Infrared Camera and Multi-Object Spectrometer (NICMOS) is an instrument on HST, and it can go as long as 2.5 microns, whereas Spitzer observes from roughly 3 to 180 microns.
      • Correction: NICMOS could go as long as 2.5 microns. It hasn't been working for ~6 months now. And, if SM4 never goes up, it won't work again.

  • How about... (Score:1, Interesting)

    by Anonymous Coward
    ...the ACTUAL infrared picture, instead of just an artist's rendition. They took at least one IR pic, let's see it.
    • Actually, they didn't take a conventional "picture" of the planet, just photometric observations. I don't know if Spitzer could ever resolve (i.e. map onto different pixels) the light from the star and that from the planet when at maximum separation, but surely it's impossible in the observed position, with the planet being occultated behind the star. Actually, the ideal conditions for this photometric approach (measuring the "missing light" when the planet disappears) are the worst possible for direct imag
      • Just to throw in some numbers on your first point, yes, Spitzer doesn't have a chance of splitting HD 209458 and its planet (cleverly named HD 209458b) into two objects on the detector. HD 209458 is a star 50 parsecs away, and the semi-major axis of the planet's orbit is 0.05 AU, translating to about 1 milli-arcsecond of separation or so (that's the size of a penny seen from 4000 km away, for reference).

        To see that in the mid-infrared (10 microns, say), you'd need a telescope about 2 km across. Best we'r

  • The thrill of discovery (Score:4, Insightful)

    by Webmoth ( 75878 ) on Tuesday March 22, 2005 @06:08PM (#12017238) Homepage
    In an age when scientists attempt to prove what they already believe, it's nice to know that there are still some who practice science for the sake of discovery:

    "We're back to square one," said Dr. Sara Seager, Carnegie Institution of Washington, Washington, co-author of the Deming paper. "For us theorists, that's fun."

    Ah, if we could all enter into an investigation with a blank slate free of preconceived notions, there's no telling what we'll find.

  • IR temperature reading? (Score:3, Interesting)

    by RealUlli ( 1365 ) on Tuesday March 22, 2005 @06:15PM (#12017307) Homepage
    From the article:

    The Spitzer data told the astronomers that both planets are at least a steaming 1,000 Kelvin (727 degrees Celsius, 1340 Fahrenheit). These measurements confirm that hot Jupiters are indeed hot.

    I wonder, what would be the reading someone would get from outside our atmosphere by looking at overcast sitting in the sunlight?

    Clouds are pretty good reflectors of visible as well as infrared light, afaik, so they should appear to be pretty hot...

    Regards, Ulli

    • Re:IR temperature reading? (Score:5, Interesting)

      by astrobabe ( 533099 ) on Tuesday March 22, 2005 @06:27PM (#12017414) Homepage
      While clouds are significants sources of albedo, the Earth would still not appear very "hot" as our atmosphere is general is quite cool. A planned instrument for a Mars orbiter will likely contain a spectrograph which will be used to look back at Earth to give astrobiologists an idea what the atmospheres of extrasolar planets with life may look like from a distance.
    • Although IANAP (I Am Not A Planetologist), I believe that, in order to emit in the infrared, a substance has to absorb heat first. The light coming from the sun is reflected from the cloudtops, true, but this is not the same as emitting in the infrared. A blacktop road would emit plenty of infrared after a sunny day because the substance of the blacktop was able to absorb some of the energy of the sunlight. Contrast that with a mirror which, if placed in direct sunlight, would reflect much more light tha

    • Re:IR temperature reading? (Score:1, Informative)

      by Anonymous Coward
      Using infrared satellite imagery, cloud tops on Earth show up generally between -20 and -80 C, with higher cloud tops meaning colder temperatures.
  • Dibs on being the guy who steps on them first!

  • Further info on Spitzer and the extrasolar planets (Score:5, Informative)

    by astrobabe ( 533099 ) on Tuesday March 22, 2005 @06:21PM (#12017361) Homepage
    Yes Spitzer has been in science operations for over a year now. These detections were made with the two imagers- IRAC and MIPS. IRAC is the shorter wavelength camera (the observations were done at 8 microns) and MIPS the longer wavelength camera (observations done at 24 microns). Both planets are approximate 1000 degrees Kelvin and are Jupiter class with respect to mass.HD 209458b is 0.68 times the mass of Jupiter and has a radius about 1.35 times Jupiter's. The second planet- TrES1 has a mass equal to 0.76 Jupiter masses and is 1.04 times the radius of Jupiter. (and I do work for Spitzer and knew about these discoveries about 2 months ago when they first came into our Helpdesk which i run)

  • The ACTUAL DATA (Score:4, Interesting)

    by cinnamon colbert ( 732724 ) on Tuesday March 22, 2005 @06:57PM (#12017734) Journal
    don't look entirely convincing, espcially in the second case

    http://www.spitzer.caltech.edu/Media/releases/ss c2 005-09/ssc2005-09a.shtml

    did anyone see how they discount things like solar flares

  • In other news..... (Score:2, Funny)

    by Anonymous Coward
    The inhabitants of a distant galaxy are complaining that their TVs keep changing channel for no apparent reason.
  • Couldn't a similar method be applied to detect unnatural light? Say... an alien NYC? It could greatly increase our efforts in finding intellegent life outside of our own. At least smart enough to make a lightbulb.
  • While the achievement of the Spitzer IR space telescope is impressive, a project now in development called the Terrestrial Planet Finder will sport many times the resolution of Spitzer and could become the first telescope to see an Earth-sized planet orbiting around another star.

    Essentially four telescopes with 3.5-meter mirrors operating in space in a synchronized fashion, TPF is designed to look for Earth-sized planets orbiting other stars circa 50-100 light years from Earth. If TPF finds a Earth-like pl

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