Green Baron

Guys don't you think that, if someone wanted one day to fly a rigid wing contraption on Mars, it would have a different design than a standard aircraft on earth ?

Andromeda ca. 3.5*1,5°, m42 ca. 1.5*1.5°, together with the upper and lower stars of the sword maybe the same size as Andromeda galaxy ... +/- window cross. This might be a good opportunity to calculate your field of view from chip size and focal length ;-) And you need a tracking mount for that thing !

You can see it with the naked eye, the blob under Orion's girdle. Most scopes will need a reducer to get the whole thing. It was my first try 1 year ago. So, that's mow an excuse to get back at it. Next week ... :-)

Hey, the ExoMars TGO is fine, we had our fun with Schiaparelli and that what apparently happened to the Breeze stage after separation doesn't count. Entertainment and thrill included

You're mean :-)

That is my information as well, @Hannu2. The composition of earth's core is mostly inferred from iron meteorites which are composed of Iron, Nickel and ppm of other elements. Edit: Ok, so i went on a search since the density discussion may come up again. I knew experiments were carried out with diamond anvil cells but i didn't remember when and where. It is not ready knowledge as it is all a little impractical :-) Here you go, iron experimentally compressed to 72GPa, density 9.64g/cm³, indeed needs to be mixed with lighter elements (like S/Si) at the earth's core in order to meet the geological constraints. So, no problem with the high densities of planets. In contrary, even the high densities allow for a whole lot of "rocky" material. If you ask why then look at the assumed pressure of the earth's inner core ;-)

Anecdote, totally unrelated: Whales sleep at the surface. Sure, they must breathe. Which is not a problem for a merchant ship. The cadavers of the poor animals make for a few days of naval warnings until it sinks. But a sleeping whale is a danger for small sailing boats on the open waters. Several incidents are known, with consequences for both, even with the loss of the boat. What do you do when you're single handed and can't stay on watch 24/7 ? You count the odds and hope for the best ... Which is of course not an option for space travel :-) Same for drifting containers.

Not a single. Our telescopes are becoming better. These things are (probably) just not that rare.

Nope. The initial crack is the shock wave, explosively expanding air from the lightning channel that reaches you in a direct line (Edit: the shock wave, not the channel of course ;-)). Maybe multiple shock waves at different sound levels if the channel branches. It can branch out of sight inside the cloud as well. The rolling otoh are echoes and reflections from ground, objects, clouds or even distant parts from the lightning's channel. It is not dependent on the frequency but the time it takes for the sound to travel from source to ear. No. See above. Speed of sound only very slightly depends on frequency (air is regarded non-dispersive) and it surely does not travel in a curve. The farther away travels longer distance and mixes with reflections from closer sounds. Sound wavelengths in air travel all at the same speed. Btw. the thunder frequencies aren't that wide spread, from low infrasound to a few hundred hertz. No standard pitch :-)

Normally i keep my opinion about such contemporaries to myself .... ... but in this case i honestly hope he makes it. And makes it further into space, so that he can acquire his proof of a round earth and settle the matter. But i fear that the science and nature he is scoffing at will be the one who kills him. Mechanical energy conversion, cold deformation, oxygen partial pressure ... and such maybe even fuel the conspirators (conspirers ?).

Is this authentic ? If so, then well, i'd have to admit that Nasa has not the dreamer's monopoly ... :-)

Stealing a car is much easier than stealing a spaceship. ...

F

Well, or a false positive, as suggested by the link in the OP. The planet/binary partner is unconfirmed, is that correct ? A scientist must always be ready to revise his/her views :-) Edit: sorry, not the OP, the arxiv-text linked a few posts under the OP. Also, a python-program called batman ("bad-ass transit model calculation") mentioned in the text doesn't really sound that serious ... ?

*sigh* No, it is an asteroid from a system with a lot of dust. And it is long and red and soon out of sight. http://www.eso.org/public/news/eso1737/ and https://www.nature.com/articles/nature25020 And our telescopes have recently become so sharp eyed that they can detect these rocks. More will follow in the future. I'd be so happy if we could separate the fantasy stuff from the science. It is not a spaceship, nor a fort, nor an apocalyptic rider or anything else sprung out of cheap fiction stories.

On the danger of repeating myself :-): "Never judge an outcrop from afar !" Edit: but that's what it looks more like to me. I only didn't want to spit in their soup. Haha, i'm kidding, of course. Or am i ?

Sure at one time in the future on the moon or mars somebody will dang in a loose screw with a stone right at hand and contemplate about the definition of "stone age".

On the surface ? If you're content with ole Newton then g= m/r² where m is the mass of the body and r is the radius. Result in multiples of earth's g.

It must be Santa's sledge ... Edit: "launch keeps on slippin' slippin', into the future ..." hummdidumm ...

Well, as the supposed high density seems to be of such concern, that is really not a problem. We all know that there is no excuse for density to not become infinite if under the persuasive influence of enough gravitation :-) (was that grammatically correct ?) Density of earth's assumed iron center is estimated to around 13.0 to 13.6 g/cm³.

Moon first, then Mars sounds reasonable.

Yeah, don't give too much for it. It is only a very coarse estimate from the size (in case of the transit method the duration of the drop) and the orbital period which leads to the mass (example: http://news.mit.edu/2013/new-technique-measures-mass-of-exoplanets-1219). With radial velocity (large planets only i think) determining mass is a little easier if we assume that our understanding of a sun's mass is correct. Sun's are naturally somewhat better understood as planets :-) And always keep in mind that with very few exceptions all measures are indirect and may change as our methodology evolves and instruments get better. More links with easy explanations: http://lasp.colorado.edu/education/outerplanets/exoplanets.php https://www.nasa.gov/ames/kepler/measuring-the-mass-of-a-mars-size-exoplanet But maybe somebody else can shed more em emissions on it ? I am hasty ... And always do read the papers that announce a discovery, methods are described if they are serious ;-)

Yeah, i have read that as well. If needs degenerated matter for the densities at earths inner core then so be it. Read the paper that @ProtoJeb21 linked in the Trappist thread : https://arxiv.org/pdf/1711.05691.pdf Besides (dull slogan:) moar data ! we also need more methodology work because there are a lot of variable properties of the stars, that we just assume to have certain values and deduct then the properties of our assumed planets from them. A slight change, for example in the density of sun spots on the respective sun's surface, changes planet properties likewise for those who have been deducted with the transit photometry method.

Yeah, it might be too early for an electric long range truck for full commercial use. It'll probably need more legal "stimuli" fpr them to be used widely, if at all in the near future. One of the huts has a sleeper under roof and a coffee machine for those who spend several days in them. The other is just planned for shorter trips without that. Technically they are probably the same.

That's because Mercury has a higher metal part than a planet its size "normally" (according to the standard model for the forming of our solar system) would have. The working hypothesis is that it has been stripped from a part of its mantle by collisions back in the day. It becomes clearer (i think) that there is no general rule to the densities of planets and the model for our solar system isn't easily transportable to other systems. It might well be that some planets are just naked iron cores (density 10 or even more g/cm³) while other might have a high part of volatiles, like, let's say a KBO in our system, density ~3g/cm³ and less.