How can the parallax method be used to measure the distance of the aurora from the earth?

Question

Websites or explanations here is very welcomed!! thanks a lot!!!!

Answer 1

The parallax method relies on the fact that, if you look at something relatively "nearby" from two different points of view, the thing you're looking at will appear to shift position compared to other things behind it that are far in the background.

For example, try holding your finger out at arm's length, so that some faraway thing (like a building) can be seen behind it. Hold your finger steady, then close one eye. Alternately look at your finger first with your left eye, then with your right. Notice how your finger seems to shift position compared to the building?

If you hold your finger a little closer, the amount of the "shift" increases. If you didn't know how far away your finger was, you could calculate it by knowing how far apart your eyes are, and measuring the amount of the "shift." This would take some trigonometry.

Now, try the same experiment on a larger scale. Instead of your finger, use the aurora. Instead of left eye/right eye, use two different viewing points that are a few miles apart. And instead of a distant building, use the distant stars.

If two people, a few miles apart, both take a picture at the same time of the same aurora, they'll notice something when they compare the photographs. They'll notice that the aurora's position compared to the stars, is "shifted" in one photo compared to the other. By knowing how far apart the observing stations were, and measuring the amount of the shift, they can calculate how far away the aurora is.

Answer 2

RickB is correct. However, you need to be aware that the aurora usually has a very complex shape, different parts are different distances from you, and the shape can change very rapidly. Take two photos at the same instant, from different locations, aiming the cameras at the same star; hold the cameras in the portrait position, rather than landscape. View the left camera's image with your left eye and the right camera's image with your right eye. Then you'll see the aurora in 3D. You can use RickB's method to get the distance for different points by measuring the paralax angle for a star behind each part of the aurora.

Many cameras are useless for this type of photography because they do not have time exposure settings. Because the light of the aurora is very dim, you need a long time exposure, but too long of an exposure will not freeze the aurora if it is moving. With chemical photography, you need fast film and a fast lens like f = 1.4 or better; and you must tell the photolab to "push" the development process. The corner drug story photo department won't know what you mean, so you have to do it yourself or use an expensive professional film developer.

Answer 3

Lay mans answer:

Parallax is just a tiangulaton. Once you get two values of a triangle, You can figure out other values by simple trigonometry.