Undergrad Meteor impact and axial tilt, relation to climate

[cbrons]

I have a hypothetical question. If there was a relatively Earth-like planet out there that somehow experienced a rather catastrophic meteor impact large enough to alter its axial tilt close to 0 degrees, would such an event render the planet essentially a desert world? I.e. there are no more seasons, no more poles, oceans essentially dried up (or would they be dried up?)

Obviously the way the question is worded betrays my ignorance, so forgive me. Thanks for your time.

 

[Droidriven]

I have a hypothetical question. If there was a relatively Earth-like planet out there that somehow experienced a rather catastrophic meteor impact large enough to alter its axial tilt close to 0 degrees, would such an event render the planet essentially a desert world? I.e. there are no more seasons, no more poles, oceans essentially dried up (or would they be dried up?)

Obviously the way the question is worded betrays my ignorance, so forgive me. Thanks for your time.

There would still be poles and it seems to me that there would still be 3 different "seasons" and 1 of them would occur twice in its' year. As it orbited its' Sun, its' "seasons" would change in this order:

1)a season where the north pole would be in full sunlight(potentially no ice cap, not desert, probably a very rainy season) but the south pole would be in complete darkness(potentially frozen for the majority of that season).

2)a season where it receives an even amount of sunlight(mainly) from north to south pole and it would have a normal day and night(potentially a fertile planet during this season, potentially flooding from ice melt from the southern ice)

3)a season where the south pole will be in full sunlight(potentially no ice cap, not desert, probably a very rainy season), north pole would be in complete darkness(potentially frozen for the majority of the season)

4)a season where it receives an even amount of sunlight(mainly) from north to south pole and it would have a normal day and night(potentially a fertile planet during this season, potentially flooding from ice melt from the northern ice)

That's an approximation and without being specific about certain other variables.

It's hard to say exactly because there are atmospheric variables that would have a lot to do with average temperature, temperature ranges which would effect how much ice could form(if any) and how long it would last through the other seasons, how much heat and cold weather patterns could regulate, presence of green house gases, among other things.

 

[newjerseyrunner]

It would cause the climate to be chaotic I would think, not good for any potential life. But early in the solar system, such impacts not only happen, but they're common.

Any life already there during an impact of that scale would likely be wiped out. It's possible in the early solar system that life could be thrown out into space, then rain back down eons later and reseed the planet. It's possible that happened on Earth. Earth suffered many monster collisions in it's time, the biggest theoretically being with an object nearly the size of Mars. Venus suffered an even bigger blow that hit so hard it knocked the whole planet around causing it to spin backwards.

 

[Chronos]

The giant impactor theory is the current favored theory on how our moon was formed. Earth collided with a planet called Theia, returning Earth back to a molten state. Needless to say this delayed the onset of habitable conditions emerging on earth. It is, however, concievable this collision provided the extra nickel iron Earth required to form a sustainable magnetic shield.

 

[|Glitch|]

I have a hypothetical question. If there was a relatively Earth-like planet out there that somehow experienced a rather catastrophic meteor impact large enough to alter its axial tilt close to 0 degrees, would such an event render the planet essentially a desert world? I.e. there are no more seasons, no more poles, oceans essentially dried up (or would they be dried up?)

Obviously the way the question is worded betrays my ignorance, so forgive me. Thanks for your time.

With an axial tilt of 0° the seasons would be determined by the eccentricity of the planet's orbit. The more eccentric the planet's orbit, the more extreme its seasons will be. Furthermore, a large moon can help stabilize the planet's axial tilt. Without such a moon the planet's axial tilt could vary by as much as 85° every few million years. This would cause fluctuations in planet's climate, and may have some effect on life developing on such a planet.

The poles are determined by the planet's rotation, and will always be two for any terrestrial planet. If the planet has a liquid core of molten iron and nickle, then it will also have magnetic poles, which may differ from the planet's rotational poles, as Earth's magnetic poles do. Whether or not there would be surface water would depend on its distance from its parent star. Assuming the planet remains within the habitable zone of its star during its entire orbit, there would be little or no effect on the oceans.

Source:
The Odds for Life on a Moonless Earth
Earth's Stabilizing Moon May Be Unique Within Universe

 

[jim mcnamara]

Here is what appears to be an informed discussion from 2012
http://www.astrobio.net/news-exclusive/loss-of-planetary-tilt-could-doom-alien-life/
With background on a road map to find suitable candidates for exobiolgical investigation:
http://astrobiology.nasa.gov/our-research/astrobiology-at-nasa/astrobiology-strategy/

The first link claims that planets with 0 degree axial tilt would probably not develop life.
The flip side of the argument is here, sort of:
https://arxiv.org/ftp/arxiv/papers/1405/1405.1025.pdf
Tidally locked planets which should be roasted on one side and frozen on the other -- could have life in a sort of 'goldilocks ring' of partial shade.

Maybe @D H has a good perspective. I do not. I think most of this is speculative, or at best shows some models under development.
Anybody else contributing to this thread - PLEASE- cite where you get your information. Otherwise this interesting thread will get locked because speculation is frowned on here at PF.