what is a parallax?

Answer 1

parallax from an astronomical point of view can be a difficult concept to grasp. try holding your finger at arms length then closing one eye and then switching eyes, you will notice that the due to the slightly different locations of your two eyes your finger will apear to be in two different positions compared to the background (computer screen).
Another interesting way to see it is when you are riding (for your saftey) in a car focus on an object to the side. you will notice objects nearer you than that point will be moving quickly in the opposite direction than you. objects behind your focus point will actually appear to be moving in the opposite direction!
on another topic: it is this discrepency in our vision which is a major player in our ability to see 3D.

Answer 2

1. The change in the position of an object in the heavens due to the orbit of the earth. Observable parallax in the fixed stars is a proof of the rotation of the earth around the sun.

2.With a lens-shutter camera, parallax is the difference between what the viewfinder sees and what the camera records, especially at close distances. This is caused by the separation between the viewfinder and the picture-taking lens. There is no parallax with single-lens-reflex cameras because when you look through the viewfinder, you are viewing the subject through the picture-taking lens.

3.An optical illusion which occurs in analog meters and causes reading errors. It occurs when the viewing eye is not in the same plane, perpendicular to the meter face, as the indicating needle.

4.The apparent motion of a relatively close object with respect to a more distant background as the location of the observer changes.

5.The perceived movement of a distant object such as a moon, planet, or star due to the movement of the Earth.

These are fancy-word definitions, but i can put it in my words:

Place a finger about 20cm from you. If you focus on the background, your finger will appear to split. If you focus on your finger, the background will appear to split (though not very obvious).

Answer 3

It is the apparent shift in position of an object when you view it from different directions. As mentioned above, you can demonstrate it easily by holding up one finger at arm's length in a direction where there are no objects closer than 10 feet or so and closing one eye. Now switch eyes. Your finger will seem to jump to one side against the background of things 10 feet away. The closer your finger is to your face the farther it will appear to jump. That is parallax. We can see a smaller shift in the position of nearby stars against the background of more distant stars by taking a picture once every 6 months. One picture at one part of Earth's year long orbit and the other picture 6 months later from the point in Earth's orbit on the opposite side of the Sun, 186 million miles away.

Answer 4

Parallax is a shift in view caused by distance.

It is most noticed in cameras with viewfinders. The viewfinder doesn't see exactly what the taking lens sees at all distances because of the small distance between the two lenses.

Answer 5

Parallax refers to the small angle between two nearly parallel lines. If you observe a nearby star against the background from opposite sides of the earth's orbit, it will appear to shift slightly, and the amount of shift can give its distance. With a bit of trig, you can determine that a shift of one second of arc, given that the diameter of the earth's orbit is 186 million miles, corresponds to a distance of about 20 trillion miles, or 3.26 light years. This distance is (not surprisingly) called a parsec.

Answer 6

When you take a reading from an instrument that uses a pointer in front of a graduated scale you must position your eye exactly above the pointer, otherwise you will introduce an angle that will give a less tan precise reading.

Answer 7

As the Earth moves in its orbit, the apparent positions of the stars seem to change. The measurement of this is in arcseconds, and called paralax.

Answer 8

what IS a parallax?