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Slashdot Asks: Cheap But Reasonable Telescopes for Kids?

cunniff Re: Dobsonian (187 comments)

As penance, here is a $65 mirror grinding kit, for a 4.25" mirror:

To make your own Dobsonian, just add a diagonal and stalk, a cardboard tube, plywood, a bit of Ebony Star formica, and some teflon pads and miscellaneous hardware.

about a month ago

Slashdot Asks: Cheap But Reasonable Telescopes for Kids?

cunniff Re: Dobsonian (187 comments)

Derp. Yes.

about a month ago

Slashdot Asks: Cheap But Reasonable Telescopes for Kids?

cunniff Re:Dobsonian (187 comments)

This advice is almost exactly the opposite of "good". You might be interested to learn that James Dobson, of Dobsonian fame, specifically designed the telescope to be simple to construct and use. The OP talked about the moon and Saturn. Both of those objects are very easy to see with the naked eye, and therefore very easy to point an alt-azimuth telescope at. An equatorial mount or motor drive is actually harder for a beginner to use than just a simple push-to-go-to alt-az mount. And any motorized drive you could get for anywhere near $100 is just junk.

All that said, you probably won't find a new Dobsonian scope for $100. There are some inexpensive alt-az refractors for about $120 - the Orion StarBlast 70mm for example. It has a finderscope, an erect-image diagonal, and a standard 1.25"-diameter focuser and two eyepieces. Might be worth a peek.

Alternatively, if you are interested in really learning a lot about telescopes, you could build one, starting with grinding your own mirror. You might get that done for about $100 for a 4.25" reflector.

about a month ago

Tesla Releases Electric Car Patents To the Public

cunniff Trust but verify (211 comments)

If I were personally going to use one of Tesla's patents in my business, I'd want a signed zero-cost GPL-like license agreement with Tesla. For example, Musk's good will is nice, but what if someone else were to acquire Tesla's IP?

about 3 months ago

Pluto Regains Its Title As Largest Object In Its Neighborhood

cunniff Re:And when Eris' atmosphere is measured... (138 comments)

From TFA:

Eris is just 2326 kilometers across—possibly smaller than Pluto, whose diameter is somewhere between 2300 and 2400 kilometers. The uncertainty arises because Pluto, unlike Eris, has air that complicates the interpretation of observational data.

about 6 months ago

World's Oldest Tumor Found In a Neanderthal Bone

cunniff Oldest *hominid* tumor, maybe (46 comments)

Paleontologists have found 150-million-year-old dino tumors, see

The university is welcoming four renowned curators from Carnegie Museum into its classrooms to teach seminars and use the museum collection, which is considered one of the world's premiere displays of natural history artifacts, for demonstrations. Included in the collection is a 150-million-year-old fossilized dinosaur bone complete with a tumor.

I would not be surprised if there are even older amphibian tumor fossils out there somewhere.

about a year ago

Can Older Software Developers Still Learn New Tricks?

cunniff Yes (365 comments)

Now get off my lawn

about a year ago

Bloomberg: Steve Jobs Behind NYC Crime Wave

cunniff The real issue (311 comments)

It's not the *cost* of the iPhone. It's the *black market resale value* that drives theft.

It's uncomfortable allowing a third party to be able to permanently brick your phone or other device, but if that were a commonly-used option, the resale value would quickly drop down close to zero.

As always - back up your data, and don't store important personal information on your easily-stolen device...

about a year and a half ago

Despite Clay Minerals, Early Mars Might Have Been Dry

cunniff Re:What about this? (105 comments)

Well, it could be sedimentary rock layers. But volcanos can also cause layering - consult the oracle about "welded tuff" (example image from Idaho)

about 2 years ago

Radioactive Decay Apparently Influenced By the Sun

cunniff Re:This is exciting (267 comments)

but, to some physics, perhaps a bit boring.

Err, make that, "but, to some *physicists", perhaps a bit boring."

about 2 years ago

Radioactive Decay Apparently Influenced By the Sun

cunniff This is exciting (267 comments)

Possibly the most exciting physics news of the year. Although the detection of the Higgs boson was big, it mostly confirmed what existing theory predicted. Interesting, important - but, to some physics, perhaps a bit boring.

If further measurements continue to verify this effect, there are some very interesting new physics to discover.

about 2 years ago

Is It Time For the US Government To Back Fusion At NIF Over ITER?

cunniff Re:well, i dunno (308 comments)

How many sticks of dynamite would it take at 15 times per second, to eventually push the stated goal of 200MW into the power grid?

1 stick of dynamite == 2.1MJ, if you can believe Wikipedia
15 sticks per second == 32MJ/S = 32MW
200MW/32MW = 6.3 sticks of dynamite exploded 15 times per second.

This assumes 100% efficiency to electricity, of course.

about 2 years ago

Graphene Membranes Superpermeable to Water

cunniff Re:Fresh water? (292 comments)

Spend a little time thinking about it, and you will realize that distilled water urban legend is silly. In your mouth, it is mixed with saliva and mucous and whatever else is stuck to your teeth, gums, and tongue. The instant it hits your stomach, it is mixed with stomach acids and whatever you ate recently. I.e. it is no longer pure distilled water. From there, the molecules wander through your body like any other water molecule. Distilling water does not give its component molecules magic properties.

more than 2 years ago

NASA Briefing on New Mars Finding This Afternoon

cunniff Re:My guess - (231 comments)

I noticed that too. My guess: they've found a currently active or very recently active volcano

more than 3 years ago

Japan Plans Moon Base Built By Robots For Robots

cunniff Re:Yay and nay (253 comments)

Close - I bet they get their funds by broadcasting the humanoids as they wear / hold / use various retail items. For a fee.

more than 4 years ago

Inventor Demonstrates Infinitely Variable Transmission

cunniff Newton's Third Law? (609 comments)

For every action, there is an equal an opposite reaction. So, when your monster torque motor is spinning the input shaft, surely it is pushing against the counterspinning shafts with exactly that amount of power? In other words - won't the mechanism (electric motor, flywheel, etc.) that keeps the counterspinning shafts running at the desired speed ratios have to overcome this reaction? It's possible that the frictional and mass inertia of the system helps some, but how much?

I'm not an ME, but the explanation of what the required control motor power is relative to input motor power is very thin here. Be very interesting to see what the detailed input / output / control torque & power measurements end up being.

more than 4 years ago



One in five stars has an Earth-sized planet in its habitable zone

cunniff cunniff writes  |  about 10 months ago

cunniff (264218) writes "Remarkable statistics from the Keck Observatory on Mauna Kea, Hawaii — 22% (+/- 8%) of stars have an Earth-sized planet in its habitable zone. From the press release, UC Berkley graduate student Erik Petigura says, "What this means is, when you look up at the thousands of stars in the night sky, the nearest sun-like star with an Earth-size planet in its habitable zone is probably only 12 light years away and can be seen with the naked eye. That is amazing,"

This, of course, raises the Fermi paradox again — if alien life is common, why haven't we seen it yet? This study will be used to spark further investigation, including proposals for space telescopes which might be able to image nearby Earth-sized planets."

Link to Original Source

First "Goldilocks" exoplanet discovered?

cunniff cunniff writes  |  more than 3 years ago

cunniff (264218) writes "According to a press release sent out today, the Keck Observatory on top of Mauna Kea, in Hawaii, has discovered the first "Goldilocks" exoplanet — a rocky Earth-class planet within the liquid water zone of its parent star:

The new planet, known as Gliese 581g, is at a distance that places it squarely in the middle of the star’s “habitable zone” where liquid water could exist on the planet’s surface... Gliese 581g has a mass 3 to 4 times that of the Earth and an orbital period of just under 37 days. Its mass indicates that it is probably a rocky planet with a definite surface and that it has enough gravity to hold on to an atmosphere, according to Vogt.

The parent star, Gliese 581, is a red dwarf in the direction of the constellation Libra."
Link to Original Source


Secret Math of Fly Eyes

cunniff cunniff writes  |  more than 4 years ago

cunniff (264218) writes "Wired Magazine points us to recent research which demonstrates an algorithm derived from the actual biological implementation of fly vision. According to the paper:

Here we present a model with multiple levels of non-linear dynamic adaptive components based directly on the known or suspected responses of neurons within the visual motion pathway of the fly brain. By testing the model under realistic high-dynamic range conditions we show that the addition of these elements makes the motion detection model robust across a large variety of images, velocities and accelerations.

It is claimed in the paper that "The implementation of this new algorithm could provide a very useful and robust velocity estimator for artificial navigation systems." Additionally, the paper describes the algorithm as extremely simple, capable of being implemented on very small and power-efficient processors. Best of all, the entire paper is public and hosted via a service that allows authenticated users to give feedback."
Link to Original Source


Lunar Reconnaissance Orbiter images Apollo sites

cunniff cunniff writes  |  more than 5 years ago

cunniff writes "As has been discussed several times, the Lunar Reconnaissance Orbiter has a camera with sufficient resolution to image the Apollo lunar landing sites. Today, they posted the first results. Images of all the landing sites are there, with Apollo 14 being the current highest resolution — the astronaut tracks between the lander and the ALSEP package are even visible! From the article: "In the current collection of images the best feature discrimination is in the Apollo 14 scene (astronaut tracks and ALSEP) even though the highest resolution picture covers the Apollo 16 site. This counter-intuitive result clearly shows that increased illumination (high signal) is a very significant factor in the true resolution of a picture." It is anticipated that even higher resolution photos will follow in the coming weeks."

Successful Launch of 1:10 Scale Saturn V

cunniff cunniff writes  |  more than 5 years ago

cunniff writes "Several "geek" sites over the past few weeks have had stories about Steve Eves' quest to launch the largest scale model rocket ever. Today, it launched successfully in Maryland. The site with the original story has video of the launch and successful recovery."
Link to Original Source


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