cantab

1. If the view of the Sun is actually blocked, well that's an eclipse, and here's one of Saturn taken by a space probe. Depending on the orbits this could happen every time the moon goes round its planet, or it could be rarer. If the view of the Sun is not blocked, well that's a crescent planet. Considering that the Moon is easily visible by day from Earth when it's up, unless the crescent is extremely thin, a gas giant of similar or larger apparent size would be no problem. 2. They won't stay 180 degrees apart, but will drift. Now it is possible for the arrangement to be stable in the long term, as seen with Janus and Epimetheus orbiting Saturn. At any given time one is in a slightly lower and thus slightly faster orbit and slowly catches up, but when they get close their gravity interacts to effectively swap orbits, the one that was faster is now slower and drifts away, before eventually being caught the other side and the process repeats. As for what it would look like, from one of the moons its co-orbital partner would keep a nearly constant apparent separation from the planet. In the case of Janus and Epimetheus their orbital periods are each about 0.6 days and it takes 4 years (Earth) for them to complete a cycle. 3. It's straightforward, and indeed quite natural, for eclipses to only occur twice for every year (roughly) of the parent planet. That's how it is for Earth and Moon. It's harder to make those eclipses last half a month though. 4. There would almost surely be light scattered through the atmosphere of the planet. For Earth and Moon, the Moon is clearly visible when it's eclipsed and furthermore appears brighter than when it is lit by Earthshine. It's likely to be the same for your planet and moon - "Eclipse days" will be dark compared to normal days, but possibly brighter than a gas-giant-lit night and much brighter than a gas-giantless night. That said, a lot depends on the atmosphere of the gas giant, perhaps a certain composition and structure would make eclipse days very dark. 5. Depends greatly on the apparent size of the gas giant. With the moon's orbital period fixed, that in turn will depend mainly on the gas giant's mass which will set its own size and the moon's orbital radius. It also depends on the gas giants albedo which could be anything from about .1 to .8 assuming the moon has Earthlike climate. Note that even the low .1 value is higher than Earth's Moon, so a gas giant at night is likely to appear pretty bright.

Worried about your food in a power cut? Simply solder together 160 batteries (80 batteries in North America) and your fridge will work again!

Like Share Follow / 10 I used this one weird trick to prove I'm human!

1 orange tank radially on each FLT-800,

We had a thread like this before, which included the option to "Launch It!" and someone makes it in KSP and reports what happened. Anyway, put the 2.5m to 4x1.25m adapter under the pod.

10/10. Only a human would say that, filthy meatbag! I know because I'm a biological human myself, of course.

An ICBM might make orbit with a lightened payload - after all plenty of orbital launchers have been based on missiles. But I strongly doubt it could escape Earth. Randall knows this, that's why he mentions booster rockets.

I've never really had the space for something "serious", but I have just ordered myself a Lego train set. (60051). That counts, right? Sorta?

I deploy some decoy flares to send the missiles the wrong way, then launch drones to chase after the next poster.

The Tupolev Tu-95 "Bear", it's still operated by the Russian air force. In recent years they have been regularly flying close to NATO airspace. And yes, they are LOUD.

The orbital speeds round Earth are much higher than round Kerbin. That's why. But it's off-topic for this thread.

Is there any theoretical speed limit for a scramjet, apart from those imposed by the properties of the materials it could be made of?

Granted. They talk about the co-ordinated assassinations of Barack Obama, Hillary Clinton, and Donald Trump. I wish Valora's battlefield wasn't so bloody annoying.

Granted and granted. The kittens eat up all your poutine. I wish it was 6 pm.

Granted. I wish for another of every food item I own to be delivered fresh to my door.

@kerbiloid That's a really great find! And I think pretty much finalises answering @RainDreamer 's original question, because these unarmed re-entry vehicles are very much like an orbital strike projectile would be, impacting at the same kind of speed quoted as 16000 km/h (or Mach 13, or 4500 m/s). I can't find the mass of the re-entry vehicle, but changing mass should just scale up or down the effects anyway. A bright bolide flying across the sky, then at the impact site a relatively small fireball and a larger cloud of debris thrown into the air, with fragments landing considerably further away. Almost surely an impact crater and probably a blast, but the video doesn't have close-ups or audio to confirm. It's not dissimilar to my prediction on page 3, the biggest difference seems to be that hitting a real-world target throws up a lot more fine dust that lingers, compared to hitting a uniform bed of sand. I think the video also demonstrates that if the guidance was precise enough, an ICBM with kinetic impact warheads would be an effective weapon. Value-for-money is another matter though, and there are concerns that the target and third parties might detect an ICBM launch and assume it was carrying a nuclear weapon and react accordingly.

There's an option buried in the Infolinks to "Unlock All" without having to play through the missions. I've been enjoying the game. It's not exactly what I expected, and I'm not sure I'm all that good at it, but it's certainly challenging and detailed and I'm glad I got it. I doubt I'll put in the kind of hours I've done in Kerbal though, CoaDE doesn't have the same kind of "open solar system" gameplay to it.

On PC, Children of a Dead Earth. It's a great game with some real rabbit holes of complexity. It's not really "Kerbal with guns" like I had expected though - the discrete mission structure and lack of hands-on control gives it a rather different feel. Today I designed a custom railgun, firing a 2.5 gram round at 7.5 km/s (which is faster than any of the stock guns), and tested it out on some drones. Bit of mixed results, the high speed gives it awesome range and sometimes it does great, but other times it seems like the small rounds just pepper the target with holes and don't do much real damage. And the gun is unturreted, because turrets are heavy, but that's making the drones use a lot of rocket fuel to aim. I'm considering switching to a fixed main engine and vernier engines for turning. On 3DS, Pokemon Conquest. Last time I played it I didn't get very far, but I restarted the game and have got more into it. Got some pretty good warriors and Pokemon, and managed to get the hero and Oichi both linked to Rufflets which I'll need to take on the ghost kingdom. Finished a few weeks ago on 3DS, Dragon Quest VI - Realms of Reverie or whatever it's called. Can't go far wrong with a good classic JRPG really, though I do feel it's the weakest of the Zenithia Trilogy. On Android (and on PC sometimes), chess puzzles on Lichess when I have a spare few minutes. I'm distinctly average at them. I often just guess on intuition instead of properly calculated, and I'm prone to overlooking discovered attacks for both sides.

A 90 m CEP is good for a nuke, but it's not so great for a less powerful weapon. For a 10 ton impactor at Mach 10 (with kinetic energy equivalent to its own mass in TNT), the radius to damage "heavily built concrete buildings" is about 20 metres, while for more ordinary buildings it's about 100 metres. I'm not so sure about effectiveness against underground bunkers. Regardless, if you're targeting a reinforced structure you probably want much more precision. Laser-guided bombs can manage a CEP of *one* metre, and probably other systems where the projectile is able to 'see' the target can do the same. Back to the original question of what a rods-of-god strike would look like, well before impact it would probably be just like a nuclear missile re-entry such as this famous(ish) Peacekeeper shot: Although that's a long exposure, I don't know how bright the projectiles would look to the eye.

Gra THIS UNIVERSE HAS ENCOUNTERED A PROBLEM AND WILL BE SHUT DOWN. I wish it was now safe to turn off your computer.

Yeah, if you want the light source on or near Earth, then as per the xkcd results (and the 315 kW power of the Luxor beam) you're looking at a petawatt of power, which is a thousand times global electricity production. Not remotely practical. Better is to put the lasers on the Moon and aim them at Earth. Again based on the xkcd work, a rough guess is that will need a gigawatt or so. That guess can be checked; a gigawatt of green light all aimed at Earth would give about 5000 microlux, and that's about a thousand times brighter than a magnitude 0 star. So if you arranged the lasers on the Moon into a pattern the ones on the lunar night side at least would be easily visible. While a gigawatt is a lot of power, especially since you probably need more like 20 GW electricity to make 1 GW of laser light, it is plausible. Probably about 40 nuclear reactors would do it. Would bulldozers and/or paint be easier? Well the smallest features on the Moon visible to the naked eye are a few hundred km across. That's a *lot* of area to smooth or paint, even if you only need to do it partially. My intuition is that the lasers would actually be less work - yes it requires arranging laser facilities and power generation, and perhaps building long transmission lines (unless you do one power plant per laser), but compared to painting an area the size of a good-sized country it's not so much. If the Moon ever gets extensively colonised, the colony resources could be naturally piggybacked on by a Moon laser advertising project too.

Granted. You all play Orbiter. I wish Orbiter had a good Linux port.

Granted. It was drooling because it has rabies, and a previously-unknown strain of rabies with no vaccination or cure at that. Your cat bites you then runs away. I wish to skip an hour.

Inertial guidance has relatively low precision though. A JDAM bomb has a Circular Error Probably of 30 m with inertial guidance, meaning a 50:50 chance of landing closer or further to the target. And that's with a mere couple of minutes free fall time, a longer flight time worsens the error. Regarding cost, I wonder if a kinetic bombardment platform would necessarily be *that* expensive really. High estimates for the cost of the SLS rocket are $35 billion, let's attribute that full cost to launching the Doomsat and wild-guess developing the satellite itself costs the same kind of money. So $70 billion total or thereabouts. That's a lot by the standards of normal people, it's even a lot by the standards of NASA spaceflight or to the world's wealthiest people. But the US military spends $600 billion *a year*, and expects to spend $1500 billion on the F-35 fighter over its lifetime (OK, to 2070, but still). By military spending standards, kinetic bombardment doesn't look so expensive after all, especially if you can make a program out of it with multiple sats each capable of multiple strikes.

Granted. Donald Trump mind-controls all humanity to be peaceful consumers. I wish the USA had lost its War of Independence.