I know I learned this in school and it all made sense back then, but somehow I've forgotten the logic behind it, and so if you guys could fill me in, that would help a lot.

Why is it cold in June/July in Australia but hot in Dec/Jan? To my understanding, the heat of Earth is generated by the Sun, and around Dec/Jan, Earth is at its furthest away from the Sun (so shouldn't it be cold regardless of where you are located on Earth?), and for June/July, Earth is closest to the Sun yet it's quite cool (temperatures of 8 degrees C)...

Of course it has something to do with the Northern and Southern Hemispheres, and the tilt of the Earth, but what is that something? I always understood that the tilt of Earth only affected how much sunlight we get at certain times of the year, but I guess it does more.

Sure, I could check wikipedia or Google, but I'm not ashamed of not knowing something, and so if anyone else doesn't quite know the physics behind this, then it's not just me that it is helping.

Tilt of the earth's axis determines the concentration of sunlight/heat, right? Like the difference in intensity shining a flashlight directly at a piece of paper vs. how it becomes diffused if shined at an angle. During a hemisphere's summer the hemisphere is tilted toward the sun, during winter it's tilted away.

As I understand it that has a more significant effect than the change in the earth's distance from the sun at a certain point over the course of its elliptical orbit because the change in distance is negligible as a ratio of the overall distance between the two.

Ok, so what effect does the distance from the Sun have on Earth?

The sun is actually closer to the northern hemisphere in the winter.

From http://www.letstalkscience.ca/hands-on- ... e-sun.html :

The reason for the difference in temperature between the summer and the winter actually has to do with the tilt of the Earth’s axis. If the Earth were not tilted at an angle, there would be no summer or winter.

In the summer, the northern hemisphere is tilted toward the Sun which means that the Sun’s rays hit this part of the Earth’s surface more directly. Since there is more direct sunlight, more of the Sun’s energy is absorbed by the land surface and as a result the temperature is higher. Depending on where you live in relation to the equator, if you look up towards the Sun at noon (12 p.m.) in the summer, you will see that the Sun is close to being overhead.

In the winter, the northern hemisphere is tilted away from the Sun which means that the Sun’s rays hit this part of the Earth in a more oblique or slanted manner. Since there is less direct sunshine, less energy is absorbed by the surface and the temperature is lower. If you look up towards the Sun at noon in the winter, you will see that the Sun lower in the sky.

The southern hemisphere experiences the reverse of the northern hemisphere. When it is summer in the northern hemisphere, it is winter in the southern hemisphere and vice versa.

So remember, seasons are all about the tilt of the Earth’s axis, and not the distance between the Earth and the Sun!

Fantastic answer. Thanks both Groucho and Jiffy.

So, is there no effect on the Earth and the distance between the Sun at different times of the year? Does Earth orbit the Sun in a perfect circle or is it elliptical and therefore is closer at certain times?

It's elliptical. Earth's average distance from the sun is 150 million km, but in January it's at its closest distance (147 million km) and in July it's at its furthest (152 million km).

So, do you know of any difference to the Earth's temperature or conditions from when it is 147km away compared to when it is 152km away? Does that explain why Northern Hemisphere summers are generally hotter than Southern Hemisphere summers..?

Well it's furthest away during summer in the Northern Hemisphere and closest during summer in the Southern Hemisphere. Not sure if there is a noticeable effect on temperature from the change in distance.

I'm going to search for this. Thanks