Launch Pad #3: A question

July 28, 2010

I want to run a little experiment.  (You see?  Science!)  I’m going to ask a question, and I want you to answer in the comments without reading any of the previous answers, and without googling it.

Question:  What causes the seasons?

69 Responses to “Launch Pad #3: A question”

  1. Gathers Scrolls Says:

    The gradual tilting of the Earth on its axis, as it revolves around the Sun, causing different parts of the Earth to be closer or farther away from the Sun.

  2. Taylor Says:

    Axis tilt is the reason for the seasons! ^___^ Or I hope that’s right…

  3. wygit Says:

    The equator not being parallel to the Earth’s orbit.
    (Or, you could say, the Earth’s axis not being perpendicular to its orbit…)

  4. Mark Hibshman Says:

    Isn’t it the planet’s axis as it travels around the sun? Tilting the “top half” of the planet towards/away from the sun as we follow our elliptical orbit?

  5. Steven Says:

    The tilt of the earth on it’s axes

  6. jon spencer Says:

    Either the Flying Spaghetti Monster or the tilt of the axis.

  7. Christine M. Says:

    Positioning of the sun and the earth and the planet spins on its axis? Or something like that. *g*

  8. Variation in solar heating caused by the fact that the Earth’s axis of rotation isn’t perpendicular to (or in) the plane of its orbit. I forget if differences in the length of the day dominate the change in cross-section (= area presented perpendicular to the Sun).

  9. From what I recall, it’s because the Earth is tilted on its axis. As it revolves around the sun, it’s at a different angle, so the rays of the sun hit at a different strength. So when the North Pole is farther from the sun, the rays are weaker, mean the air doesn’t get as warm, and we have fall and winter.

    As another interesting fact, for those who don’t already know, trees don’t grow above a certain latitude because the sun rays are too oblique, and there aren’t enough photons to process photosynthesis.

  10. Margaret Says:

    The angle of the earth on it’s axis coupled with the distance between the earth and sun at any given time causes seasonal changes as the earth moves around it’s orbit.

  11. Toby Says:

    Seasons are caused by the tilt of the earth on its axis and the roundness of the earth. For part of the year, the northern hemisphere gets more sunlight for a longer day, more heat is generated and you have summer. For the other half of the year you get less sun, shorter days, and get winter. Not much of seasonality near the equator, not much variation in temps compared with higher latitudes. The earth wobbles due to imperfect roundness, so you get a few more days of summer in the southern hemisphere.

  12. John Shearer Says:

    I was going to go all “Balderdash” on this question with an answer like : “Oh, the seasons are a result of how the rotation of the Earth and its distance from the sun cause the weather to change resulting in the creation of the seasons.” Instead, I’m going to go with the smart-alecky: “Because the calendar says so.”

  13. Eloise Says:

    Axial tilt is the short answer to your question btw. It causes the changing lengths of day and thus the seasons. Only relevant if you live outside the tropical regions though.

    But it’s not science, it’s education. Science would have a hypothesis, a means to test it (aka the experiment) and then an analysis of the test to see if it proved the hypothesis, disproved it, or wasn’t clear.

    The science approach might look like: my readers are more likely to know what causes the seasons than readers of the twilight author’s blog. So we will both ask the same question and compare proportions of correct answers to test this.

  14. shadowcat Says:

    earth moving closer and further away from the sun?

  15. Re Williams Says:

    The tilting of the earth on it’s axis during orbit.

    When the northern hemisphere tilts towards the sun it’s summer in the north with the midnight sun above the Arctic circle.

    When the southern axis tilts towards the sun it’s summer in the southern hemisphere with 24 of sun for the penguins in the Anarctic. (Sorry spell check can’t find ‘Anarctic and I’m at a dyslexic loss at the moment.)

  16. MQH,Himself Says:

    Earth axis tilt gives different access to solar, as the earth travels around the sun.

  17. Casey Says:

    Trouble with wordpress is that its damned hard NOT to read/see the prior answers to scroll to get to this lil’ input box. 😉

    Axial tilt (earth wobble) as we roll our merry way about the sun gives us seasons. Either that or pink pixie dust from the moon fairies. 😀

  18. Zita Says:

    The earth turning around the sun. The earth is on a slight tilt. Sometimes the north pole is closer to the sun (winter in the northern hemisphere). Sometimes the south pole is closer (summer in the northern hemisphere). Our circuit around the sun is not a perfect circle either, it’s more of an oval. During winter in the northern hemisphere we are actually the farthest away from the sun, so even though the north pole is closest to the sun, it’s winter because we are the farthest away.

  19. Stephanie Says:

    The angle of the sun changes as the Earth revolves around the sun while titled on its axis.

  20. Edward Says:

    Small gnomes in the earth slowly rotate the earth to change the seasons.

  21. Debbie W. Says:

    Well, let’s see. I always hear at Christmas time that the reason for the season is Jesus … but I doubt that’s what you meant this time.😉

    It has to do with how Earth tilts on its axis as it travels around the sun, whether the North or South Poles are “aimed” at the sun. It’s too early in the morning for me to think in more “traditionally scientific” terms.

  22. Ellen Says:

    During the orbit of the earth around the sun, the earth tilts on its access. Depending on the hemisphere that is pointing towards the sun depends on the season in that area.

  23. Konrad Says:

    “Axial tilt is the reason for the season.”

    It’s not because it puts parts of the Earth closer to the Sun, but because it affects the angle sunlight hits the Earth (when the Earth is closest to the Sun, it is winter in the northern hemisphere).

    Now can someone explain why we call the first day of summer “Midsummer”?

  24. Rob Says:

    umm… the location of the sun in relation to the tilt of the earth?

  25. Kathryn Says:

    The tilt of the earth on it’s axis.

  26. icewolf Says:

    They are caused by the rotation of the Earth combined with its orbit around the Sun, due to its tilt on its axis.

  27. Kathryn Says:

    Now I’m really interested to find out why you’re asking about this. An experiment to see how intelligent your blog followers are? A subplot to a new scifi book you’re working on? Some kind of weird mind-power game in which you will be able to access the atomic structure of those who answer this question and obtain motor control over those who know about the Earth’s axis?

  28. E.A.V. Says:

    The approx. 27 degree tilt of the Earth’s axis as it revolves around the sun and rotates around the axis.

    (That’s from vague memories of elementary science classes, but from recent news, studies of the Haitian Earthquake show that earthquakes change the Earth’s axis tilt by a fractions of a degree and the speed of the Earth’s rotation by several seconds. They have a significant effect on the whole earth, not just localized devastation.)

  29. Janci Says:

    Axis tilt causes the sun to hit us at different angles and therefore different strengths. I hast nothing to do with the distance from the sun, as the distance from the sun is proportionally insignificant. The length of days does contribute, though.

  30. Tine Says:

    The tilting of the Earth as it rotates around the sun.

  31. Robert Says:

    What is axial tilt, Alex?
    Now for double Jeopardy!

  32. Raymund Says:

    The Earth’s axis is not perpendicular to the Earth-Sun plane. In the northern hemisphere winter, the North Pole is pointed away from the Sun and the northern hemisphere gets less sunlight. Reverse in the summer.

    I recently saw on Youtube a video where Harvard students at commencement were asked this question, and many of them gave the wrong answer (distance from the sun).

  33. Andrew Says:

    OK, I’ll bite. My understanding, and this essentially dates back to sixth grade geography, is as follows. The Earth is tilted on its axis at an angle of 23.5 degrees. So let’s picture a line running through the earth from pole to pole. That line. Now we need a second line to create that 23.5 degree angle. That line is the plane, the imaginary disk, if you will, of the Earth’s orbit around the sun. In other words, if you draw an oval(?) representing the orbit around the sun and fill it in, you get a plane. Look at that plane from the side, and you get a line. The earth’s axis forms a 23.5 degree angle with that line. Got it? Good. Now, the earth’s axis will point in different directions throughout the Earth’s revolution around the sun. For about half of the year, the line will point along the line of travel in the orbit. These times are spring and fall. The other half of the year, the axis is oriented so that one end points away from the sun (winter) and the other end points toward the sun (summer) Now, there are only two days each year when the axis is pointing directly away from the sun. Those are the summer and winter solstices. There are also only two days each year when the axis doesn’t point at the sun, or more accurately, toward the interior of the orbital disk, at all. The lines form tangents off of the orbit. Those are the spring and fall equinoxes. So winter is the time when the hemisphere pointing away from the sun gradually starts to point toward the sun. At the halfway point in that process, the axis becomes that tangent. That’s the spring equinox. During the course of the spring, the axis continues to point more and more toward the sun until the summer solstice. Thus begins summer. After the solstice, the axis starts to gradually point away again until the fall equinox and then throught the fall until the summer solstice. Move to the opposite hemisphere, and the timeline is reversed.

    That accounts for the orbital dynamics. The heating and cooling caused by the orientation of the axis account for the weather we associate with each season. And I’m sure solar winds factor in somehow.

  34. Bopper Says:

    Angle of the earth.

  35. Jeanne-Marie Says:

    There was this goddess called Demeter and she had a daughter she loved very much…

  36. Doruk Says:

    Well, I always thought it was because Earth’s axis is tilted and we get summer season when the hemisphere we are on is tilted towards the sun and winter when it is tilted away. I assume this matters because it changes the the entry angle of the light into the atmosphere (and thus the distance it needs to travel). I further assume that the distance within the atmosphere matters more than the distance within space (nothern hemisphere summer happens when earth is at the far end of the eliptical orbit, IIRC) because heat dissipation would be greater within the atmosphere than within the vacuum. I am not entirely sure about this last bit, tough:/

  37. Lionus Says:

    The angle of the Earth in regards to the sun decides the seasons. When the tilt of the earth’s axis “leans” the top of the earth more towards the sun as the planet rotates around the sun we folks up in North America and EurAsia are in our warm summer, while the folks in South America and Australia are having their cooler winter. When the tilt of the earth’s axis places the southern portion of the planet closer (astronomically speaking) to the sun then the seasons are reversed; the north in winter and the south in summer.

  38. Joe the trucker Says:


  39. C.E. Petit Says:

    Seasons result from a combination of several factors. The dominant ones are (1) axial tilt and (2) eccentricity of the planet’s orbit around its star. However, there are also albedo effects (we would have different “seasons” without the reflective polar icecaps, or if cloud cover substantially changed, or…), atmospheric chemistry effects (global warming also changes seasonality, and that’s just the obvious one), and a variety of other geophysical factors.

    Then there’s the whole sun-cycle thingy, too, but that trends more toward “climate” than “seasonality”.

  40. Erin Moore Says:

    The distance of the earth from the sun at different parts of the year.

  41. Ty Says:

    I do.

  42. Cat Says:

    If I remember from science class, the seasons are caused by position in orbit of the earth around the sun, and the tilt of the earth.

    Either that or Chuck Norris kicks the sun when it gets too hot, which causes winter.

  43. Kathy Martin Says:

    Earth’s axial tilt and orbit around the sun.

  44. Gaia or Mother Nature.

  45. Wendy Says:

    Earth’s tilt on its axis as we orbit the sun.

  46. Gillian Says:

    The tilt of the Earth on its axis as it orbits the sun.

  47. Thomas Says:

    The tilt of the earth towards the sun (on it’s axis of course).

    For a little more detail as the earth goes through it’s orbit around the sun one side gets closer to the sun which causes that hemisphere’s summer. On the other side of that orbit the same hemisphere is farther from the sun causing winter for that hemisphere. When both sides are about the same distance from the sun is when you have spring and fall.

  48. Jared Says:

    The seasons are caused by the tilt in the earth’s axis; the degree of the tilt, which is variable, determines the severity of the seasons.

  49. Bradford Says:

    In school they taught us that it is due to the tilt of the earth. I’m glad you asked the question, though, because I always thought that the “tilt” answer seemed a bit mysterious. But with a little reflection, I can see how that would work. To explain it, thought, I need to draw a simple diagram, which I can’t do here. But the key is to consider people living at a particular lattitude, say 45 degrees north. (That’s halfway between the equator and the north pole.) Summer for them occurs when the earth tilts toward the sun, and you can see that at noon, for example, the sun’s rays hit 45 degrees north at a much more direct angle in the Summer than in the Winter. Of course, the same argument works for any particular lattitude in the northern hemisphere.

    The same analysis works for the southern hemisphere, but the Seasons will be reversed. By the way, it occurs to me that a person could use calculus to determine the total amount of solar flux that would impact a particular lattitude. Then he or she could compare the total flux for different lattitudes with the measured average temperature differences for the lattitudes. That would be an interesting project.

  50. SJBell Says:

    I wish I had a pithy, smartass answer…

    Truth is, tilting of the earth’s axis, which causes us to get more or less heat from the sun at different times of the year, which affects the weather in various complex ways.

    But that’s a boring answer, so let’s get philosophical.

    When you think about it, the things that we think of as being identified with the seasons are actually the natural world’s response to the sun and the weather. Flowers bloom in the spring, trees shed their leaves in the autumn, bears hibernate in the winter, etc. So you could say that the seasons are really “caused” by the natural world’s reaction to the cycle of hotter and colder days.

    Going even deeper, you could say that the seasons are actually a human creation, a framework that early farmers imposed upon a much, much, more complicated climactic system so that they understood exactly what was applicable to their work- when to plant crops, when to harvest, what to expect as the year progressed, etc.

  51. n Says:

    The axis of the Earth’s rotation is not perpendicular to the plane of its elliptical orbit around the Sun.

  52. Alan Kellogg Says:

    It’s the angle at which sunlight hits the Earth, the more oblique the angle the more atmosphere the light has to travel through. The more atmosphere the more attenuated the light gets. This is why noon time sun light is stronger than late evening, or early morning, sunlight.

  53. Beccy Higman Says:

    The tilt in the axis about which the earth rotates in relation to the sun, AND the fact that Earth’s orbit around the sun is an elipse. If the axis was at 180 degrees to the sun or if the orbit was circular we would have milder seasons. If both were so we wouldn’t have seasons, but we would stil have a temperature gradient between the equator and poles. I think anyway😉

  54. StevenW Says:

    The tilt of the planets axis in combination with the relative position of the planet in its elliptical orbit to the sun.

  55. Jakk Says:

    The turtle keeps moving around the sun.😉

    Or the tilt of the axis while moving around the sun.

    One of those two.

    Can i have a gold star for mentioning a turtle?

  56. Vickie B Says:

    Earth’s rotation around the sun.

  57. Cathiag Says:

    The tilting of the earth.

  58. Lauren Says:

    The tilt of the Earth’s axis.

    I wonder how many people googled it before commenting?

  59. Berni Says:

    The tilt of the planet. The earth is actually closer to the sun in (Northern hemisphere’s) winter than summer, but the planet is tilted differently, accounting for the temperature difference.

    In another note, I found your _Discord’s Apple_ at my local Safeway. (Of course, I bought it! I’ve read all the Kitty books.)

  60. Ramenth Says:

    Well, you see, there are these oracles. And they have this rod. IF you were to take that Rod and stand up on, oh, say, a stump, and hold it up in the air, the season would change. It’s very useful for getting around; I mean, everything is nice in the Summer, but in the spring sometimes lakes are too big to cross, and in the fall leaves come and fill up bottomless pits so you can get to areas you wouldn;’t be able to reach otherwise. Plus everything freezes during winter, and the rod lets you walk across frozen lakes, even if it does make snow drifts.

  61. Bradford Says:

    Why the Tilt Matters.

    Since I already put my answer above (#49), I thought I’d look to see what some of the other people put. I see that nearly everyone correctly answered that the tilt of the earth is the key, but many folks seem unclear on why the tilt matters. For example, some have said that it affects the distance from the Sun, while others have said that it is due to the additional atmosphere through which the light must travel. Here I believe is why the tilt matters:

    Consider for a moment that you are at a place on the earth where it is noon and the Sun is directly overhead. Consider just the ray of sunlight that illuminates a one meter squared patch of earth. That sunlight is imparting a certain amount of heat and illumination to that one square meter.

    Now instead consider someone in the northern hemisphere at noon on a Winter day. Because of the tilt of the earth, she doesn’t see the Sun as directly overhead, even at noon. Instead, she sees the Sun to the south. Lets consider a similar ray of light that would have illuminated a one meter squared patch of earth had the Sun been directly overhead. Now the ray comes from the south. It strikes the earth at an oblique angle, is stretched out along the surface of the earth in its direction of travel, and now must illuminate and provide heat to a much larger patch of earth. This means that the solar energy per unit area is far less in the Winter. Less heat per unit area means it will be colder in Winter than during the other seasons.

  62. Jean Smith Says:

    Season are due caused by the tilt on the earths axis and the distance from the son.

  63. Doruk Says:

    Bradford: ah, yes, that makes a lot more sense! I think it is more likely than my idea (still not googling it, in order to stick with the rules :P)

  64. Brian S. Says:

    The Earth’s orbit around the Sun along with its tilt(facing away or towards the Sun).

    “Turn, Turn, Turn” by the Byrds comes to mind.🙂

  65. Thomas Says:

    The angle of the Earth in relation to its orbit of the Sun (1 year) which varies the amount of Sun light (heat energy) recieved in any one area of the Earth.

  66. Adam. Says:

    Bradford explained a mechanism noone else touched on above.

    But the effects of axial tilt are more of an “Answer D: All of the above” kind of deal.

    Summer: more photon density at the surface with less atmospheric attenuation over the course of a longer day, leads to more heating of the ground and the ocean at summer latitudes and warm summer weather. All of which are caused by axial tilt rather than the distance to the sun on the eliptical.

    In the winter the opposite applies.

    I suspect that the effect of changes in atmospheric attenuation would be small compared to photon density and day length. But that might be because I’m an RF engineer rather than a climatologist.

  67. Kristian Says:

    The combination of elliptical orbit and Earth’s axis tilt leading to gradual warming and cooling of the earth over the course of a year, as well as the lengthening and shortening of the duration of sunlight in a day.

    The biological response for many species is to adapt growth, activity, dormancy, and reproduction to maximize energy utilization. In a given area, there are tipping points that lead to localized dramatic changes (the seasons shifting).

    Alternatively, they change because the calendar says so (seasons are a abstract construct created by man).

  68. […] 2, 2010 I bet you’re finally wanting to know what was up with my experiment of several days ago, hm?  Well, it was a smashing, roaring success!  Thank you all for the many, many responses!  I […]

  69. Elena. Says:

    The tilt of the axis of the earth.

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