What is the Angular Extent of Trigonometric Parallax?

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Angular extent refers to the angular size of an object as observed from a specific point, in this case, the semi-major axis of an orbit measured at 7.61". This concept differs from trigonometric parallax, which involves measuring the apparent shift of an object against a distant background from two different positions in Earth's orbit. The discussion highlights the application of parallax to estimate the real size of distant objects based on their angular size observed from Earth. Understanding both concepts is crucial for calculating the linear size of celestial bodies when their distances are known. The clarification of these terms aids in solving problems related to binary stars or orbiting planets.
mahsa
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Hi
I know the meaning of trigonometric parallax, but what is angular extent?
In a problem, it is stated that the true angular extent of semi major axis of the orbit is 7.61".
Is it different from parallax?
Thanks
 
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The angular extent is simply the angular size---i.e. how big it looks.
 
mahsa said:
Hi
I know the meaning of trigonometric parallax, but what is angular extent?
In a problem, it is stated that the true angular extent of semi major axis of the orbit is 7.61".
Is it different from parallax?
Thanks
the typical application of parallax is where the baseline is provided by OUR orbit around the sun.

It sounds to me as if you have a school problem in which there is a binary star or the star has a planet or something orbiting it.

So you are supposed to estimate the real size of a distant object (an orbit) given its angular size seen from earth.

the picture is turned around, the base of the long skinny triangle is out there.

With parallax the baseline is here at home. We get to look at the object from two different locations along the Earth's orbit.

That seems like a difference.
 
Thank you very much! I got it.
so, if I know the distance to that binary or orbit, I know its linear size.
 
mahsa said:
Thank you very much! I got it.
so, if I know the distance to that binary or orbit, I know its linear size.

Yes!
 

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