Parallax (1 Viewer)

Yindi

Member
Is there a difference between annual, stellar and trigonometric parallax.

Which one is 2p and which one is p. Some places say that they are all p, while other sources say trigonometric parallax is half of the annual parralax.

thank you.

someth1ng

Retired Nov '14
I believe they're all the same.

Use half the angle (p).

kiinto

Member
Parallax is the apparent shift of an object relative to a more distant background, due to an observers motion.

Annual parallax is the apparent shift of an object relative to a more distant background, due to the earths motion around the sun (i.e. using the diameter of the earths orbit as the baseline, 2AU).

Stellar Parallax is when this idea of parallax is applied to a star.

Trigonometric parallax is a method by which a stellar parallax is used to define the distance to a star (or distant object). It is done by first finding the annual parallax and then dividing it by two (i.e. the parallax of an object with a baseline of 1AU). This can then be plugged into the d=1/p formula.

As far as I know that's how it breaks down.

someth1ng

Retired Nov '14
kiinto is right. It's a bit more specific but you don't really need to know stellar parallax (afaik).

Yindi

Member
Parallax is the apparent shift of an object relative to a more distant background, due to an observers motion.

Annual parallax is the apparent shift of an object relative to a more distant background, due to the earths motion around the sun (i.e. using the diameter of the earths orbit as the baseline, 2AU).

Stellar Parallax is when this idea of parallax is applied to a star.

Trigonometric parallax is a method by which a stellar parallax is used to define the distance to a star (or distant object). It is done by first finding the annual parallax and then dividing it by two (i.e. the parallax of an object with a baseline of 1AU). This can then be plugged into the d=1/p formula.

As far as I know that's how it breaks down.
Yes, that's what I thought, but never have I seen a source, other than HSC online, define Trigonometric parallax as half the annual parallax. Most text books, and solutions to past papers just plug annual or trigonometric parralax into the formula.