Green Baron

Only found a train pic ... 2473 (Twothousandfourhundredandseventythree) can also be written as 1001101010012 or 0x9a9 or backwards 3742 It is an odd number, like all prime numbers ;-)

The unadapted human eye has around 10 good old exposure values of dynamic range. If i set it into relation to the exposure times of the bright full moon to it entering the umbra (10) then we are at the edge of what the eye can do without adaptation. The full moon on earth overshines most but the brightest stars. I can imagine that on the lunar surface without an atmosphere and everything being lit the contrast is much sharper and the surface reflection may overshine nearly all of the stars. One would probably have to enter the shadows and wait a while to actually see stars. Adaptation broadens the dynamic range to ~16ev (there may be individual differences). Adaptation of the eye from a normally lit scene to a starlit night takes around half an hour.

According to model calculations, in a binary system with a protoplanetary disk there are two stable configs for the disk: either in the sama plane as the binary stars, or rectangular to them. An example for a rectangular disk has been found: https://www.nature.com/articles/s41550-018-0667-x

Yep, if they are hydraulic, then they can potentially be controlled from anywhere where a cable leads.

Well, the rudder(s) of huge merchant or military ships can't be controlled manually. They are too heavy and profiled and love to move about when not in perfect equal flow. Forces in the range of many tons are needed to move and hold them in the flow. This can only be done with the help of hydraulics. For a balanced steering there can be two cylinders left and right of the shaft that push and pull equally against an eccentric (what is the correct technical term for a lever at a right angle on an axis ?) on top of the rudder shaft(s). On smaller boats (if not tiller steering) the helm turns a cog over which a chain runs, that ends in wire cables on both ends. These are turned around under deck and one end goes from the one side, the other from the other side around a quadrant that sits right on the rudder shaft. This mechanism can be configured without slack and holds even in dynamic conditions. It is old and works. Tall (sailing) ships have more than one steering wheel (helm) along an axis and more than one chain to move the quadrant(s). On occasions, more than one person (6, 8) are needed to hold a course. I can tell from experience that a 14m boat in dynamic conditions can not be steered against the sheets and flow even by a strong person. All of these methods need a mechanism to report the exact rudder position and for fine adjustment of the mechanics and they must not slack, not even slightly, or bad things can happen :-) Was that understandable ? Sorry if not ... tl, dr: Big ship: hydraulics, small manually controlled ships: quadrant. Or tiller. Or outboarder ...

A magma chamber exposed to seawater like 1883 ? That in today's densely populated world ? Hopefully not. People near Etna have the same preoccupation, Etna's eastern flank was reported to be moving, but it is not clear whether it settles or may one day give in to gravity, if the cause is pressing magma or crustal subsidence.

Certainly a dramatic change. A Japanese earth observation satellite has documented the change: https://www.eorc.jaxa.jp/ALOS-2/en/img_up/dis_pal2_eruption_anak_krakatau_20181226.htm http://www.gsi.go.jp/cais/topic181225-index-e.html

An alternative ! I love alternatives, the discussion is on :-) The Planet 9 protagonists on their blog site have replied: http://www.findplanetnine.com/2019/01/is-planet-nine-just-ring-of-icy-bodies.html tl, dr: they find the existence of a massive eccentric and inclined ring improbable but concede that it may exist. My 5 cents: The counterargument for the new hypothesis here is parsimony (archaeologist speaking :-)). Such a ring, stable over billions of years and with more mass than the hypothetical Planet 9, is imo more difficult to explain than a single body in the proposed orbit. Besides, the total mass of all things TNO (excluding Planet 9) is estimated to be magnitudes lower than what is necessary for the ring. But estimations can be corrected ... What do you guys think ?

2423

I get a pics of the hopper and when i click "next post" unrelated stuff, to say the least. Maybe OP wants to make sure that images in the album are limited to SpaceX stuff ? But idk ...

The stars come out ! Welcome the stars ! Hi all :-)

Many kinds of aerosols. It was mentioned that volcanoes, cloud cover, unspecific moisture, dust over desert/arid regions and continent wide effects over densely populated areas have their share in it. The state of the lower atmosphere (the troposphere to be exact) contributes more to the colouring and brightness than for example the stratosphere. Which is not surprising, the troposphere is the densest part and the place where weather occurs.

Acoustically and optically. And now i know what the cello reminds me of: Alistor Moody's broomstick ! Totally devious thought, i know.

It is actually even worse, earth's crustal density is ~2.7 (continental) to ~3.0 (oceanic), mantle density increasing to ~5.8 with depth. Then a juicy discontinuity at the core/mantle boundary to ~10, increasing to just below 13 in the inner core. Since the mantle makes by far for the most volume, it is safe to assume a medium density of 4 or even 4.5 for the calculation.

A DIY rocket that actually does fly :-)

I am not sure if satellites in GEO could not capture the effect, but i am neither sure they would. Anyway, a lot can be done from the surface of the earth. Lets add real world data from observation to the ideal model and we find that the moon's colour and brightness do not always obey and the contents of the atmosphere decisively influence scattering and other optical effects. Up to a degree that it has been proposed to use the moon's reflected light as an indicator.

Other way round, satellites, because they are closer, must travel through the zone of scattering and show the effect of changes of wavelengths much clearer than the moon. But i was asking for images from GEO as a satellite there spends a longer time traveling through the shadow phases. Anyway, the moon isn't always that read, this time Anak Krakatau migth have played a role in the hue (not my speculation) and the alignment of the earth's continents (African deserts, densely populated Asia, my speculation). Such a ring as in the picture is a nice rendering to visualize the principle, but not necessarily reality. Waiting for the first real picture from the moon :-)

Possible, why not. Colour and brightness depend on atmospheric composition and contents and can vary between a yellow/golden and reddish/brown. It has been proposed to try and use lunar eclipses as an indicator for the atmosphere's contents. Are there no images of a solar eclipse from geostationary orbit or other satellite than the ISS and weather satellites ? These show the lower atmosphere yellowish and the upper blue, just like a clear air sunset.

Glad i am not a vampire :-) From my place, the difference in exposure time for the moon from earth between the penumbral and the fully lit phase was 16 seconds to 1/60s (f/8, ISO100), that is 10ev difference (logarithmic scale, each ev is double the light of the former). The sky was clear due to a foehn effect. I assume the video is not colour corrected or processed in some way, @lajoswinkler ? It would be interesting to know if the sun rose above the ocean or a continent (dust, moisture), and how much of the bright white is eventually due to saturation of the sensor ... Btw.: they can do better: https://www.nasa.gov/content/sunrise-from-the-international-space-station https://www.nasa.gov/multimedia/imagegallery/image_feature_385.html

Well, ok, but this time no train pic: 2393

I find satellite images of the moon's shadow on the earth impressive.

Oh, I absolutely advocate manned space exploration (once it can be done and makes sense, for now probes can pave the way for later direct viewing, e. g. on Mars). And i personally think that, even if a few magnitudes of energy levels are still missing, the FCC should be built. Because we are talking about the Lorentz term, we will always be several magnitudes away, no matter (haha) what. JWST is at 8⁹ funds now, the ground telescopes that are being built are comparably peanuts (1-2⁹ funds), the FCC proposal sums up to 9-20⁹. This is absolutely in the range of big infrastructure projects, maybe higher. I only wanted to express that i can understand that people discuss the pros and cons, but of course i hope that one day there will be a go or a proposal for a better version without having to wait 20 years. Better sink the money there than ... elsewhere ;-)

Cool, is that the same cello that played Hans Zimmer's Pirates of the Caribbean theme ?

That is absolutely ok !

Welcome :-)