Liquid Metal: Mercury (Hg) in Slow Motion has been added as a related post - related requested by oritteropo on that post.

Some of the best ideas are too obvious to conceive.

Liquid mirror telescope- what a great simple idea.

Tags for this video have been changed from 'liquid mirror telescope, spinning mercury' to 'liquid mirror, telescope, spinning, mercury, astronomy' - edited by kulpims

*quality

Boosting this quality contribution up in the Hot Listing - declared quality by kulpims.

Did the mirror EVER look smooth in the video??

No, and am I the only one surprised that someone is spinning it by hand? I would have thought to get any kind of useably flat surface you'd need a lot of control over the spin. If what we saw in the video is acceptable I'm pretty sure I could grind that out of glass in an afternoon with a dremmel...

We have to assume they have a motor and the mirror actually looks smooth at times. The video feed of objects passing overhead was very sharp.

Only when they were using it, not when they were spinning it by hand to show the waves in the mercury.

I'd have liked a shot of it with the motor running too.

http://en.wikipedia.org/wiki/Liquid_mirror_telescopes

Check that crap out, ferrofluid mirror potential! What I wonder is are the optical properties of liquid metal any good. For instance, they are using gold in the James Webb telescope because it reflects nearly all infrared light. What would the optical quality of these metals be? Sometime tells me polished glass structures would be both higher resolution and use materials that are optimized to reflect the spectrum you are interested in. The Wiki seems to indicate the real advantage isn't in the optical quality, but the relative inexpensive in creation. Much like paying a hooker for 5 years of polishing your nob, polishing a mirror is costly.

"Hey John, what do you do again?"

"I spin a giant pool of mercury for eight hours a day. If I sneeze on you, you'll get mercury poisoning."

It is probably a near perfect mirror from this liquid mecury.

The big problems with liquids for telescope surfaces are -

1) gravity - the mirrors can only point straight up

2) the thermal coefficient of expansion for liquids is huge, as temps change, liquid components are dimensionally unstable

I suspect what you see is the state of the art for liquid mirrors and you shouldn't expect to see much more in our lifetimes.

Mmmmmm.....years of meticulous grinding!!

I don't know why they don't just spin molten tin and pour glass to float over it. Then pour molten tin on top while still spinning to cover the top curve. That's sort of how they make flat glass at window factories. Then silver it with vapor deposition.

Comment hidden because you are ignoring dag.(show it anyway)

Pretty cool. I've been to Cloudcroft several times because it's near my Mom's house in Las Cruces, didn't know this was there.

I was thinking the same. They never showed it running at full speed! I saw another newer documentary bout this same telescope and you couldn't tell it was liquid under normal operating conditions. it looked like a curved piece of mylar.