planet detection

[mattster]

i know that the current way of detecting planets in other solar systems isnt going to give us nice full colour hi res photos, but with the best land or space telescope is it possible to see directly any planets around alpha centurai or is that still too far away? if so how far away is telescope technology from being able to see them?

 

[MeteorWayne]

At this time it is not possible to directly image a planat around any other star.<br />For one reason, they are too small, a telescope would need to be quite large.<br />And the brightness of the star overwhelms that of the nearby planet.<br /><br />Space telescopes are under development that MAY permit some direct images in a few decades. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[deapfreeze]

I can't wait for some cool photos of planets from new telescopes. I hope they are strong enough. <div class="Discussion_UserSignature"> <p><font size="2" color="#0000ff"><em>William ( deapfreeze ) Hooper</em></font></p><p><font size="1">http://deapfreeze-amateur-astronomy.tk/</font></p><p> </p> </div>

 

[alokmohan]

Whether an exoplanet exists?There may be other explanations.They should be eliminated.

 

[dragon04]

It will be a pretty tough task. Take Hubble for example. As great a telescope as it is, images of Pluto as seen through it are very fuzzy and don't show much detail at all. And Pluto is in our own solar system, not 4 or so light years away.<br /><br />While certainly no more than a layperson, with the current state of optic technology, even a space based telescope with hundreds of mirrors the size of Hubble's might not do the trick, I'd think.<br /><br />Even if such a telescope <b>could</b> resolve extrasolar planets and give is images like Hubble does of, say Saturn (let alone a tiny terrestrial rock like our Earth), imagine the cost and the <b>time</b> of building and deploying such a beast!<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[MeteorWayne]

Like this: <br /><br />And this is not a single image, this is based on data over a period of rotatation added together <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[MeteorWayne]

Here's a better example of the single shot capability.<br /><br />Pluto is 0.00048 LY away <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[dragon04]

Thank you for illustrating my point. Always good to know I can count on guys like you! <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[derekmcd]

I would imagine the lengthy exposure times required to collect the light make focusing on closer objects more difficult. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

I doubt it. Besides, for Pluto at Mag 13.7 it's plenty bright enough. It's just very small!<br /><br />Look at the pictures if the hubble deep field that took hours of time to photograph. Pretty darn clear!!<br /><br />Here's another from 1994. <br /><br />This is the clearest view yet of the distant planet Pluto and its moon, Charon, as revealed by NASA's Hubble Space Telescope (HST). The image was taken by the European Space Agency's Faint Object Camera on February 21, 1994 when the planet was 2.6 billion miles (4.4 billion kilometers) from Earth; or nearly 30 times the separation between Earth and the sun.<br /><br />Hubble's corrected optics show the two objects as clearly separate and sharp disks. This now allows astronomers to measure directly (to within about 1 percent) Pluto's diameter of 1440 miles (2320 kilometers) and Charon's diameter of 790 miles (1270 kilometers). The Hubble observations show that Charon is bluer than Pluto. This means that both worlds have different surface composition and structure. A bright highlight on Pluto suggests it has a smoothly reflecting surface layer.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

I don't much about telescopes. My thought being that since Hubble can take such amazing picture at distances billions of light years out, why should it not be able to take an absolute crystal clear photo of Pluto? As with any camera, the longer the exposure, the more prone you are to see movement which blurs the photo. The closer the object, the more movement can be detected, hench shorter exposure times. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[MeteorWayne]

It tracks the movement of objects it's imaging. Besides, as I said it's a very short (relatively speaking) exposure, though I was unable to find the exact exposure time. Still searching for that. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[dragon04]

Not that I can provide a definitive answer, but I would imagine that it has something to do with the optics (like telescopes better suited for planetary viewing as opposed to deep-sky) as well as the fact that galaxies are gigantic light emitting structures and Pluto is a tiny light <b>reflecting</b> one. <br /><br />IOW, Hubble's stock in trade is resolving huge, bright things relative to their magnitude and distance from it. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[MeteorWayne]

Seems to work fine here <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[derekmcd]

Indeed it does. Beautiful image.<br /><br />Have done a bit of reading, I have realized there is a difference between the ability to gather light and resolution. Hubble might not be very good at detailing small objects, but it is certainly unparalleled at picking up the light from those objects. <div class="Discussion_UserSignature"> <div> </div><br /><div><span style="color:#0000ff" class="Apple-style-span">"If something's hard to do, then it's not worth doing." - Homer Simpson</span></div> </div>

 

[dragon04]

For sure it does. But Jupiter is a relatively close, relatively large body.<br /><br />I'm certainly not criticizing Hubble. I was more addressing the issue of why Hubble doesn't resolve Pluto better than NGCpickanumber.<br /><br />Stick Jupiter where Pluto is. Not 500 or so million miles from Earth, but billions of miles. I'd think the pictures wouldn't be nearly as awesome, right?<br /><br />Those structures on distant galaxies that Hubble images are tens of thousands of light years in length. How many Hubbles would it take to resolve a single G class star in one of the Galaxies of the Virgo Cluster, for example?<br /><br />Sorry if you got the idea that I don't think Hubble is anything but a modern technological miracle. Not at all what I was getting at. <div class="Discussion_UserSignature"> <em>"2012.. Year of the Dragon!! Get on the Dragon Wagon!".</em> </div>

 

[MeteorWayne]

The point you (?) made earlier is good. It's better at light gathering than resolution because it has a fairly small mirror. And it's light gathering is not so much because of aperture, but because it can take really long exposures, through a (near) vaccuum. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[alokmohan]

Confirm if it is correct.

 

[MeteorWayne]

Huh? <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[nexium]

Perhaps I can clarify for Al. The light gathering of a telescope mirror is directly proportional to the area of the mirror and the exposure time. Hubble gives better results for very long exposuers than ground based telescopes. The vacuum of space helps. Aperature means much the same thing as mirror size. Resolution is mostly quality of the optics and the lack of jitter in the telescope tracking, but a big mirror helps. High magnification is needed and/or a very large number of CCD = charge coupled cells to resolve objects that have a diameter of less than one arc second. Please embellish, refute and/or comment. Most telesopes are optimized for light gathering rather than high magnification and detailes smaller than one arc second. In theory both are possible if not practical. Neil

 

[alokmohan]

Thanks.

 

[MeteorWayne]

Working off what you said..<br />Magnification is limited from the earth's surface due to atmospheric distortion, which is why adaptive optices were developed. That has helped a lot, allowing large scopes to match (and in some cases exceed) the resolution of the much smaller Hubble mirror.<br />Resolution is directly proportional to the diameter (or in the case of multiple scopes or interferometers, the distance between them). CCD density is a linear muliplier.<br />Since the hubble has no atmospheric limitations, and can observe for long periods (adding frames on from multiple orbits as well) it can do both these things very well, for it's size.<br />But it isn't a very big scope <img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[qso1]

alokmohan:<br />Whether an exoplanet exists?There may be other explanations.They should be eliminated.<br /><br />Me:<br />You bring up a good point and I'll try to explain what is actually happening as best I can. When astronomers start looking at a candidate star for exoplanets, they look withing the limits of the detection technology and look relatively close to the parent star.<br /><br />Hot Jupiters as many exoworlds became known were detected this way. They have short orbital periods so one does not have to spend half a life looking at something repeat every 12 years (As Jupiter would do if observed from afar).<br /><br />51 Pegasi for example, 4 day orbital period IIRC. A matter of several weeks of observation should be enough to rule out any other explanation when radial velocity is the technique being utilized. In fact, years ago, I recall an astronomer named Gray disputing the 51 Pegasi observations. Later however, he apparently did his own research and came to the same conclusion as the original discoverers. The original discoverers had already explained the steps they took to eliminate other possibilities for their measurements and any exoplanet astronomer probably knows the well worn tale of Van De Kamp and Barnards star.<br /><br />Then there is transit photometry.<br /><br />A method by which starlight is measured for any regular interval drops in light output. Small percentage drops to be sure, but within current detection methods. A star could have a drop in measurable light output resulting from star spots but star spots do not occur at regular intervals. When measured drops are recorded at regular intervals, one can safely assume its a planet. Of course, there is the outside possibility of it being something else but what that would be is not yet known.<br /><br />I like to think of it this way. I don't know with 100% certainty if astronomers are really detecting planets...but factoring in the normal process of science first, as illustrated by the Gray episode <div class="Discussion_UserSignature"> <p><strong>My borrowed quote for the time being:</strong></p><p><em>There are three kinds of people in life. Those who make it happen, those who watch it happen...and those who do not know what happened.</em></p> </div>

 

[alokmohan]

Agreed .How do you know if something is a brown dwarf or not?Thy may have boder line cases.

 

[3488]

Hi there.<br /><br />I have severe doubts about many of the radial velocity findings, until they can be confirmed <br />by space based observatories.<br /><br />The Earth is far too unstable a platform & even with adaptive optics, atmospheric aberration <br />will still give false readings.<br /><br />IIRC 51 Pegasi & many others have since been found<br />to be genuine from space based observations.<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>