- #1
rtd
- 6
- 0
iam in class 11th iam suffering from a great difficulty to understand parallex method , inspite of book's example
High School Parallex Method: Struggling in 11th Class?
Click For Summary
SUMMARY
The discussion focuses on the parallax method, a technique used in astronomy to determine the distance of stars by observing them from two different positions in Earth's orbit. The parallax angle, denoted as Phi (Φ), is critical in this calculation, where the relationship is defined by the equation tan(Φ) = r/d, with 'r' representing the radius of Earth's orbit and 'd' the distance to the star. The participants emphasize the importance of accurately measuring the parallax angle and understanding its relationship to the apparent position of the star. Acknowledgment of the elliptical nature of Earth's orbit is also noted, which affects the precision of the radius used in calculations.
PREREQUISITES- Understanding of basic trigonometry, specifically tangent functions.
- Familiarity with astronomical concepts, particularly parallax and its applications.
- Knowledge of Earth's orbital mechanics and dimensions.
- Ability to interpret diagrams related to parallax measurements.
- Study the derivation and application of the parallax formula in astronomy.
- Learn about the effects of Earth's elliptical orbit on parallax measurements.
- Explore practical examples of parallax calculations using real astronomical data.
- Investigate other distance measurement techniques in astronomy, such as standard candles.
Astronomy students, educators, and anyone interested in understanding distance measurement techniques in astrophysics will benefit from this discussion.
- #2
- 19,378
- 15,605
Explain what you think the parallax (not "parallex") method is and what it does. That is, tell us how you see it and be more explicit about what you aren't following in the explanation in your book.rtd said:
- #3
Tazerfish
- 157
- 39
In the parallax method you look at something(prabably a star) from different positions.
The trick is that an approximately infinitely far away object does not seem to move anywhere.
Even if you change your position.
For example you don't see the sun move in response to your movement.
It stays where it is in the sky, no matter where you are or how you move.
(assuming you don't move somewhere entirely different on the planet)
The thing you are looking at however does move if you change your position.
Just take your finger somewhere in front of your face.
Now move your head without moving the finger.
You will see that the finger seems to change its position relative to the background.
By examining how much its position changes you can determine the distance you are away from it.
http://lcogt.net/files/styles/fourcol-image/public/spacebook/Parallax%20schematic.png
In astronomy the "moving your head" is done by looking at the object from two opposite points on the Earth's orbit.
You might be able to see that the parallax angle does not only appear where it is drawn in but it is also half the difference in apparent position in the object.
So by measuring the angle and because we know the diameter of the Earth's orbit we can determine the distance from the star.
The trick is that an approximately infinitely far away object does not seem to move anywhere.
Even if you change your position.
For example you don't see the sun move in response to your movement.
It stays where it is in the sky, no matter where you are or how you move.
(assuming you don't move somewhere entirely different on the planet)
The thing you are looking at however does move if you change your position.
Just take your finger somewhere in front of your face.
Now move your head without moving the finger.
You will see that the finger seems to change its position relative to the background.
By examining how much its position changes you can determine the distance you are away from it.
http://lcogt.net/files/styles/fourcol-image/public/spacebook/Parallax%20schematic.png
In astronomy the "moving your head" is done by looking at the object from two opposite points on the Earth's orbit.
You might be able to see that the parallax angle does not only appear where it is drawn in but it is also half the difference in apparent position in the object.
So by measuring the angle and because we know the diameter of the Earth's orbit we can determine the distance from the star.
Last edited by a moderator:
- #4
rtd
- 6
- 0
will you please tell me a solved example ?
- #5
Tazerfish
- 157
- 39
Well i have never solved one of these ...
But i am going to give it a try.
## tan(\Phi)=\frac {r}{d} ##
would make sense to me
(it might be wrong)
Phi is the parallax angle drawn in in the picture
r is the radius of the Earth's orbit
d is the distance to the star
solve it and you're done
But i am going to give it a try.
## tan(\Phi)=\frac {r}{d} ##
would make sense to me
(it might be wrong)
Phi is the parallax angle drawn in in the picture
r is the radius of the Earth's orbit
d is the distance to the star
solve it and you're done
- #6
rtd
- 6
- 0
thank u so much
- #7
Tazerfish
- 157
- 39
Remember it might be wrong ...
Especially since the Earth's orbit is elliptical.(that makes the "radius" thing an approximation )
And you'll have to be careful to check whether your parallax angle is the one drawn in or the difference in position of the star.(that is just twice the angle that has been drawn in) Then you use twice the radius or just the diameter of the Earth's orbit
Especially since the Earth's orbit is elliptical.(that makes the "radius" thing an approximation )
And you'll have to be careful to check whether your parallax angle is the one drawn in or the difference in position of the star.(that is just twice the angle that has been drawn in) Then you use twice the radius or just the diameter of the Earth's orbit
- #8
rtd
- 6
- 0
okkk
- #9
Tazerfish
- 157
- 39
ok
The equation seems to be right...
You see the parallax angle is always half the angle between the position of the stars.(that would be the angles drawn in in this one)
so don't worry about that thing with the angle.
The equation seems to be right...
You see the parallax angle is always half the angle between the position of the stars.(that would be the angles drawn in in this one)
so don't worry about that thing with the angle.
Similar threads
Intro Physics
What is the best conceptual high school physics book?
- · Replies 2 ·
- · Replies 18 ·
- · Replies 4 ·
- · Replies 21 ·
- · Replies 1 ·
- · Replies 4 ·
- · Replies 5 ·
- · Replies 18 ·