Planet Without Seasons?

[scotpens]

Life on Earth is tied to the cycle of the seasons. And we all know that our planet has seasons because of the tilt of its axis. What about a planet whose rotational axis is perpendicular or near-perpendicular to the plane of its orbit? What would climate conditions be like on a seasonless world? What kind of life, if any, could be expected to evolve there?

 

[MacLeod]

Doesn't Mecury only rotate only about twice per Earth year? and I also believe that it has a negliable axial tilt of >1%. But if we are talking planetary rotation as well as axial tilt , would there be enough gravity without a decent day/night cycle to hold a liquid surface.

But we are talking about planets in goldilocks zone, I would say that if life did evovle on it you might get more life that is more adpated to living in one region. No migrater birds/animals etc..

 

[SilentP]

Also you could expect a difference in how certain life forms would grow and mature. For example, you wouldn't have vegetation that act seasonally (i.e. shedding leaves/furs for winter). Also reproductive cycles would perhaps only when resources are suitable for creatures, rather than to be the onset of colder months etc.

 

[scotthm]

What would climate conditions be like on a seasonless world?

Seasons are just one of many variables that could affect climate on any given part of a planet, so I would say the range of climate possibilities is not diminished by the lack of seasons.

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[MacLeod]

^tre but each region wouldn't see a change in climate it would always be the same, warmer at the equator getting cooler as you head towards the poles

 

[scotthm]

^tre but each region wouldn't see a change in climate it would always be the same, warmer at the equator getting cooler as you head towards the poles

The absence or presence of oceans, the distribution of landmasses, volcanic activity, mountain ranges, length of day, orbital eccentricity, etc. may all affect climate over time on a dynamic planet. Just because there may not be seasonal climate change doesn't mean that climate is static. There are too many unknown variables to answer the question posed in the OP.

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[sojourner]

It's answerable if you take the question as a simple hypothetical.

 

[MacLeod]

Yes but random events such as a volcanic eruption are just that random. If you wanted to you could factor into tectonic activity. Is the atmosphere prone to high/low pressures. What's the pressur of the atmosphere. There are many things you could factor in.

With only 1 referrence planet thats has life and seasons. i.e the Earth. A way to answer his question would be to consider what the Earth would be like if it a negliable tilt. Instead of the =/- 33% it has.

 

[scotthm]

A way to answer his question would be to consider what the Earth would be like if it a negliable tilt. Instead of the =/- 33% it has.

Eternal spring. That could be nice.

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[scotpens]

. . .With only 1 referrence planet thats has life and seasons. i.e the Earth. A way to answer his question would be to consider what the Earth would be like if it a negliable tilt. Instead of the =/- 33% it has.

Approximately 23-1/2 degrees (not percent), actually. Unless those bastards have gone and shifted the tilt of the Earth!

 

[sojourner]

^Superman did it, he's a dick.

 

[MacLeod]

^^My error

 

[John O.]

If we had zero tilt, I believe there would still be variation in the year-round temperatures based on the slight eccentricity of the Earth's orbit - but it would be way less drastic than the difference between winter and summer and there'd be effectively no definable Spring or Fall.

 

[MacLeod]

Would that depend on where you are though John? As the tilt gives us the seasons. So In the more northely and southerly latitudes wouldn't their weather be more akin to Spring/Autumn than Summer/Winter as those places would never tilt towards the sun or away from the sun?

 

[Shatnertage]

Why does the question make me think of this?

The rich and sunny planet Ursa Minor Beta has the quite peculiar property that most of its surface consists of subtropic coastline. Even more peculiar, on this world it's always Saturday afternoon, just right before the beach bars close. Light City, the only city on Ursa Minor Beta, which can only be reached by plane, is the very place where the editorial offices of The Hitchhiker's Guide to the Galaxy reside. A further anomaly in Light City is that the Lalamatine district, just behind the beach, is the only place on the planet not to enjoy a perpetual Saturday afternoon. Instead it is always early evening, with cooling breezes - this is where the nightclubs are located.

Places in the HHGTTG

 

[scotpens]

^^ Cute. But Ursa Minor Beta is a star (Kochab), not a planet.

 

[John O.]

Would that depend on where you are though John? As the tilt gives us the seasons. So In the more northely and southerly latitudes wouldn't their weather be more akin to Spring/Autumn than Summer/Winter as those places would never tilt towards the sun or away from the sun?

Above and below the equator would be cooler year round, yeah, but from Jan 1 to Jan 1 of the next year, they would see the same gradual temperature increase as we approached perihelion and then decrease as we moved further out just like the equator, the average temp would just be lower.

 

[MLJames]

Would that depend on where you are though John? As the tilt gives us the seasons. So In the more northely and southerly latitudes wouldn't their weather be more akin to Spring/Autumn than Summer/Winter as those places would never tilt towards the sun or away from the sun?

Not really. Because of the eccentricity of its orbit, the Earth gets about 8% more sunlight at its closest approach than at its farthest. With no axial tilt, the entire surface of the world would experience that same percentage of change.

Think of it this way. Mount two 100 watt light bulbs above a surface. Make sure both bulbs are connected to one dimmer switch. Focus one straight down so that it makes a circle with an area of 10 square centimeters, and the other at an angle which makes an ellipse with an area of 20 square centimeters. Each bit of the ellipse is receiving half the light a corresponding area on the circle receives.

Now dial down the bulbs to 50 watts. The amount of energy each square centimeter on either figure is receiving is less, but the percentage difference between the circle and the ellipse remains constant.

That's what happens on the Earth without an axial tilt, except the difference in angles is caused by the curvature of the Earth. With a vertical axis, there's no way for the obliqueness of the sun's rays at higher latitudes to shift as the Earth circles it. The percentage difference between the equator and, say, Oslo is always going to be the same throughout the year. The only variable is the intensity of energy at any given distance from the sun.

 

[scotthm]

The only variable is the intensity of energy at any given distance from the sun.

Really? You don't consider the Earth's rotation, cloud cover, volcanic activity, solar output, etc. to be "variables"?

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[sojourner]

^Not for the terms of his hypothetical situation.