What would a glassed planet really look like?

Question

While the Halo franchise has used it a lot, other franchises have also mentioned/threatened with the idea of glassing a planet. The sheer heat of the attacks used on the planet to make it uninhabitable would cause the surface to turn to glass.

Now this likely originates from the Trinity nuclear test where they found glass like structures around the explosion site, which they dubbed Trinitite. It is the silicates in the soil heated up so it is likely not an entire planet would be glass, just the parts with lots of sillicates in the ground.

Now what I would want to know is how a “glassed” planet would truly look like for anyone who comes back and tries to terraform it, it is a planet in the Goldilocks zone after all. I would like to know the average surface consistency, how thick the glass would be in places where it does form and what the atmosphere would be like. Some constraints as to what I expect from the glassed planet:

• it was an Earth-like planet beforehand
• It is glassed by primarily heat based weapons, plasma and lasers* for example
• the colonists return to the world 3 years after the glassing happened (can be altered if it is unsurvivable otherwise)
• the planet needs terraforming, of course the colonists will be wearing protective gear outside
• The temperature of the weapons is 3000 degrees.
• All land surfaces that can hold infrastructure are destroyed, the sea’s aren’t specifically targeted.

*lasers of a frequency that interacts little with the atmosphere.

Answer 1

As mentioned above laser weapons would likely not be the weapon of choice to produce this effect at a large scale.

Trinitite is one example of "glassing" or Vitrified sand. Other types are Impactite or Desert Glass. Google image search here and here. And of course lavas.

My expectation would be that areas of actual glassy appearance would be rare and scattered. Requiring specific conditions to be present during the event. On a the larger scale the surface appearance would look closer to impactite. Partly melted clumps and broken mixed angular fragments cemented together. The appearance though greatly depends on how much melt occurs.

Have to point out that, heating the surface to a temperature that would melt rock over a continental or planetary scale to any depth may cause effects that are not readily intuitive. Especially atmospheric effects. You may want to consider breaking your question into separate posts. Having said that, what is the point of glassing the whole surface? The aggressors job is done when all the infrastructure is flattened.

Answer 2

I see some frustration in response to other answers you're getting, but they are correct:

1. The appearance of a glassed planet will depend greatly on how the energy is delivered; particularly in terms of focus, duration, and kinetic byproduct
2. Ship-mounted lasers or plasma weapons, and I'm including Death Star sized "ships" in this, simply cannot generate planet-glassing levels of directed laser or plasma energy without invoking Clarke's third law. By multiple orders of magnitude.
3. Given #2, you will be making up your own methods of directing energy. This is fine. Given #1, the effect will be based on the constraints or potentials of the weapons you are making up. This is also fine. But you can't ask us to give you the realistic specific results of unrealistic unspecified weapons. This is less fine.

In general terms, the longer and more evenly you cook the planet, the more you will end up with a smooth shiny spherical bead. That glassy surface will be as deep as you want it to be, since you are the one making the rules for how long you keep it in the oven. If you gently immolate (?!) the planet by raising it to 3000 degrees (C? you do not specify) the immediate effect will be explosively boiling all liquids and super-heating the atmosphere, which will make one heck of a mess of the surface. Very quickly the elements with lower melting points will melt, and be blown around by the energetic reactions of volatile and vaporizing materials, so things will still be messy even if your heat isn't being applied without any directed force (how? you tell me, you're making up the weapon). After some hours of this (it depends on what your temperature is and how it's being applied), anything that wants to turn into a gas already has and those gases have probably (again, it's your weapon) been stripped away, so your melting rocks can start flowing instead of getting blown around. You'll have a fairly broad window here where the surface crust has more or less the same topography as it did pre-attack, slowly getting smoothed as the high points melt down and the low points fill up. You should expect some volcanic and tectonic activity in places that are already prone to such things as you soften up their plug points, but the vast majority of the surface doesn't have seething pools of magma just itching to burst free if someone delves too greedily or too deep, so you can take your time polishing the planet and get a lovely visual result. The appearance will be much closer to volcanic obsidian/basalt than trinitite unless you stop heating before the melting gets more than a meter or so deep.

Of course, that's the result of a magical microwave oven that's somehow evenly applying heat to the surface (actual microwaves would not work for this purpose). You want directed beams emerging from about 50 ships. These beams will presumably be hooked up to a generator with infinite capacity and arbitrary output, and somehow in the process they do not get hot themselves, nor do the plasma weapons run out of the material they are turning into plasma Plasma is after all a state of matter, which means you are getting mass from somewhere and getting it good and excited before sending it elsewhere. That's fine, perhaps your ships have portals to the Plasma Dimension and feed the waste heat to entropic frost giants. I'm not pointing this out to say that this idea is dumb, but rather to say that your weapons can do whatever you want them to, and your glassed planet can look like whatever you want it to. If you have a specific idea for one and want help with the other in terms of thematic or scientific consistency, we might be able to help-- but we can't just write both sides of the equation for you.

But fine, we have infinite beams of laser/plasma that are 3000 unspecified degrees. This will take a very, very long time to glass a planet. First the energy will be dissipated by the atmosphere, spreading the beam out so it heats a very wide area to a much lesser degree. Assuming implausibly absurd amounts of energy behind the beams, it will still eventually cook off the atmosphere, and the replacement atmosphere that is formed by the boiling of water in the oceans and kindergartens and breweries and forests and whatnot. This will be a potentially extended period of absolute hell on the surface before there stop being people to be bothered by it. Once there aren't so many gases in the way, your surface can start being properly heated. If your beams truly do heat to 3000 degrees, they will only melt whatever they are directly hitting, which will then solidify again as soon as the beam moves on, leaving grooves and trenches at whatever width they happen to be. This might take centuries-- beams are focused and planets are big, after all. It will result in a very lumpy glassed planet that more or less has the same mountains and ocean trenches it did before, but carved with eerie grooves in perfectly straight lines following the orbital paths of the ships. Only rough geography would survive, though-- little if anything manmade would survive the atmospheric boiling, much less the rock-melting.

If you're in a hurry and using focused beams, you can turn them up to 11. But then you're not melting rock, you're vaporizing it. We have a word for "a solid instantaneously becoming a gas": we usually just say "explosion". This vaporized rock will also form a mist (and very quickly a diffuse plasma) that blocks your beams from melting more rock but also makes the immediate area an entirely new sort of cinematic hellscape. You won't get much in the way of smooth glass surfaces with this approach, since the exploding vapor will scatter the melted liquid very violently. You can write rude graffiti on a continental scale fairly quickly with this method, but you'll never get a shiny surface until you run out of crust, which will take either an even longer long time or an even more absurd "how do each of these ships have the power output of a literal star" level of energy.

These are individual examples of very rough principles. Tell us more about how your weapons work and we can tell you what the planet will look like, and how it will change as it cools. Tell us more about what you want your planet to look like, and we can talk about what physics might produce those effects. There's no reason we can't all work together in peace and harmony to destroy your planet and terrorize your galaxy.

Answer 3

Glassing is a surface phenomenon, by it's very nature it will have little effect deeper into the ground. If you simply melt the surface of the planet you get basalt, not glass. Glass happens with flash heating followed by very rapid cooling. Very high energy, very short duration. Nukes, rocks that blow themselves to bits in the atmosphere etc. It also requires the right conditions on the ground. "Glassing the planet" might be an expression but it won't actually happen. You don't see glass craters from nuke tests.

Answer 4

I'm gonna start with nukes, because focused attacks like lasers wouldn't have the glassing effect you're looking for.

There are a few scenarios.

If you set off enough nukes to cover the surface all at once, it would blow most of the atmosphere into space, vaporize the top three meters of ocean, and surround the planet with a layer of hot gas. I can't calculate exact time scales, but for the first few weeks, the surface would get pelted by silicates and metals freezing and falling like ash. In a period of years, most of the carbon-based ash would fall out. In a period of decades, the water would precipitate out, then freeze. Without the original atmosphere acting like a blanket, the planet would turn into an airless, frozen husk covered in ice.

If you set off the bombs like a wave, you could keep most of the air on the planet. A two thousand degree blast of air would scour the surface at hundreds of miles per hour, preceding the bombs that will keep it moving. The force of the wind would scrape the surface clean before the bombs melted the underlying rock. The wind would rip the rough parts off of mountain ranges. It would vaporize the top layer of ocean and choke what's left of the oceans with debris. This model would take even longer to cool off, but in this case the heat would dissociate the water's elements, and you'd launch a large amount of dissociated hydrogen into space. The dissociated oxygen would combine with carbon, creating a Venusian greenhouse.

All said, you're going to have to spend tens of thousands of years re-terraforming the planet either way.

Answer 5

This is a fascinating question and is very complicated to answer, and depends on quite a few factors. The things I will attempt to cover in this answer are:

What would soil look like?

What will happen to cities?

What would the atmosphere look like immediately after the glassing occurs?

Answering this question does require a few assumptions, and for the sake of simplicity I will take everything you say at face value. I am working on the assumption that by the weapon's temperature you mean how hot the target becomes. I will also assume that in "land that can hold infrastructure" you include largely uninhabited areas, like deserts and arctic regions.

The first dependency is whether 3,000 degrees is in fahrenheit or celcius. The result will depend heavily on which measurement is being used, and I will try to include both. It does also depend on how long the weapon remains on the target, I will assume long enough to heat everything until the bedrock up to 3,000 degrees, also accounting for fahrenheit and celcius.

For the sake of my own time (and sanity) I won't be going into every aspect of it, and as of writing this it took me roughly an hour to just figure out what clay would look like post-glassing.

If I don't cite a source, it was something I could figure out through a few google searches (I'm not saying that to be demeaning, this still took a long time and I fully do not blame you for asking instead of doing this yourself)

Now for the actual answer:

When it comes to soil, this actually depends on 3 things itself: the composition in amounts of clay, silt, and sand.

Clay first: the chemical composition of clay is such that when it is heated to ~1,200 celcius, or ~2,200 fahrenheit during the firing process, it shrinks and releases H2O into the air. At ~1400 celcius or ~2250 fahrenheit, the most common type of clay (Kaolinite) will decompose into what is described as "mullite-like glass" (source 1), a cloudy white stone.

Now onto silt:

Seeing as silt is just eroded rock, I feel more confident in less in-depth research, along with the fact that saying exactly what silt would become is nearly impossible, and would be drastically different based on the precise location, so instead of focusing on the exact chemical composition of the rock like I had to do with clay (as I couldn't find any studies where they heated up clay to 3,000 degrees) I will simply focus on silicate rocks as a whole.

Thankfully (For the sake of my sanity) the heat of the lasers is enough to melt all silicates within rock at about 1200 celcius or 2200 fahrenheit (source 2). These would cool into extrusive igneous rocks, such as basalt or obsidian. Since obsidian requires near-instant cooling, it would mostly be slower cooled rocks like basalt or pumice, especially pumice considering that the melted soil would likely have a high water content (even more so in silty clay).

The final soil type is sand: sand is also made primarily of silicates, so would likely give glassy rocks such as trinitite, with a more greenish hue than the usual black landscapes.

Depending on the measurements, much of the ground would actually be vaporized. If it's in celcius, the boiling point of silicon is around 2900 celcius. It wouldn't be an explosion, but the lava would be boiling. If the measurement was in fahrenheit though, it would only be enough to melt, not vaporize. The vaporization of the stone would put countless deadly chemicals, including heavy metals, into the air, making it inhospitable to anything but the hardiest of microorganisms for decades, likely longer without extensive terraforming efforts.

Onto the next question, what would happen to cities:

For this I am going to assume the buildings are made similar to buildings on earth, made of concrete and steel. Concrete has a melting point of around 1500 celcius, or around 2800 fahrenheit, but it can go up to almost exactly 3000 fahrenheit, or 1650 celcius. the melting point of steel varies a lot depending on what kind, but all of them are under the temperature of the weapons provided. Given that, cities would essentially become large piles of melted concrete and steel.

The final question, the atmosphere:

Because of the fact that the given temperatures are more than enough to instantly combust any kind of organic matter, the soot that would enter the atmosphere would be akin to a nuclear winter. These are hypothesized to last several decades, so your colonists would likely have to wait quite a while before life can become sustainable for them. Considering the advanced technology required for glassing I don't doubt the ability to purify the air in whatever they live in, the issue would more be of electricity. With nothing to burn, and all previously existing rivers being reduced to slightly lowered divots of volcanic rock, and the sun being blocked out, electricity would be a huge concern. Anywho, back to the actual question-

The atmosphere would be largely unlivable for almost any sort of complex life, due to soot in the air and the toxic chemicals that would likely be released by the melting stone and burning plants. The temperatures would also likely remain dangerously hot for a very long time. It's also worth noting that despite the fact that oceans are not targeted in this scenario, the winter would decimate the oceanic ecosystem, just like it did after the chicxulub impact.

It really doesn't need to be said, but any permafrost the planet may have had is now gone. If the weapons targeted the arctic regions, then the ice was vaporized in moments. If they didn't, it was melted by the heat of the ground entering the atmosphere. Either way, all of the history and information that was stored in that ice, along with the CO2 and soot from past eruptions and such are all released into the water and into the atmosphere, acidifying the oceans even more with the worldwide fires and poisoning them with soot.

In conclusion:

Most of the planet would be black volcanic rock. Deserts could consist of more greenish rocks like trinitite. Areas with a high clay content would be more grayish. The atmosphere would be full of silt for decades, blocking out almost all light while also trapping in the heat from the lasers, keeping it dangerously hot for a long time, possibly for anywhere from years to decades. Cities would be turned to misshapen hills of concrete and steel. Life on land would be set back billions of years, likely only the hardiest extremophiles surviving. Any mining operations would be dangerous for months to years after the glassing while the lava cools. And the soot in the air would be very bad for the morale of any colonists. Even the oceans are mostly dead, collateral damage of the complete and total collapse of the energy cycle and poisoned by the fires and incinerated life across the world.

I hope this answers your question, and you're more than welcome to ask for clarification, more information, or exploring a different aspect. This question was genuinely a lot of fun researching!

Sources:

Source 1: Luo P, Tang Y, Li R, Ju M. Effects of Minerals Type and Content on the Synthetic Graphitization of Coal: Insights from the Mixture of Minerals and Anthracite with Varied Rank. Minerals. 2023; 13(8):1024. https://doi.org/10.3390/min13081024

Source 2: Melting Points of Rocks and Minerals. (n.d.). http://hyperphysics.phy-astr.gsu.edu/hbase/Geophys/meltrock.html

Answer 6

Something always survives, something always thrives.

The biosphere of a planet goes kilometers down and bubbles back up in hot geysirs and moving rock.

So the evaporated oceans rain down on hot obsidian, collecting at some places, seeping below at others hollowing out halls and caves below, natural hot houses.

Within it regrows the thinned out remains of a once mighty biosphere. Plantseeds, swept away and then burrowed in muck under lava, spores that survived in the atmosphere, seeds even a lonely bird might have carried away from the blast wave.

Given the radioactivity, evolution is fast, harsh and distinct. There is a outside biome, rewarding flying predators, and a inside biome, rewarding speed, heat-resistance and the ability to slither through razorsharp cracks.

Answer 7

I'll take the liberty to also design the weapon, since you didn't specify details of how it works:

Rather than attempt to melt the planet's entire surface up to a certain thickness, like other answers want to assume, I would instead blow up the piece of continent where sandy rocks are most prevalent, causing a storm of molten glass to rain down over the rest of the planet.

It would look like ... a thick glaze. Made of glass.

• In the oceans and lakes, the glass would sink to the bottom.

• In the poles, it would melt the ice caps, and then sink to the bottom.

• In the deserts, it would settle as a clean sheet of glass.

• Everywhere else from forests to cities, it would cause fires and then settle in somewhat messier form, mixed with debris. Additional molten glass drops returning from orbit after the initial explosion or a follow-up hit would then create a more uniform glaze over the ashes.

Terraforming would consist mostly of using explosives and bulldozing robots to remove the glassy layer, probably starting in food-growing areas.

This is obviously inspired by the Chicxulub Event and the K-T boundary, with a key difference being that a sci-fi weapon can be designed to achieve effects that a dumb rock couldn't.

Answer 8

Assuming "glassing" as in an attempt to melt at least the exact surface, and assuming it was by direct heat transfer to the ground (attempting to bypass the atmosphere)...

This depends on time

In order to melt the top 1m of surface of Earth, one needs to apply excess energy which is pretty hard to calculate, as the surface is composed of varying minerals, organics and there's also a lot of water on and within the surface. Let's assume that all surface is in fact rocks (granite and others), then taking this paper as a base, and estimating top figures, the energy needed to hit the ground is 1500*1793*2689 = 7.232e9 J/m^2 (plus another 580e3*2689 or 1.559e9 J/m^2 if fusion is in effect. Better use the plus for estimates, so the total is 8.791e9 J/m^2). The used rock's (peridotite) heat conductivity is in order of single W/(m*K), thus if we'd apply this energy to the surface quickly, the upper thin layer would vaporize or plasmatize, blocking the energy flow to the surface and absorbing all the rest of incoming energy flux, likely ablating next layers by plasma interference, and also emanating most of the incoming energy back into space as blackbody radiation.

So, if the required heat is applied at speed faster than about 1e7 W/m^2, the outer layers would not be able to transfer excess heat into the lower layers fast enough, would vaporize and cause plasmatic effects to the surface. The resultant surface would look glassy, but it would be covered by volcanic ash, with amount depending on exact composition of the planet, including water-covered areas. The seas would likely remain, or at least won't all vaporize and eventually precipitate back from heated atmosphere.

If the target energy would be delivered at rates about 1e6 W/m^2, this would involve largely unpredictable interference with water vapor, together with burnt organics, volcanic-like ash produced by molten ground, creating an opaque atmosphere that would start intercepting the incoming energy flux, heating up and producing similar, but limited to gaseous compositions, effect over the surface. Also, with this in place, the atmospheric changes would be able to be reacted upon by those that were "cooking" the planet, with one probable decision of prolonging the process at the same power rates, increasing the payload delivered to the surface, in order to ensure that the top layer of the planet is indeed melted. But this process would not allow the planet to cool down quickly enough after all this heating, so the glass layer would not form; instead, the planet would be covered by volcanic minerals like granite, topped with organical ash resulted from burning and then condensing of all the carbo-hydro-nitro-whatever stuff used by the wildlife in its daily proliferation. The planet should still be able to cool down within three years, however the exact temperature depends on its atmospheric composition and whether its upper layers would not, or would stop being an obstacle to NIR/red light of blackbody radiation.

If the energy would be delivered at rates less than about 100 kW/m^2, the surface would burn, but the volcanic rocks would not reach the melting point, because at these power rates the equilibrium temperature would be a tad lower than required to melt those minerals. Organics would still get burned, forming ash-filled atmosphere, the gaseous layers might start absorbing the incoming flux and getting ionized, yet the plasma would not be able to reach serious temperature due to radiation cooling, so the planet would "just" become covered with ash, with its rocks exposed where there would be high winds, but nothing resembling glass would form on their surface.

PS: Your data of "weapons having temperature of 3000C" allow for enough of them to cook the planet; yet even if all visible sky would be covered in heaters of 3000C, it would only be able to heat the planet to 3000C, and the influx would be as high as blackbody radiation of a body with this temperature, or 6.5e6 W/m^2, leading to the second scenario. With this kind of weaponry, you won't vaporize the surface, but depending on how long would you cook the planet, you might not have a glassy crust, but instead would get solidified lava under volcanic and organic ash.

This also depends on energy

As it's known, you can deliver enough energy to the celestial body to make parts of it overcome the gravity pull of the rest, and thus make the planet explode from sheer temperature; however the powers required to do that are many orders of magnitude higher than those required to "just" glass it over, or cook in an oven, whatever would happen. But, assuming those cookers to desire not to waste excess energy into this universe, such an extremity should be counted as not happening.

Still, there is an order of energy delivery that would happen to leave the planet in molten crust state, as mentioned in other answers, which is about 4 orders of magnitude greater than melting a single meter of surface. If that much is transferred to the planet, it would first be bright as a white dwarf due to sheer heat of the surface, would also lose all its water, so no more seas even if there were, it will grow dimmer over time after the heating would cease, yet due to all crust getting molten it would not allow landing for good several thousand years, until the amount of heat stored under the first kilometer below the surface would subside to the point of crust to solidify again, somewhere.

On the other side, the heating could be shorter together with making the flux lower, like a flash or brief exposure to a superstrong energy emitter. A delivery of 1e6 J/m^2 over a period of a microsecond or below, assuming frequency that is absorbed in the atmosphere at 1% or less, and absorbed by a thin layer of ground at 50%, would cause quite an interesting behavior, specifically, hitting a condition named Warm dense matter, the physins of which is still under development, as its condition could at least be two-fold. Predicting which state would the surface get after such an exposure is out of my limits. Anything above, and you're seeking a scientific grant to fund the answer yourself.