Green Baron

I have no idea about missiles and military guidance. Classical astronimcal navigation is probably not fast and accurate anough. A good navigator on a sailing boat can take a position within 3 nautical miles of what the gps says. Before the times of electronics even planes on intercontinental flights had to navigate with the stars (including the sun). Until the 1960s i think ... Evil voices says that most of the kids on the ocean today can only sail there because of the electronics :-)

It's incredible for someone who hasn't seen that before how many climate- and vegetation-zones there are on a volcanic island. Concerning temp., there might be snow up there at 2400m (well, a few cm and it won't last long) and people are swimming in the atlantic in 22°C (air and water). The caldera rim is in the line of sight from the beach. Also, great foto, @James Kerman, messed up my whitebalance for hours ... :-)

I am not surprised.

Ok, relativistic speeds are not necessary to reach the gas giants. Time in exchange suffices. Edit: That was unsciencey. If i got it right, concerning special relativity, any speed difference, and be it 1mph/kph, is relativistic concerning relative mass and time. The gentleman in your example is right. But pls. elaborate on your opinion because i am eager to learn. How can people be kept alive and healthy over years in a spaceship ? Where is the technology to do so ? Pls. show me that green house food is sufficient or that a large enough storage of dietary stuff can be carried along. And pls. try to keep it sciencey, no social media data. How can a crew be shielded from radiation in space ? The latest i heard on the subject from medicine was that the problem is underestimated. NASA stated somewhere that the crew could hide between the stored stuff during flight. Musk said that a (yet unexistent) spaceship could turn the engines in the direction of the radiation. Does that sound like awareness and a sophisticated method ? Your statement about radiation risk ignores data from Hiroshima, Nagasaki, Chernobyl and Fukushima. I kindly ask to research on the matter. I offer a third solution: Maybe some of the "pessimists" are at least partly right ? Might that be ? At least to me it happens from time to time that the other side is right ... Cheers :-) gb

The future isn't depicted, it hasn't taken place yet ... ?

Motorhaube. But here i'd have to say el capó ... Why ?

On the danger if straying off topic, my best knowledge about orthography was probably short before i began using programs and spellcheckers for writing. I have one pc (the one i'm at now) that has no spell checking installed (and i am too lazy to sudo aptitude install ...). It irritates me when i do not see any red underlining ... it can't all be correct :-) Are we allowed to take a spellchecker to Mars ? Information has mass ...

Tststs ... only military applications come to your minds ? :-) Did GLONASS ever reach a reliable state ? Also, i know us europeans, i will be patient before i switch any navigation gear from GPS to GALILEO :-)

Temperature between 10(°C) in the morning and 17 in the afternoon. That's a little less than last year at the time, overall a little less than the median temps. Noone gets me back to snow and ice. Never ! Jamais ! Niemals ! Jamas !

Yes, sulfur (btw.: f or ph ?) is no rare element. Time to move :-)

Hmm, where did they get the marsian soil from to make concrete out of it ? "Lunarcrete" is hypothetical. "Cement" needs to be produced and water imported. Or a magic spell involving sulfur. Our future in the stars is first and foremost dependent on finding means of transport and ways to stay healthy in a deadly environment. I don't see that in the next decades ... edit: but if we get that far, then yeah, we'll become hobbits in space, the kings under the mountain in their halls of concrete. Maybe scented concrete ? :-) yae (yet another edit): Since the link in the above link seems broken, here's the new link to linked paper on the preprint server: https://arxiv.org/abs/1512.05461

Besides dust particles in the atmosphere from an impact small enough so that the atmosphere is still intact, water vapor aka clouds reflect the sunlight. They either reflect it back to the surface, trapping the energy in the lower atmosphere or back into space, depending on thickness and cover. An earth wide cloud cover would on a short term actually lead to abrupt cooling (increase earths albedo), less energy reaches the surface but is reflected on the upper side of the cloud cover back into space. The resulting cooling of the surface can lead to snow cover on land when the water vapor condensates (snows), thus increasing the albedo even more. If enough of the surface is covered by snow the energy of the sun will not suffice to melt it, the snow covered surface will reflect too much energy back into space. The then clear atmosphere will amplify this effect. It would need a dark dustcover on the snow to free the earth from that state. More info: "nuclear winter" as a preliminary phase of this scenario or "snowball earth" hypothesis as a stable climatic state. :-)

Relative velocities for solar system bodies crossing earths orbit are between 8 and max. 70km/s. The average is around 17km/s. This takes into account for earths speed around the sun of 30km/s. I got that from NASAs NEO and impact risc pages. It seems logical to me, the lower limit could be an object on a similar orbit and the upper limit one from the Oort cloud. I am not sure about the videos scientific significance. It might well be that the result of a collision mars sized and above creates a new asteroid belt with a few major objects. Earth "survived" the Theia collision just barely ....

Thank you :-) The forum can be fun. These were only reminiscenses, my license expired looong ago. As you mention TCAS: this a very sad example of how it works.

Just an annotation @Jonfliesgoats: constant bearing is as you say the principle to eyeball a "close encounter", it has it's roots in maritime navigation and boat "captains" (savvy :-)) of recreational vessels as well as the professionals do this muliple times a day. In 2D and with the speeds of boats and in dense traffic it's very easy to watch another traffic over a few minutes and tell whether it crosses your bow or your stern, depending on how bearing changes. It is an approved method and besides others used to judge which rule of collision avoidance applies (see "colreg"). Having flown propeller planes myself years ago i can however say that in 3D and with the speeds of aircrafts, even small ones, reaction times are very tight and the silhouettes of the "opponent" very small. I can't remember that it was officially tought and wouldn't rely on the method when underway in VFR, because the application of constant bearing needs time to judge whether the bearing is ... well ... constant. Fly safe :-) Edit: just for clarification: constant bearing & decreasing range in combination are the interesting part. A vessel with constant bearing but increasing range is uninteresting.

Yes. It is. Totally. It has the same totalitarian habit than many other religions, works against science where it can, tries to kick out science from public education and discredit scientists and put it's own nonsense in it's place. It is pure and total anti-science !

There's a simulation somewhere of the Theia/Earth collision, the event that formed the moon. The bodies are literally reconfigured. Climate ? Nope ... :-) Collisions with objects of several 100km diameter ("Ceres sized") belong to the times when earth was forming. Today such an event would probably delete bio-, cryo-, hydro- and atmosphere. I don't think anyone (except discovery channel :-)) really calculated through it, based on current knowledge, but just have in mind that the skin on geology is terribly thin. Part of the atmosphere could be lost into space. That'll be a bad day for life :-) Maybe some bacteria could have a chance to celebrate a second birthday ...

1.766E+9 is (a variation of) the scientific notation, meaning 1.766*(10^9) or 1.766*1000000000. Hope that helps. Edit: ... but 1.766E+9(2/300,000- 2/300,000) smells like 0 or 1 depending on where the bracketed eypression belongs to, or am i mistaken ? Orbital speed formula: v = sqrt( G*M * ( 2/r - 1/a ) ) where a = semimajor orbit axis, r is altitude of orbiting body above center of M, which is for the ease of it the mass of the planet/moon (but see why !) and G is approx. 6.674×10−11 N⋅m2/kg2 (pasted from elsewhere).

Me again. Though i am fascinated by everything spacey i allow myself the hint that this is based on a pre-print server paper (arxiv) and not (yet) suitable for a citation. I mean in a strictly scientific sense. Flying over the paper on a hyperbolic trajectory i read the planet is assumed to have 1.6 earth masses and a calculated average surface temperature of 600K. If it is really water or methane vapor it must be under a very high pressure. I do not understand how the authors come to the speculation of "a substantially H2O-rich water world" as one possible end of a "range of interior compositions". But, well, i'm just a computer gamer :-) (edit: and a little sceptical)

Hehe, oooops :-) ... maybe google is not the best search instance ? I know binning from photography, espacially astrophotography. There it describes a process that combines adjacent pixels into a superpixel. Like 2*2 or 3*3 arrays, it reduces resolution but enhances sensitivity and signal/noise ratio. I hate to link to Wikipedia, but this article might help you find out about how binning and die find together. I must admit i haven't thoroughly read it because i know little about these things. :-)

@The Raging Sandwich: in a simple way, that's hilarious. But on second thought i'm not sure if it really is. I better stick to the simple way ... :-)

The dirt is just superficial. Can be blown off without much effort (GRB, impact, ...). GRB comes statistically and out of the blue. Impact is improbable and needs to be really big. It was pretty improbable that it got that far in the last 4by. Given the way we treat our environment and ressources it gets ever more probable that one day soon(tm) there will not be enough room for everybody. So far so clear. But evacuate ? Whom ? Where ? With what ? How to make a living elsewhere ? And who guarantees that things go better there ? It'll be a very vulnerable and unstable artificial environment. Of course everything is possible in a science fiction movie and in "Science & Spaceflight" :-))) The biggest dangers are our own changes to the environment. The realistic approach is to be more careful with what we got. I have my doubts that we're intelligent enough, history (not pre-history !) teaches us that humans only care about the future on a personal and short-term basis, the own offspring is not included. We are selfish (i mean hat personal, not as a species) and that alone is a counterargument that such an effort will ever work. Not speaking of the technological impossibilties of an evacuation.

Na. The screenplay script stated: evil gangster catches poor Russian kosmonauts and we need a doublezero agent to save the world. ... if i recall the right movie :-)

The longest lightnings, distance and time: http://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-16-0061.1?af=R& :-)

The 8th astrophotography contest of La Palma closed on 15th of november, these are the winners: http://elapuron.com/noticias/sociedad/97799/austriaco-gerald-rhemann-logra-primer-premio-del-octavo-concurso-internacional-astrofotografia/ If you're interested in timelapses, watch this guy. Scroll down a bit for the real nice clips, and lean back ... http://www.elcielodecanarias.com/timelapses/ A showcase for the latest works of amateur astrophotography http://www.astrobin.com/ is a nice link. Most people include telescopes, mounts, guiding, cameras, filters, exposure times, software in the description. English speaking community discusses on http://www.cloudynights.com/page/index.html and forums.