Jacques

Why do we want larger scope ? To collect more light. This scanning telescope will not get more light. To get higher resolving power. The resolving power will not be bigger than the resolving power of the scanning mirror. Also you would need a mecanism with the same precission as a mirror the size of the whole telescope. New big size telescope are all segmented mirror. http://astro.nineplanets.org/bigeyes.html

I think a good way to go would be to use neutral color filter on the light source. You can have the specifications on the one you use to know how much light is going throught. A dimer on a ligth bulb is not very linear and the color change... An iris on the source can be good if you add an unpolished glass in front (to keep constant the geoometry of the light source), but you won't get a very big range. I also tought of white led that can be controlled electronicaly, but I am not sure how linear it can be. Hope that help

The light source can be a variable and it look like it is the case here, is it Norman ?

Maybe it is because I am french speaking , but it is not clear what that means. Could your friend scan these picture and send them ? It is realy hard to create a completely dark room, specially if you use very long exposure time. Did he tried to take a picture without any light source to verify that his room is completely dark ?

In what context does he take is photos ? With that long exposure it maybe astrophography ??? What does that mean ? In the context of astrophotography I can interpret that as the background sky is not realy black... This is caused by light polution (background noise)

You must define "clearer picture" ,"same bucketful of photons" and "at high or low level". The thing that is clear is that the shutter speed vary and the not the apperture. What can vary with shutter speed is blur caused by motion of the subject or of the camera and how luminous the picture is.

She was born december 31th and we are January the 1st . She is now 8 She will be 9 december 31th of that year and 10 december 31th of next year.

From what I remember no the output beam is not coaxial to rotation. The output beam is alligned with the magnetic pole of the pulsar and the magnetic pole doesn't coincide with the rotation axis, like here on earth the magnetic pole is not at the same place has the geographic pole.

My question is simple, but I can't find an answer with google or wiki:( How does Plank found that value ? [math]h=6.6*10^{-34} J s[/math] How did he derived it ? Thanks

I don't think that there is a lot of antimater in blackhole. No antimater have been detected in space. If some antimater goes to a blackhole good chance are that they enconter matter before passing the event horizon.

We can now see the tail! Strange comet indeed, it's the second time that comet burst like that. The first was in 1892, an outburst that led to the comet's discovery by British astronomer Edwin Holmes. The comet orbit is all between mars and jupiter so maybe a collision with an astroid may be responsible for that outburst, but the comet is out of the ecliptic plane... An other hypothesis would be that of tide effect from jupiter but it still very far from jupiter. May be we will need to send a space probe to solve the mystery

I imagined something similar, but for space habitat that can also be used here on earth. Melt a patch of basaltic rock, let say on the moon. Insert a high temperature resistant tube in it an blow in slowly hot air in it to create a bubble in the molten rock and let it cool down. All you need to do is to install some air thight door to get in that space. No material to bring except for the door and the life support system.

Last evening I observed it with my telescope ! It was a nice sight and I see that the form is more elleptical. Very bright and very big ( about 5 time the apparent diameter of jupiter). I will keep an eye on it. Look at how the size evolved in 1 day !!! Diameter comparaison

From http://spaceweather.com/ I thought that might interest some of you. I wonder what caused that brightening... Any idea ? May be the comet fragmented ...

The word "change" imply time. Maybe you mean distance instead of displacement... ?

Can I go one step further: You need motion to have space. Space and time are emergent quality of motion. I hear you say you cannot have motion without space. I tell you look at the expansion of space: you don't have space but you got motion. You have space only after some motion took place. I don't understand what you mean by displacement. Let me guesss: Motion is displacement over time.

There is a search on for the JPL Small-Body Database Browser, enter Ceres and you get: http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=ceres;orb=1;cov=0#orb You need to click on show orbit diagram. This applet use 2 body method to calculate the orbit. A simple google : http://dawn.jpl.nasa.gov/

Here is a link to an applet that might interest some of you: http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=apophis;orb=1;cov=0#orb

A photon with a wavelength the size of the universe Not sure but I think 0 is the minimum...

OK I will try to explain my question a little bit more. You observe the redshift of a galaxy and you can calculate that it was recessing at v. In the same galaxy you observe a cepheid and mesure the distance to be d. You do a bunch of galaxies and you build a curve of v over d , and you can deduce that v increse when d increase. But you can express d in term of time, if d is 1 billion light years we see the galaxy 1 billion year in the pass or you can tell time= -1 billions years. The closer you get to the present time the lower the recessing speed. Do you follow me ? If you take now to 0 time and the pass negative and future positive, it mean that now the recession is stopped. Is it a valid way to interpret the data?

Hubble flow tells us the more distant a galaxy the faster it goes away or an other way to tell is the expansion is a function of distance. It is based on observation of the redshift and on the distance mesurement of galaxy. I thaught about it an other way: The more you go in the past, the faster the galaxy goes a way or the expansion is an inverse function of time. How can we decide which interpretation is the good one ?

http://www.sciencedaily.com/releases/2007/09/070905203843.htm Theoriticaly possible for all wave length...

I think so, but I am far from being able to tell you that's it! Norman: I would like to be able to comment your work, but I lack the knowledge, but I am sure that some one here can understand you, and I would like to ear them. I like Elas post. Is it like the weak and strong force are dual of gravity and electromagnetism ? Like the plane at infinity is the dual of the point at center of the unit sphere ?

Swanson: At these energies, how can we make the difference between real photon scattering, and pair creation and the scattering of photons with electron or positron ? In the later case it make me think of the electron and the positron being the "force" carring particle for the photons interaction...

Does photons interacts? I mean something else than interference. For example if I have a photon coming from the right and an other comming from the left will they just pass through each other? Is the result of photon collision depend on the energy ? Like if I have two .6Mev photon will they produce an electron positron pair when they collide ? Stupid question but it bugging me