Question about heat in space?

Question

I have a question about the relationship between the distance from our sun and the temperature at that distance.

So we all know that the temperature on Mercury is much higher than on Pluto because it is closer to the Sun. But Earth's distance from the Sun does not remain constant throughout the year, and even though the distance from the Sun changes the temp on Earth seems to stay fairly constant, so what is going on here?

The seasons are not caused by our distance from the Sun changing. The seasons are a result of the Earth's tilt on its axis.

Good answer Crabby......thanks. Yeah I just did the math and our distance from the Sun only varies by 4%. For some reason I was picturing a much more oblong orbit. Thanks again.

Answer 1

winter fall spring summer

Answer 2

Good question--but the answer is complicated, so bear with me. I'm just going to list some of the factors that affect temperatures on earth, but i'll try to do it so you see how they interact:

1) The earth's distance from the sun doesn't vary much (plus/minus maybe 2%).
2) A bigger factor is the Earth's orbital inclination (its axis is tilted in relation to the Sun) That means that in winter, that slant causes the Earth's surface in one hemispher (North or South) to get less sunlight, while the other gets more. When the Earth is on the other side of the Sun, this is reversed. That's why the Southern hemisphere alway s has their seasons reversed from the Northern (i.e. winter in July and summer in January).
3) Thephysics of heating and cooling are such that temperature changes tend to damp out. For example, if you heat something (a pot of water or a planet) it will ratiate off the heat gradually. But the hotter something is in relation to its surroundings, the more efficiently it radiaates off the heat. So large temperature changes tend to be balanced by large rates of heat radiation--making it harder to change the temperature
4) The earth's oceans and atmosphere tend to act as "heat moderators--slowing changes in temperature so they balance out more easily. The way this works is that the atmosphere and water tends to absorb and store heat when the temperature is high--then slowly release it when the temerature falls (at night or in winter). BTW--that's the problem with global warming--the increase of CO2 is causing the atmosphere to retain TOO MUCH heat, throwing the balance off.

Those are the main factors--there are some others as well, less importaant. The bottom line: these factors interact to make the earth's temperature fairly stable. It varies of course--but only within a farily small range.

Answer 3

The distance from the Sun is but one of many factors affecting our temperature.
The Earth's orbit is an ellipse with the absolute distance changing by up to 2 million miles throughout the year; but this is only around 2 % of our distance to the Sun.
The Earth is closest to the Sun in early January and furthest in early July.
The Earth's axial tilt of 23 degrees governs the seasons. We have winter in the northern hemisphere while they have summer in the southern hemisphere and vica versa.
The distance-temperature relationship is governed by the inverse square law.

Answer 4

The temperature of a body in space depends not only on the amount of radiation it receives, but also on its thermal properties. For example, if a body absorbs all energy at visible wavelengths (where the Sun radiates most of its energy) and has a layer which reflects infrared(about 5-11 microns, where most of the energy radiated by heated bodies is) it will have a temperature higher than a truly black body in the same radiation conditions. It also depends on the shape of the body (a spherical body will have a different temperature from a flat one)

As far as Earth is concerned, the energy received by Earth averages about1366 W/m^2, with a high of about 1412 W/m^2 and a low of about 1321 W/m^2 in early July, a variation of about 3.5% from the average. I'll have to do some calculations on the influence of this variation on temperature, I don't have any numbers at hand. but in the case of Earth, there is the thermal inertia which tends to average out these fluctuations.

Note that there are also long term variations in the solar constant, due to various solar cycles; the 11 year cycle was discovered due to its influence in weather, therefore on crops and their prices on the market.

.................................
OK, I finished the calculations, based on black body approximation and spheric, isothermic body. In short, energy received is inverse proportional with squared distance from Sun, while radiated energy is proportional with fourth power of temperature Stefan-Boltzmann law). Therefore, you get
T_max/T_min = Sqrt(D_max/D_min) = Sqrt((1+e)/(1-e)) (the last comes from the elliptical orbit; for Earth, e=0.0167; T is in Kelvin)

If you plug in the numbers, you get a temperature variation of about 4.5-5 degrees C. But this does not take into account thermal inertia (heat can be stored close to Sun and radiated when Earth is far from Sun)

Answer 5

Carbon dioxide levels change. In the winter there is more CO2 and the sun is far away . The CO2 traps the sun's heat rays inside the earth. During the summer we are closer to the sun and also during the summer the is less CO2 in the air because plants' leaves convert CO2 into Oxygen. There is les CO2 so not as many heat rays will be trapped on earth.

Answer 6

The distance doesn't vary much; it's a nearly circular orbit.

The effect isn't enough to be noticeable.

Especially when you consider how far out there Pluto (Former Planet) is.

My, my; a LOT of people don't understand the seasons, do they?