Stellar parallax | Stars, black holes and galaxies | Cosmology & Astronomy | Khan Academy

Another version of the stellar parallax introduction. Created by Sal Khan.

Cosmology & Astronomy on Khan Academy: The Earth is huge, but it is tiny compared to the Sun (which is super huge). But the Sun is tiny compared to the solar system which is tiny compared to the distance to the next star. Oh, did we mention that there are over 100 billion stars in our galaxy (which is about 100,000 light years in diameter) which is one of hundreds of billions of galaxies in just the observable universe (which might be infinite for all we know). Don't feel small. We find it liberating. Your everyday human stresses are nothing compared to this enormity that we are a part of. Enjoy the fact that we get to be part of this vastness!

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[khanacademy]

@onecrazysim there are many ways to do it. I did it this way since I found it easier to visualize.

[shantidevi]

I'm just 13 years old but this is so easy that anyone can learn it

[seanbrownsociety]

Great mathematic explanation. Exactly what I was looking for. 👌

[RubberOnRock]

The angle measurement is often measured relative to distant stars/galaxies, for example if you are looking at a "near" star you would measure its parallax angle relative to that of a "very far" star which you would approximate to have a zero parallax change as the Earth orbits due to the distance between Earth and the far star being much greater than that of Earth and the near star.

Useless fact: The astronomical distance "parsec" is the distance (x) at which the parallax is 1 arc-second.

[___jd]

Your videos are really cool and educational. As a visual learner I really learn a lot from the style of your vids. :)

[Clipster]

This is basically how range finders work, correct? I know that you can calculate a distant object by looking at it from two points (knowing their distance apart) where one is to be the "right angle" of the triangle and the other is to be your measured angle 90 - theta where theta would be how far over you have to look from changing your position. Of course you are going to get more accuracy the further those two points are with respect to the distant object.

[Dorlando]

Hi. First, congratulations to khanacademy for all the videos in YT =).
I have problems with the audio... is very soft (at least, in this video). Thanks!

[alexblake]

How do we know how far away the sun is? If our solar system is ripping through space at over 600, 000 miles/hr and the other celestial bodies are also moving then the ranges would be changing.

[baneoflife]

What exact instruments are used to detect theta??

[dlu]

I think that Sal should represent the distance "d" as 1 AU to make the trig a bit easier.


At 7:22.

[pon]

Sal..is it one of your plans to make videos on foreign languages?such as Spanish?

[chissstardestroyer]

Mr. Khan, isn't Parallax basically the original inspiration for trigonometry, pray tell?

[cosmosgato]

It amazing what you can with ingenuity.

[crorens]

@fosheimdet "theta" greek letter often used to name an angle (like alpha beta etc.)

[DanMunteanu]

Do you really need both measurements of the same Theta angle? And then does it allways take six months to calculate the parallax for a star? Besides it sounds like you need to be very precise about the time you take your measurements to have that 90' with the Sun.

[mikeuu]

Very nice, unfortunately, it has been discovered that the Earth only moves a short distance 14036K a year. So in 6 months we would only move 7018K. as per the TYCHOS MODEL of the solar system. a new modle based on an additional movement just uncovered, or discovered, by Simon Shack. Thus bringing the stars 42366 TIMES CLOSER than your process.
You do an excellent job explaining it.

[chissstardestroyer]

For you are basically trying to triangulate your position based on landmarks, or the position of other things at that, Mr. Khan; that is how I guessed that it would be, but I want to know what you think. Surely the principle seems very similar to triangulation regarding Parallax.

[MichaelKhaimraj]

@mignik01 um, no i don't actually. but honestly, i don't think anyone cares. lets not start an argument, let learn about Steller Parallax!

[mignik]

@DiabolicProductions2 agreed. was just having some fun.

[BlueAsYourEyes]

When he said 'to the west' at 5:36 did he mean to the east?