How do you fix ghost images on a telescope?

I have a refractor telescope, and any time I look through it I see the main image, with two ghost images in line with it. How can I fix that?

Question by mhippo   |  last reply


I keep seeing DIY plans for "Burning Lasers" are these the same as the red or green Lasers used to point into the night sky at selected stars,planets etc?? Can anyone direct me to info on this type of Laser?  I don't want to burn anything. Just a very strong beam that will point out objects in the night sky.                 Thanks

Question by aristos   |  last reply

What is the axial orientation of Polaris with respect to the Earth? Answered

So... I know the Earth's axis of rotation currently points (roughly) at Polaris, the North Star. (which, of course, is why we can navigate by it here on Terra Firma).  I also know that Polaris is about ~500 ly from us,  has a rotational period (hence an axis), that it's a transitional Cepheid (sp) (a star that varies between a larger, brighter state and a smaller, denser one) , that it has at least two l known, low-output companion stars, and that since the ~1940s it has undergone visible changes in its rotational period and its output. My excuse and reason  for asking... First, I did google it. Either no one has asked the question(doubtful), it can't really be determined with our present level of science (could be, idk), or I just didn't use the right search  terms to find the answer (the usual culprit ime) , but in any case, after an off and on search that's spanned the past ~year, I think it's time I ask. Secondly, the inspiration. I enjoy amateur astronomy.  However, time and equipment and location often limit my grand delusions for the next "Citizen challenges Hubble with stunning new photo of Zeta p3044-a!" award hahahaha.  But the real problem is most often because of my mid-level scope's somewhat limited ability (in comparison to a German equatorial mount) to track consistently and smoothly, and as a result, Polaris becomes an easy target when I get frustrated with the scopes performance on a given night (sometimes it does track brilliantly... for a stepper-driven alt-z, but only sometimes and even then only to the limits of the steps) because the only thing the scope has to track when pointed at the North Star is rotation, which it seems to handle better than both directions of movement (probably needs a new gear or the motor is wearing or my expectations are simply higher than that of my equipment ...). Of course, I also quite often choose to shoot Polaris when conditions are such that it's the only viable target (for instance, when I'm stuck imaging from my backyard, I have a postage stamp size hole that happens to point at Polaris... which of course basically "doesn't move", pretty much everything else is shrouded by century old, 8-100 ft tall forest during the warmer months, and when I can't drive out to a more suitable location, it's a lucky night when everything is "right", I can even align the mount (it uses a goto controller that requires a 3 star alignment for tracking with any accuracy). So Polaris is a no-brainer, (take some images for arts sake, fine tune the in-situ collimation, data-reduction test sets, etc.) . Either that or do something else...  Anyway, as a result of all of this, I'm found myself enjoying the simplicity of shooting the North Star and the area around it, and having fun with image processing and even optical train modifications to further the artistic side. And I've read a few articles about it's variability and the ~relatively significant changes in its behavior that have been occurring during the past 50 years that got me to thinking What I'm wondering is that when I image Polaris, am I looking at it "on its side?", "on axis?", or at some other viewing angle? Not that I'm going to be able to literally "view it on its side" or something, since optically imaging the star beyond that roughly of a point-source isn't practical, but just to know, since the darned question won't get out of my head. (been asking it for the past year quietly to myself and google. I hate to think how many cumulative hours I've spent at it...) thanks!

Question by seandogue   |  last reply

How do I build a reflecting telescope? URGENT!!!?

I need to build a reflecting telescope for a project. Please explain ang give any ideas Also i need to know where i can find a mirror for it

Question by Chetan K   |  last reply

I have to create a planet habitable for the survival of human life? Answered

There is a science competition and we have to give details for a planet that has a possibility of sustaining human life. I am a bit confused as to what should I include. There is so much - Orbits and rotation, atmosphere, crust mantle and core, soil type, biodiversity, water, plants, food, metals, magnetism, gravitational force...

Question by ayusha1081   |  last reply

Help: I would like to build a switch activated by light from a star.

My good friends are getting married. they met 16 years ago. i would like to build a trigger that is activated by the light of a star 16 light years away. the trigger would turn on the lights set up for the party. I have a telescope and have found a good candidate star. what do i need to build it? is there a light sensor i can hook up to the telescope? how do i hook that up to a switch? Please any help would be greatly appreciated. thanks

Topic by ishmael101   |  last reply

How does one go about making a reflecting telescope, like Newton's?

What supplies do you need, as well?

Question by shanghai_breezes   |  last reply

What is the cause of gravity?

A friend of mine MUSAB said that  two bodies attract each other because the electrons and protons of both their atoms attract each other, however, I don't think this is the case, I have heard from some where else that it is due to distortion in space time created by a mass and geodesics are formed and they bend towards the center of the mass due to which every other body which comes in its gravitational field tends to move towards its center and all that stuff I have studied in detail. So who is right? If he is wrong, then please also specify where is he wrong, I think that individual atoms can not attract each other because of charge because an atom, as a whole, is a neutral particle. Thanks in advance.

Question by universal-physicist   |  last reply

Ethernet controlled robotic digital camera enhanced telescope? Answered

I keep wondering about how cool it would be if 100s of amateurs trained their robotic telescopes, hooked to the web, on one part of the sky, via commands over the internet from some astronomer who's got a hunch or just spotted a new spot on Venus or whatever. Those 100s of telescopes then took a photo at the exact same instant(or nearly so)and the same spot and then send that photo over the web to some big iron or a BOINC like app that would then crunch all the photos together to get a better picture of that object without having to go to Hawaii or Chile to get a decent shot... instant big lens astronomy?!

Question by pleabargain   |  last reply

Happy Birthday, Mr Laser, Happy Birthday ... to ... you

OK, so it's hard to do an impression of Marylin Monroe in a topic title.Today, is, according to google, the anniversary of the invention of the laser. First demonstrated in 1960, it was known as a solution looking for a problem - everybody agreed it was clever, but it took some time before it saw a practical use. Now, every single "western" home has at least a handful of lasers, ad they have seen duty everywhere from art to war, via medicine and astronomy.Time to have a quick review of how this tricksie piece of hardware (especially the LED variety) has been treated by our members: Laser-based projects.Laser vortex from this InstructableGoogle's laser results

Topic by Kiteman   |  last reply

Pager motors: Removing weight and driving wheels

Hello fellow life forms, I am currently working volunteerily at a local school, teaching young kids a bit about telescopes and astronomy. One topic I am currently planning is the mars rover(s) and I am planning on building a simple line follower as activity. As the budget is very low but I still want the kids to be able to build something to take home I am trying to keep it as simple as possible. After I ordered a pager/iphone motor a year back or so, I now ordered 100 vibration motors for $28.50 at aliexpress. They work fine but are smaller then the one I had before, a rubbery encasing makes them the same form factor.  (excuse the horrible pictures, I just have a older android phone) 1) The first problem is removing the weight. I have searched and found several tutorials (for example and aproaces, heat and regular pliers failed, for everything else I lack smaller tools.   I consider ordering those grip pliers here in germany, which one would be better?;=item233228bf95 or;=item3cdd210995 I also considered a watch wrist band tool as I have only a limited set of tools,;=item566039355f or;=item1e8539d1a5 or;=item485b0c8224 But I don't think I can adapt them to hold the motors. Any other tricks? 2) The second problem is to drive small wheels with those motors. With the vibration weight attached I can't drive a small foam or cardboard wheel, neither via friction nor a rubber band/belt. I hope it will work once the weight is off. I hope I can solve this issue, else I am stuck with 100 motors that are only suitable for bristle bots ;-) The vibration is strong enoug to move something, also attaching the motors to a cardboard square and directly touch the ground seems to have enough power. I could use a 3d printer to print a gear, but I would like to keep it as simple as possible. Also the groove bearing + shrink tube drive I have seen on another project would not be ideal to build with younger children. I initially was thinking of using bottle caps as wheels and wrap the motor axis with shrink tubing or isolation tape to drive the bottle cap by friction. Thanks for any ideas, advice or suggestions! -Marcus

Topic by schorhr   |  last reply