<p>I have been reading the <a href="http://omniweb.gsfc.nasa.gov/html/ow_data.html" rel="nofollow noreferrer">OMNIWeb data documentation</a> in order to clarify one particular question without success. I need to associate each measurement in the OMNI dataset to a moment in time at the sun (at least to narrow it to a time interval). Therefore, I need to understand how long it takes for the solar wind to get from the sun to the point where it is measured. I understand that the solar wind velocity is variable, so this time interval is constantly changing.</p>

<p>Could you please help me understand this question? Can the solar wind measurements be used to trace back into the moment at which it left the sun? I would be very grateful if you could explain or point me to some sufficient references.</p>

CC BY-SA 3.0
2017-02-07T10:50:42.030Z
That's going to be tough, there isn't a single, fixed speed that all components of solar wind travel. You might consider asking a more basic question first, for example "How are variations in solar wind near Earth correlated to events on the Sun?" and slightly adjust your text to explain what you are doing. Because lots of people work very hard to try to "understand how long it takes for the solar wind to get from the sun to the point where it is measured" and it's a full time job.
uhoh
CC BY-SA 3.0
2017-02-07T10:56:21.627Z
Thanks. When you talk of components of solar wind travelling at different speed you mean the different types of particles that compose the solar wind?
Geno Whirl
CC BY-SA 3.0
2017-02-07T11:02:58.593Z
The wind (air) on Earth is high density, the atoms are constantly bumping together, so it all sort-of moves at the same speed, like a crowded highway. The solar wind in space is really sparse, and atoms, ions, electrons are spending most of their time moving in nearly straight lines (this is not exactly true) like a highway with very few cars, so every particle could be moving at a different speed. Really you should read more about what the solar wind is really like to begin with, and I shouldn't try to explain things in comments. Just this once though. :)
uhoh
CC BY-SA 3.0
2017-02-07T12:11:12.443Z
Could you give me some references to the state of the art in the "understanding of how long it takes for the solar wind to get from the sun to the point where it is measured", please?
Geno Whirl
CC BY-SA 3.0
2017-02-07T12:44:23.277Z
I'm sorry this isn't how stackexchange works. [Take the tour](http://astronomy.stackexchange.com/tour) first and then take a look at some other questions and answers. Here are [the ones tagged with](http://astronomy.stackexchange.com/questions/tagged/solar-wind) `solar-wind`.
uhoh
CC BY-SA 4.0
2021-11-24T15:47:11.420Z
See the following article:  https://www.aanda.org/articles/aa/full_html/2018/03/aa31831-17/aa31831-17.html
honeste_vivere
<the-sun><data-analysis><resource-request><solar-wind>
Tracing back OMNI data to the sun
Geno Whirl
# Tracing back OMNI data to the sun

(Asked by: username_0 on 2017-02-07)

I have been reading the [OMNIWeb data documentation](http://omniweb.gsfc.nasa.gov/html/ow_data.html) in order to clarify one particular question without success. I need to associate each measurement in the OMNI dataset to a moment in time at the sun (at least to narrow it to a time interval). Therefore, I need to understand how long it takes for the solar wind to get from the sun to the point where it is measured. I understand that the solar wind velocity is variable, so this time interval is constantly changing.

Could you please help me understand this question? Can the solar wind measurements be used to trace back into the moment at which it left the sun? I would be very grateful if you could explain or point me to some sufficient references.

**Tags:** the-sun, data-analysis, resource-request, solar-wind

> **Comments:**
> **username_1**: That's going to be tough, there isn't a single, fixed speed that all components of solar wind travel. You might consider asking a more basic question first, for example "How are variations in solar wind near Earth correlated to events on the Sun?" and slightly adjust your text to explain what you are doing. Because lots of people work very hard to try to "understand how long it takes for the solar wind to get from the sun to the point where it is measured" and it's a full time job.  
> **username_0**: Thanks. When you talk of components of solar wind travelling at different speed you mean the different types of particles that compose the solar wind?  
> **username_1**: The wind (air) on Earth is high density, the atoms are constantly bumping together, so it all sort-of moves at the same speed, like a crowded highway. The solar wind in space is really sparse, and atoms, ions, electrons are spending most of their time moving in nearly straight lines (this is not exactly true) like a highway with very few cars, so every particle could be moving at a different speed. Really you should read more about what the solar wind is really like to begin with, and I shouldn't try to explain things in comments. Just this once though. :)  
> **username_0**: Could you give me some references to the state of the art in the "understanding of how long it takes for the solar wind to get from the sun to the point where it is measured", please?  
> **username_1**: I'm sorry this isn't how stackexchange works. [Take the tour](http://astronomy.stackexchange.com/tour) first and then take a look at some other questions and answers. Here are [the ones tagged with](http://astronomy.stackexchange.com/questions/tagged/solar-wind) `solar-wind`.  
> **username_2**: See the following article:  https://www.aanda.org/articles/aa/full_html/2018/03/aa31831-17/aa31831-17.html  

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