香港天文論壇

if the rocket is moving very quickly on the sky (and the telephoto lens is tracking it), the moving object is probably a stationary object for us, i.e. a star. It appears so much bigger because it is out of focus.

just my thought..

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skynam 寫:

Wah!! 寫:若你明白我所說的，就會知道你的設計不可能浮起……

...便會從水平方向的反作用力F2改變為垂直方向的反作用力F1...

No, the force will not change direction in this way.

Also, you cannot fix the force of the spring system (to be 9000N) because it is dynamically determined by how much force you pull on each side.

(sorry for digging old post)

I borrowed the picture as an introduction slide in my talk (with image credit of coz'). I have to say the people (astronomers) are truly amazing by this image taken with such a small telescope.

take it easy, I think it's natural for someone who has heard about HDR to have idea to construct such picture.. [茶]

罗伯特·胡克 = Robert Hooke?

so much doubt about the info in the news...

skynam 寫:會考慮尋求徵求有沒有香港的大學可以合作應用上的研發

Sorry to say that, if the idea can't pass the fellow science teachers and amateurs on this forum, I don't think it will get any interest from the people in the universities..

http://abcnews.go.com/blogs/technology/ ... y-tribute/

299792458米 = 1 光秒 [茶] http://www.facebook.com/photo.php?v=108151032579618 睇唔到 你一定係用PC（・・？ 其實係舊年天文學獎，冇乜特別，只係咁啱見到個光速值。 我放喺Utube，你睇下播唔播到 … http://www.youtube.com/watch?v=HiFEflh01Qc [off topic] that's becoz' of the permission.. anyway, do you have the one for 2009 shaw prize ? ------------------------...

Zubenelgenubi 寫:

quantumkit 寫:299792458米 = 1 光秒
[茶]

http://www.facebook.com/photo.php?v=108151032579618

睇唔到

299792458米 = 1 光秒
[茶]

it IS canon 60D with modified cooling...

http://www.centralds.net/en/astro60d.htm

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There was a movie about this:
http://www.youtube.com/watch?v=BXRjmyJF ... CCAE1DC3AB

look at how small Venus passed across the Sun surface during the transit. Such object near the sun would be even bigger in order to match the angular size.. Not saying this is impossible to have alien UFO though..I hope our skeptical analysis isn't too discouraging for you =) take more pics of our S...

even if the lens was not moving, the sun would still move inside the frame due to Earth's rotation, right?