Tag Archives: Earth

Existential risk simulator: throw asteroids at the Earth

Had a bad week? Or just simply looking for a way to kill time at work as the year winds down? How about simulating asteroid collisions with the Earth? [via Space.com]

Just to get the disappointment up front: you don’t get a Hollywood CGI rendering of your imaginary impact (though there is a sort of intro video of a rock falling into the gravity well that runs while the calculations are being done, a bit like a cut-scene from Bruce Willis Saves The Planet While Wearing a Grubby Wifebeater Vest: The Computer Game or something). But what you do get is a list of statistical stuff: energy released in impact, crater size, thermal radiation, that sort of thing.

So, a pretty decent tool for doing the worldbuilding due diligence on your apocalypse novel… or simply exercising your inner misanthrope (fluffy white lap-cat and hammy accent optional).

Blueprint for a Dying Earth: what would happen if the world stopped spinning?

I’m not sure whether I’m a sucker for outlandish “what if?” speculation because I’ve always read science fiction, or whether I read sf because I have some innate speculative itch that I need to scratch. Whichever it may be, this is the sort of thing that pushes a whole lot of my buttons: using modelling software to determine what Planet Earth would look like were it to – for some reason – stop spinning [via BoingBoing].

The lack of the centrifugal effect would result in the gravity of the earth being the only significant force controlling the extent of the oceans. Prominent celestial bodies such as the moon and sun would also play a role, but because of their distance from the earth, their impact on the extent of global oceans would be negligible.

If the earth’s gravity alone was responsible for creating a new geography, the huge bulge of oceanic water—which is now about 8 km high at the equator—would migrate to where a stationary earth’s gravity would be the strongest. This bulge is attributed to the centrifugal effect of earth’s spinning with a linear speed of 1,667 km/hour at the equator. The existing equatorial water bulge also inflates the ellipsoidal shape of the globe itself.


Today, all three world oceans are connected. This creates a global ocean with basically one sea level. As a consequence of rotational slowdown, the outline of the global ocean would continuously undergo dramatic changes. Equatorial waters would move toward polar areas, initially causing a significant reduction in depth while filling the polar basins that have much less capacity. As regions at high latitude in the northern hemisphere become submerged, the areal extent of the northern circumpolar ocean would rapidly expand, covering the vast lowlands of Siberia and northern portions of North America. The global ocean would remain one unit until the rotation of the earth decreased to the speed at which ocean separation would occur. The interaction between the inertia of huge water bodies and decreasing centrifugal force would be very complicated. As the consequence of steady slowdown of earth’s rotation, the global ocean would be gradually separated into two oceans…

Sure, so it’s pretty unlikely to ever happen… and if it did, speculating about topography would be the last of our concerns, I imagine.

But what if…?

[ As a side note, that’s a great way to virally advertise a piece of software that would otherwise only be of interest to 0.001% of the world’s population. Kudos! ]

Earth and other unlikely worlds

Apologies to Paul Mcauley for pinching the name of his blog for a post title, but it felt appropriate!

In addition to raking over our old friends the Drake Equation and the Fermi Paradox, COSMOS Magazine looks at the possibilty of the sort of planets found in classic space opera actually existing… you know the sort, solid globes of diamond or iron or ice or whatever else.

THE EARTH FORMED in a region of the Solar System’s protoplanetary disc that was relatively rich in the element oxygen. So on top of an iron-rich core, our planet is mostly built out of oxygen-containing silicate rocks. But further out in the protoplanetary disc, the ratio of the elements carbon and oxygen was probably different.

A class of meteorites found on Earth, called enstatite chondrites, may have formed in this region – they have a ratio of carbon to oxygen that is a thousand times larger than the ratio found on Earth.

“If an entire planet were to have condensed from this kind of raw material, it would have ended up enormously different from the Earth,” says Marc Kuchner, an expert on exoplanets at NASA’s Goddard Space Flight Centre near Washington DC.

Built out of relatively more carbon than oxygen, such a planet would still have a metallic iron core, but the outer layers could be composed of ceramics – silicon and titanium carbides – with a shell of pure carbon on top.

These ceramics and graphite would make the entire planet extremely hard and heat-resistant, and it could survive much closer to its star. Even more bizarre is that the high pressure beneath the surface would convert the bottom of the graphite layer into an entire shell of diamond that would be many kilometres thick.

That’s your sensawunda fix for the day, I reckon. And if you’re a fan of the OMG-we’re-so-insignificant angle, try this for size: Earth’s habitable period may nearly be over, at least on a cosmological time-scale [via SlashDot].

“The Sun does not seem like the perfect star for a system where life might arise. Although it is hard to argue with the Sun’s ‘success’ as it so far is the only star known to host a planet with life, our studies indicate that the ideal stars to support planets suitable for life for tens of billions of years may be a smaller slower burning ‘orange dwarf’ with a longer lifetime than the Sun ― about 20-40 billion years. These stars, also called K stars, are stable stars with a habitable zone that remains in the same place for tens of billions of years. They are 10 times more numerous than the Sun, and may provide the best potential habitat for life in the long run.”

Take that, Rare Earth Theory! Turns out we’re not so special after all… though whether that’s reassuring or depressing is a matter for debate.

Kim Stanley Robinson on why space is a bad idea… and a good idea

Planet EarthSpace exploration tends to be a black-and-white debate, with interested parties falling into either enthusiastic advocacy or strident denouncement. But as with most things, there’s a considerable middle-ground to explore – and over at the Washington Post, Kim Stanley Robinson brings the humanist pragmatism as he argues that space exploration is a worthy goal provided it helps us become a species that doesn’t have its finger hovering perpetually over the self-destruct button:

Eventually, if things go well on Earth, we may begin to inhabit the moons and planets of the solar system more completely, with populations living their entire lives off Earth. At this stage, Mars will always loom as the best candidate for a viable second home. If we alter that planet by importing Earth’s organisms into a rehydrated Martian landscape, that would make it safer for us to live there long-term. These big possibilities, described at length in my Mars novels, will make the planet one of the best 22nd century answers to the question, “Why space?”

And later, if things are still going well on Earth — always the necessary condition — we might live throughout our solar system. This civilization would be a great thing, as a healthy Earth would have to exist at its heart. But given all we have to do first, the full flourishing of such a civilization is surely centuries away.

So why even talk about this? Because it is useful to take the long view from time to time. This is what science fiction does, and though science fiction has been bad about space, it has been good about time. Taking that long view, we no longer seem like the most sophisticated culture ever; indeed, much that we do now will look silly or even criminal in the future. The long view also reminds us that we are a species only about 100,000 years old, evolving on a planet where the average lifetime of a species is 10 million years. Unless we blow it, humans are going to be around in 1,000 years — and if we make it that far, it’s likely that we’ll last much longer than that.

So, what actions, taken today, will help our children, and theirs, and theirs? From that perspective, decarbonizing our technology and creating a sustainable civilization emerge as the overriding goals of our age. If going into space helps achieve those goals, we should go; if going into space is premature, or falls into the category of “a good idea if Earth is healthy,” it should be put on the science fiction shelf, where I hope our descendants will be free to choose it if they want it.

What do you think? Is escaping the gravity well a means to an end in itself, or should we concentrate on tidying up our own back yard before heading out into the local neighbourhood? [via BoingBoing; image courtesy NASA]