Live data from Hacker News

What made Earth a giant snowball 700M years ago? Scientists have an answer

sydney.edu.au

21–30 of 193 posts

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#21

There is a fantastic BBC Horizons documentary from the 90s called Snowball Earth that was easy to find on YouTube the last time I looked, but just now I see a hot mess of search results and if it's still in there somewhere I can't find it. EDIT: found it on dailymotion and its a great story of how the radical theory was rejected then accepted. https://www.dailymotion.com/video/x7o0b66

First result from Kagi. https://www.dailymotion.com/video/xw5nro

     (am also annoying about Thinkpads, FreeTaxUSA)

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#22
post #5

Earlier quoted context omitted.

Have you done the calculation how much material is required for such an endeavor? I bet there are more cost effective approaches.

Okay, like what exactly?

This is dangerous talk. Aliens might be crawling HN and feed their AI models to find our weak spots! Beware.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#23

Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.

You have to make sure it doesn't drift away from the Langrange point, which is unstable…

Well, assuming an alien species that can deal with interstellat travel I am sure they can figure out a way to stay at a lagrange point.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#24
post #5

Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.

Have you done the calculation how much material is required for such an endeavor? I bet there are more cost effective approaches.

It doesn't have to be very thick at all. Harder part would be to keep it in place, as it would act as a sail.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#25

Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.

They tried that with the moon but parked it in the wrong spot.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#26

Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.

Or you could just smack it with a really big rock. That nicely sterlizes the planet too, so you can reseed it with life from your planet after to make it more comfortable.

Honestly it's all kind of silly because distances are so vast. It makes little sense to travel to a distant star - much better to build space habitats in your own star system. And even if you were going to do that for some crazy reason, there's no shortage of uninhabited planets out there. There's no need to commit planetary genocide of an alien race. Also if you have that kind of tech level, space habitats make more sense than planets anyway. Finally if you seed distant star systems with your own species, you risk that species going to war with you later (see how that played out on Earth just across the oceans.)

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#27

Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.

I can’t believe I remember this. You jogged an old memory of Angry Beavers loose. IIRC in one episode they were tasked to save the day Armageddon style but started getting pulled into the sun because they strayed too far into its gravitational field and couldn’t boost out. So the beavers went out and built a dam in space to block it, which saved them but then Mission Control calls them up and says they’ve launched a new ice age.

This is all from memory and frankly I’m finding it fun trying it recall it without confirming it haha

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#28
post #16

Earlier quoted context omitted.

Better than nuclear weapon, no nasty fall out. Better than death star, you still have a planet afterwards.

If they had made the death star bigger, they could have done this tbh.

Wouldn't moving the death star closer to the sun sort that out ?

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#29

Seems like a low risk approach for taking over a planet would be to just park a large shade between the planet and it's star then let it enter a deep freeze. Then you could just remove the shade and let the planet warm back up before settling down.

That'd make for a good story setup: aliens park a shadeship (c) at L1 and wait. They block out most but not all of the sun. After some time (months? years?), conditions on Earth become unbearable, so earthlings have to mount an attack. Kind of like the movie Sunshine, but with more believable physics. Edit: as a bonus, it could take place in ~50-100 years, when global warming has gotten worse. The aliens could disgui…

Love this idea for a story.

As an alternative - it could be the oil producing countries, not aliens - seeking shade earth to disrupt solar and wind energy, and return to oil dominance.

Re: What made Earth a giant snowball 700M years ago? Scientists have an answer

#30

So, Ice Ball or Venus. Seems like climate is more sensitive than we think. Man made impact or not, the whole system seems on a knifes edge of tipping towards the extremes. That we are living right now is rare in-between point.

Keep in mind that becoming an ice ball likely led to significantly increased biodiversity, via Wikipedia:

> Since 2009, some researchers have argued that during the Cryogenian Period, potentially the oldest known fossils of sponges, and therefore animals, were formed. However, it is unclear whether these fossils actually belong to sponges, though the authors do not rule out the possibility of such fossils to represent proto-sponges or complex microbial precursors to sponge-grade organisms. The issue of whether or not biology was impacted by this event has not been settled, for example Porter (2000) suggests that new groups of life evolved during this period, including the red algae and green algae, stramenopiles, ciliates, dinoflagellates, and testate amoeba.

> The end of the period also saw the origin of heterotrophic plankton, which would feed on unicellular algae and prokaryotes, ending the bacterial dominance of the oceans.

Even during catastrophic events, life persists in certain niches: deep sea life usually flourishes during massive extinctions because the marine snow becomes a blizzard; ducks survived the dinosaur extinction because rivers obtain bioavailable energy from gravity and erosion, not photosynthesis. So I suspect something like an "Mars vs Venus" cycle is necessary for the evolution of complex life. A highly predictable habitable planet might have cyanobacteria but not algae, since there wouldn't be any selective crises for mutated bacteria to adapt to. It would be awfully hard for a spectrometer to tell the difference between a planet full of bacteria and a pre-civilization planet full pf complex life.

[1] https://en.wikipedia.org/wiki/Cryogenian

Post reply on HN