Green Baron

Yes, the moon is getting away due to conservation of momentum as @p1t1o explained. And the days are getting longer in the same turn. It won't leave earths orbit and as far as i know it will not force earth in a bound rotation during the "lifetime" of the solar system. Not sure, something around tens of billions of years if nothing comes in between :-)

I don't think there is a simple explanation. Afaik only the 2-body problem has an exact solution. A special case, the restricted 3-body-problem, (1 mass=0, movement in a plane) can be approximated. I am not a mathematician and can only accept what i read. For my understanding the general n-body problem quickly gets chaotic. Simulations can only approximate the general behaviour. Gravitation perturbations in solar system can be approximated, e.g. to predict a position of a planet at the time of arrival of a spacecraft. But orbits are in principle never really stable, algorithms are based on optimizations and simplifications and spacecrafts can correct the flight path. Hope that's generally not totally wrong :-) Edit: under 3-body considerations, bodies that enter resonant orbits are considered "stable".

Does local geology permit such a project at all ? I mean nature, not law. Watery sediments can easily be miffed if dug into. Also isn't this an area with immanent earthquakes and movements ? This really sounds at least a little hasty ...

Thank you, @kookoo_gr, so it is classic hdr technique, then. Will try this the next time, it's been cloudy in the past days. I have just registered me on Astrobin. And thanks for the wonderful M42 ! Give me some more time, i'll catch up ;-)

It seems like there are serious doubts about what was really measured. http://www.nature.com/news/physicists-doubt-bold-report-of-metallic-hydrogen-1.21379

Depending on the underground, tunnel boring machines would do this in a few months. They drill and leave a ready tunnel with concrete walls behind. Since decades. So this is going to be a private tunnel or what ?

My opinion in very simple words: news these days are mostly generated to server a purpose, as a medium for money making or to transport a political or religious message. This may sound somewhat paranoiac, but i am glad that the public is slowly getting aware, especially since the last year. If i would want to get more information on the actions of our governments (don't care which one), my question would be: how can you be sure that what you get from the news agencies is actually true ? How can you avoid falling for "news" generated to server a purpose (in my opinion 90%), governmental "alternative facts", political or religious influence ? In my opinion your task as a news page provider would be to secure a certain quality and transparency, what i would like to see is a really independent news source. But it might happen that such a source is quickly cut off from news supply or even declared illegal if it gets too uncomfortable ... see the leak-pages. Ah ... these are not the times for a revolution, i am 100 years too late :-)))))

Just a remark: arxiv is a pre-print server, the papers in there are not reviewed or published. I only did a swift fly-by of the paper. As far as i know atmospheric modeling of thermo- and exosphere is rudimentary anyway so if there is a discrepancy of a few mm/sec the models might need adjustment ...

You explain very well, sir ! Yeah, in the beginning i calculated, now i often just fly. From circular to circular orbit Hohmann is not too frightening. This link explains Hohmann step by step, better than Wikipedia, i find. So nobody has to recite it again ...

But that is easy. If i may not link to the wiki i must type it myself. dv is a measurement for the ability of a rocket to change its speed. It is nothing else than the amount of fuel thrown out at a certain speed. So the mass difference comes into play and a figure that says something about the speed at which the fuel is thrown out, the specific impulse. The constant doesn't matter for the explanation (propellant weight on earth is used for the ISP). Here you go: Natural logarithm of wetmass divided by drymass * specific impulse in seconds * earths gravity dV[m/s] = ln(startmass/drymass) * ISP * 9.81[m/s²] Example: Rocket mass before maneuver 100t, afterwards 50t. ISP of engine 300s. ln(100/50) * 300 * 9.81 = ln(2) * 2943 = ~0.69 *2943 = ~2030m/s. Edit: The formatting was done by the crappy forum software on save. Everything is meant as written, just ignore the strikes ...

I cannot resist my urge to state that the level in "Science & Spaceflight" sometimes amazes me ....

My fingernails are gone until then :-)

Ok, for 2 hours there was an open sky yesterday and i could do the third try with RGB, this time successfull. Conditions were suboptimal, it was windy and there were a few cirrus clouds. I couldn't get the image any sharper. RGB, no L because i don't yet know how to combine them properly without L dominating the colours, 8*2min each colour, no biasses, no darks, cooler inactive. Just stacked with DSS and colour channels combined with Fitswork. No further corrections. Will do a more sophisticated version and post it on Astrobin and hope to get a few tips from the savants ... My stuff is almost ready now (except for the tilt in axis), good weather may come :-)

Often fossil water is used to irrigate agricultural projects in the desert. It is not that far away, just 2-3km. Problem is that the level sinks and each year they have to drill a little deeper until the water comes out of reach, which could be the case pretty soon(tm) in Oman or Arabia. Arabs regularly use it for gardening and car washing ... humans just don't care about the future :-/ A quick search revealed these photos for those who need pictures :-) But they are 15 years old ... http://www.earthobservatory.nasa.gov/IOTD/view.php?id=2237

Geoscientist's questions: Why does a desert like the Sahara form ? Which arrangements leads to it ? Is it permanent or ephemeral ? How are global and continental circulation of winds and precipitation, evaporation balance of nearby waters, transport of moisture, can the soil hold water, (sub-)continental arrangements, transport of energy in nearby oceans ? All these factors are researched. A desert like the Sahara is not a constant thing like e.g. in the Permian what formed the Navajo Sandstone formation, 7.000 years ago neolithic societies lived there where today is a desert. Search Science and Nature and Elsevier journals if you want more info on that. If conditions are favourable for more precipitation in the Sahara then in a few hundred/thousand years you can plant Tomatoes there. Of course you can get yourself a hose (or dig a canal, same principle because must be maintained), but you cannot terraform on Terra. I have a problem with the wording here :-) Take a look at one of the Earth visualisation things (Google maps or so) and look what the Moroccoans have done, they are quite good at artificial irrigation. Or the Saudis or Omans in the Rhub-al-Khali. It is artificial irrigation by digging thousands of meters deep for ground water. cheers gb

Slightly smaller (10kw) are only backpack-engines for paragliders. Speaking of this, a backpack-engine for a tandem glider might be something to consider ? They are certified, lightweight and offer enough power. http://www.fresh-breeze.de/home.html or Techno-fly (no english website, but they claim to have a 25hp engine with a carbon propeller that all together weighs 17kg ...)

Thank you for the friendly comments :-) Grüße an die Elbe.

O, aeh, ... i greatly respect this but this is maybe not the right place here. Go to an airfield and join an aeronautical club where others share the same addiction. Do not rely on internet information ! I do not know whether there is an aeronautically reworked version of the pulsar engine, it seems to be a bike engine ? You cannot use a bike engine to propel an aircraft, sooner or later it will fail during flight because lubrication is not laid out for changing g-effects. My knowledge about this is totally outdatet, a long time ago i flew single engine pipers and robins but friends of mine owned and flew micro- and ultralights (max. 450kg TOW). I don't know what kind of contraption you are doing. Aerodynamically steered or through weight shift ? Do you build it from scratch or is it a kit (i assume so) ? Surely there are recommendations from the kit manufacturer. Weight and balance must be observed, stability of the frame, forces of gravity during flight for the fuel and lubricants circulation. Engines usually don't run long upside down. Also depending on the country you live in certifications and regulations do apply. Germany and France are liberal, Spain totally strict, the US in between. Usually engine and frame are selected all together because engine mount and connections are tightly integrated into the rest to stay below the TOW limit for certification. If it is a one of then talk to your countries aeronautical agency, they will gladly hand out all information you need and help get in contact. That is their job :-) Again, get in contact with other airmen/-women. The internet is not the place to gather info on that unless you know what you want. Says the friendly gb

The weather is improving. I'm showing off my next test. Can't continue with Plejades because they are right above in the evening and thus out of reach (camera would hit leg of mount). So i aimed at Orion. Just plain 10*4min, no darks or biases because test. Just stacked and no further ado. Seems like i am close to the focus now but having a slight tilt in the optical axis. Stars in the lower half are slightly prolonged compared to those above. Chinese brand washers, you know :-) Will probably have to go to fine mechanics workshop and have me a washer moulded. Slightly overexposed it seems ... Slowly i'm working myself towards showing something on astrobin or german astronomie.de and gather tips from the experienced. :-)

Yes, that IS an interesting question. I have followed the publications over the last years but i am not an astronomer. There is no easy answer to your question. Sol's Oort cloud has revealed itself through gravity and the origin of the comets, but it's total mass is very low compared to what's farther inside. Some objects might even be interstellar and only gravitationally bound on a temporary basis. If they are gravitationally bound their orbit times may reach 10.000s or even hundred thousands of years. This is according to the model of the formation of our system and that system seems to be somewhat special compared to what was discovered in the last 15 years. The accretion disk seems to be a common part in the formation of star systems because quite a few are being observed. But then things mostly seem to go separate ways (note that i am a little cautious with my formulations :-)). In our case things were sorted quite well, rocky planets inside (still, this observation is probably just about to change fundamentally), gas giants outside. What was discovered in other systems until now is mostly different. But the observations could be influenced by our limited observation techniques. Whether a cloud of icy rubbish forms depends on when and where the accretion disk forms and how the system evolves. Our system always remained in a quiet environment and could have been able to collect interstellar dust that is now more or less bound or even exchanged with neighbours. The cluster Sol originated from has dispersed but some of the former members are still detectable*. Before i blather too much: there is no easy answer to your question. Proxima Centauri may have an Oort cloud as well, until recently it wasn't even sure whether the star is bound to the Alpha Centauri system. If you want reliable information i'd suggest to search sciencemag.org and www.nature.com. Abstracts and references are interesting enough. Post here your findings ! :-) *Speculation: that's where we should look for life(tm) ... but they are so far away ... :-)

Good to see the SpaceX flying again ! They pointed out that the barge landing is "just" an experimental part of the mission, which first and foremost is to put the payload into orbit. Is it about the word "instantaneous" ? Maybe the instantaneous launch window was just was the name suggest, the possibility to launch into desired orbit at a certain time under certain conditions ... Just a guess.

I already asked myself what to do to meet the same field of view if one night is not enough time. I only will have to do it manually. 8 min are not that much of a problem here. The ccd cam (atik 383l monochrome) only offers fits or tiff as output formats and the docs say that fits (16bit integer) corresponds to raw data, so there is no choice for me. I found out that i must stay near when pointing at objects high above because the camera could hit a leg of the mount ... Also i prefer ksp or factorio when waiting :-)

lol ... cleverly arranged, isn't it :-))

A lot of things come to my mind that cost as much or a even multiple of what these experiments cost and that are completely useless, even damaging. But that would lead to politics. In my personal opinion far too little money is spent on science & education, all over the world.

I knew someone would do it :-) Yeah, i was very sloppy with that 2AU size interferometer, i don't check it, i just believe it. "You could see" means it would be resolved as the smallest possible disc with such a 2AU sized dish. But an interferometer does not collect more light than the dishes of its components (how could it), only the resolution is better. For such faint objects as dwarf planets they could probably not keep it standing still long enough (at least Nasa mentiones something like that). Earth based instruments like the upcoming E-ELT or TMT are better suitable for that. Maybe in combination with an extraterrestrial telescope. We'll see :-) JWST has 6.5m and a terrible focal ratio (they probably can switch between configuration, i don't know) and was mentioned above that it has a resolution of 0,1arcsec (though i'd assume a little better). So earths orbit in 1 parsec would at best resolved in 20 pixels, if everything else is at its optimum. No planet is big enough enough to fill a pixel, not even a proper sun (except giants).