Supersharp image of planet Neptune taken from the ground

Originally published at:


I’ve read the explanation 4 times and still don’t get it but hey, cool picture!


Like you do.


I suspect you do get it, but I’ll bite anyway. The atmosphere disturbs light. By “undoing” its disturbance, a very clear photograph is possible. The lasers – straight, unmoving beams – excite sodium atoms which then project light back to earth. From the ground, the light from those laser-excited sodium atoms wiggles and thrusts and jiggles. Observing the apparent movement of something we know isn’t moving allows one to know, in real time, whether the atmosphere is jiggling or thrusting, hither or yon, on a millisecond-by-millisecond basis. (Maybe microseconds?) That information feeds into the shape of a special deformable lens, undoing the atmosphere’s best efforts to stymie us and making us all go “whoa, dude”.

(Now, this being BB, someone will entirely embarrass me with a far more terse, far more accessible, and far more technical explanation.)


Whooah indeed.

Sometimes, I love the whole world, and all of its awesome stuff.


… and beaming the images straight into the back of Mr. Big’s Limo! It’s almost too easy…


Yay! Obligatory “Science! It works, bitches!” around here…


I doff my metaphorical artist’s beret to the scientists and engineers who brought us that photograph. Well done, lads.


This is generally called adaptive optics, and it’s been around for a while. The LBT has been using this method for five years. The secondary mirror is 1 meter in diameter and 1.6mm thick, so it’s rather tricky to make. They had a period where they would make a mirror, them break it when putting it in its carrying box.

The mirror has about 600 magnets glued to its rear surface, and a whole bunch of DSP computers calculate the current to feed to each magnet’s driver coil a thousand times a second, based on the incoming wavefront detected from the guide star. The first time they turned it on and saw the image, they discovered that it worked right at its theoretical maximum acuity.

It’s just one of the many tricks they use on modern ground-based telescopes to make them competitive with space-based telescopes.


Laser Tomography?

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Sorry I’m late! :slight_smile:

Actually your description is pretty good, but here’s a little more detail:

This turbulence in the atmosphere is caused by small packets of air at slightly different temperatures than the surrounding atmosphere. These cells refract the light, making the image appear to come from a slightly different position; that is, the image of the object briefly moves to a different place on the camera at the telescope focus, smearing the image during a long exposure.

The adaptive optics method here is to use these artificial stars to measure this displacement, and deform the mirror to move the image back to the target position. IIRC, the average size of the cell is about 10 cm at typical telescope sites, so for a 30 meter telescope the image is passing through about a thousand of these cells across the entire mirror, so it pays to have several sample “stars”. (N.B. The cells are probably larger at this site, since the Atacama is high and dry).


All else aside, that is an amazing visible light picture of a planet

Here is the Huble version which is impressive enough.


I’ve read it 4 times and I stiill think it’s actual magic (as in the Arthur C Clarke definition).


Is this the cue for Bob Hope to introduce Charo?



Also, I think this qualifies as a unicorn chaser.

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Simply reverse the polarity.

Great news, wonder if the technique can be used for many of Hubble’s exoplanet tasks, i.e. direct imaging, transit imaging, radial velocity, gravitational lensing. If so it would boost the exoplanet hunt significantly!

Don’t think so, I heard the picture of Neptune was at the limit of their focusing ability, in as much as they had to stand on a chair.

Don’t get up, I will see my self out.

Neptune apparent magnitude: 7.-8.0; Alpha Centauri A: +0.01; Alpha Centauri B: +1.33, so both brighter; should be in theory possible for stars with magnitude < Neptune, no?