Green Baron

Nice. 8" is a reasonable diameter :-) Looking forward to your planet images ! Concerning the mount i can only give you the advice to do it right. Mayby one day (soon) you want to add a guidescope, a heavier camera, correctors/reducers/barlows, filters, adapters ... that's easily additional 7kg.

It was an ESO concept study of a 100m popeye but was decided that it wasn't manageable with current available technology. Also, at that time it began to be foreseeable that interferometry could take over the part of RLTs (ridiculously) and LLTs (ludicrously) in the future. But who knows, maybe with recent advances in adaptive optics someone will one day build such a pan for visual goggling. Now we're waiting for 30 and 40m telescopes as well as possible VLBIs with telescopes in space and terrestrial ones.

Oh, we are still faaaar from seeing planets around other stars. What we see is the flickering in the lightcurves as planets traverse in front of a star or the back and forth movement of the star (red-/blueshift) as it orbits together with a planet around the common center. :-)

Yes, sir. This is the harvest of current generation telescopes and active/adaptive optics. The next generation will be two magnitudes better resolutionwise. btw.: E-ELT construction: the mountain top is flat now (Cerro Armazones). Construction starts in may, they say ... TMT must hurry :-)

Am in discussion mode :-) Presuming aliens in the first place bears a danger of putting them as a cause for phenomina and thus actually leads to avoiding to research of the natural causes, as was the case with the silly megastructure around a dimming star. Natural explanation for the class of dimming stars later did not interest anybody in the public (search the Astrophysical Journal). I am sure that the same will be the case when we discover life somewhere. Did aliens bring it there ? Or take it to earth ? They must be somewhere ! But this thinking does not lead to findings about nature. So, i find it cool that they found an atmosphere and hope more will be found in the future. So, while all the aliens are content with their thinking "We are not alone !" we should try to prove them right :-) Edit: the article

Because science is not about guessing or believing. It's about finding out in a meaning that everyone can reproduce. So, yes, we must have proof. Not necessarily a tissue sample, there are more subtle ways. Life did not spread beyond earth in 100s of my. It took ~3.3bilion years for multicellular life to develop on earth. If you mean men on the moon than i must object, they did not multiply there, they just paid a few days visit and gladly and well trained returned.

The main problem i have with much of the work on exoplanets is that so much is based on assumptions and hypothetical preconditions that it is really close to guessing imo. Like "if there was water" and "if there was an atmosphere" and "if we interpreted this as flares" ... it seems like in the recent past people got ever more eager to outrival each other with these "ifs". I am not sure whether all these assumptions can be confirmed by observations in the future. I really would not be surprised if different explanations turn out to explain the flickering of some of these pixels that represent stars, or if some of our models that represent radiation transport in stars are not as applicable as we might think. We need bigger telescopes. Bigger is better, as is sooner :-)

Yes, speed of sound changes, but in the low percentage range for the altitudes we can move in. But as you said not the frequency. That will change with the medium, as you said in Helium for example. Maybe temperature and moisture can have a somatic effects on the human voice (cold :-)). Differences in pitch of a human voice aren't really noticeable with altitude. Even a radio call from Mt. Everest top doesn't sound (much) different in pitch, though it'll be hard and harsh from the cold. Sound producing cords in the throat don't swing faster in lower pressure.

The experiment is running. This could shed some light on why Sag A*: http://iopscience.iop.org/article/10.1086/312423/meta;jsessionid=F90E44C85FA310CCE522E46C2CC8137C.c2.iopscience.cld.iop.org This gives info on the setup: http://www.nature.com/news/how-to-hunt-for-a-black-hole-with-a-telescope-the-size-of-earth-1.21693 What they aim at and from where: http://www.mpifr-bonn.mpg.de/announcements/2017/2 http://www.almaobservatory.org/en/press-room/announcements-events/1151-attempting-the-impossible-taking-the-first-picture-of-a-black-hole Weather matters: they need a clear sky at all 8 locations ...

From paragliding and small aircraft i can tell that the sound does not change pitch in lower pressure. Though the paraglider's helmet itself, if full face, dampens the sound of the surroundings. Aircraft headsets and microphones usually filter out the noise of the surrounding. The better ones at least :-)

Here's the pre-print: https://arxiv.org/abs/1703.05815 The model is based on assumptions of liquid water and atmospheres, not observations, or am i getting something severely wrong ? Sorry for spoiling if so :-). Edit: the applied model calculations suggest that 1e is the only planet that could have kept its water at least partially liquid under the assumptions made. "Just right for life" sounds a little lurid ... All i remember is that no spectral traces of atmospheres were detected, or do we have new data ? Am heavily interested of course ...

The last one who tried to build a huge airship for transportation went bankrupt. The hangar is now used as a leisure park ... The airship never left the concept papers.

I found a huge pile of work on the radiation around black holes and accretion disks, for example in The Astrophysical Journal. But i think Science and Nature have texts as well on this. I only do not understand everything and right now lack the time ... :-/

Ask the flight handbook of each individual plane :-) It's mainly a matter of speed if we ignore safety consideration like tyres, ground effects, ... If the airplane can reach the speed necessary for take off at a given weight, wind and athmopsheric conditions than it can take off without flaps. Landings can be done with only little flap instead of full, at a higher speed and therefore more stability. This is done when it's gusty or windy for example. I am sure when you guys watch youtube videos of aircraft landing in adverse weather you will realize that many of them have the flaps only a little bit extended for landing. Yeah, wind IS important. It's the medium the aircraft moves in. A lot of flights are redirected because of wind (weather). Aircraft have limits for tailwinds and crosswind components. On the other hand, with a strong wind on the nose an aircraft lands almost on its own ... In the concept paper they consider aircraft types up to military bombers with a takeoff speed of 250knots.

I highly doubt that we can speak of habitability anywhere near an accretion disk around a black hole or neutron star. There is really hard radiation, thermal and x-ray all around that originate from the released potential energy as stuff falls into the black hole / hits the neutron star. I mean really hard :-) Protoplanetary discs around normal stars are a different thing, i'd say.

The telescopes on the EHT work in the millimeter or tenths of a millimeter wavelengths. Optical telescopes in nanometers (400-700 optical spectrum). Radio waves go up to 10s of centimeters, terrestrial radio meters, infrared is in between the optical and radio spectrum in the micrometer range. The other direction is UV nanometers, X-ray shorter ... ALMA and south pole telescope participate now, i read. So the site might not be up to date ? Next year a nice one will be ready, the NOEMA. They have a picture on their site showing the wavelengths of the observable spectra. It seems to be indeed the resolution that makes Sag A* a best candidate. Not sure whether stellar black holes, though closer, are just too small (10s of km) for observation (or better: for getting a close view), but they mentioned a black hole in M87, which is far away but a real one :-) Stellar black holes can have accretion discs if they have a close companion. Cygnus X-1 may have one and i am sure others as well as i think (not sure) X-rays are the main reason why they can be detected at all, and X-rays might be emitted by an accretion disc.

Yeah, sounds absurd. But this is about the second try to obtain an image of the vicinity of our galaxy's central black hole Sagittarius A* with the EHT (Event Horizon Telescope), a worldwide conglomerate of radio telescopes working as an interferometer. New telescopes where added and improve the chances of success this time. So, if you guys and gals find any interesting info on this, why not put it here ? I'd like to suggest to keep it "sciency", if nobody objects :-) Edit: gathering links: http://iopscience.iop.org/article/10.3847/0004-637X/817/2/173 https://arxiv.org/pdf/1607.03034v1.pdf

When exposed rapidly to lower oxygen partial pressure (>5000m for a sporty young person) funny things happen. The sense of judgement is severely limited. You feel great, invincible, but a simple calculation like glide ratio / altitude can become a real task.

Looking forward to the new explanations and models of how solar systems form. Until a few years ago we had the solar system with the rocky potatoes inside and the gas bubbles outside. The model was clear and comprehensible via the forming from a planetary disc, solar winds/radiation pressure, these things. With current generation telescopes since the 20xx, adaptive and active optics more and more special cases are discovered, rocks far outside from their suns, gas giants skimming the atmospheres of their sun, "rogue" (what a word) planets, "perturbers" (makes me think of a rebel, like in the Corsican flag), multi-star systems ... the first impression is that our system probably is not the typical blueprint of what happens around stars.

Long term adaptations to low air pressure work until about 5500; max. 8000 meters for a few specially trained persons at a very high risk and for a very sort time (hours). Anyway the risk of edemas rises. An untrained flatlander can have respiratory problems hiking at 2000m altitude. See high altitude sickness, long term adaptation to altitude of the human body. We're not made for that :-)

Expressing a severe doubt was not my intention (quoting myself 'cause too lazy ... :-)). I really didn't get the sarcasm/irony in @Razorforce7's post , that's all. From the papers that i read about it (and i definitely mean reviewed scientific papers) it might well be that it is a question of time and equipment since until the discovery. It just explains a lot of things too well to be done away with.

Oops ... :-)

Hu ? Nope, leave it open, planet 9 is postulated, not discovered as in a telescope. And until then it doesn't have an official name. Naming it would traditionally be the task of the discoverers and if they were consistent it would be from roman or greek mythology.

You mentioned the ariane maiden flight failure. But afterwards they did pretty well: a little advertisement. The insider-effect: you mainly see the failures because you work on correcting or avoiding them. See it that way: you'll form part of the future. I appreciate your work ;-)