/-/https/www.sciencebuddies.org/cdn/Files/21464/5/sb-logo.png){kind=logo}
/-/https/www.sciencebuddies.org/cdn/Files/21464/5/sb-logo.png){kind=logo}
Data for the SOHO satellite
-
astronomyguy
Data for the SOHO satellite
I need help for the SOHO satellite cutting-edge project. The grid is shown with North at the very top. That is very confusing to me, since the sun has a 7.25 degree tilt of the axis. I also need to know if the pictures were already tilted so that the poles of the sun are on the top and bottom. If anyone could give me an answer, I'd be gratified. Thanks!
-
astronomyguy
SOHO Data
I'm back. The rotation of sun does not seem to move the sunspots in an up or down motion in the pictures, but I can't be sure. Also, on the grid, the right side says west, and the left says east. Can someone help me soon? I want to be able to finish all of my work in a few days, and finish my science research paper in several days, and then my abstract in a day.
-
hzatz
- Former Expert
- Posts: 15
- Joined: Wed Nov 17, 2004 12:09 pm
More info may be necessary
There isn't quite enough information here for me to be sure I'm answering your question correctly. It'd probably be helpful to include a URL describing the project, or the location you're getting this specific data set from.
I'll assume, however, that you're picking up a time lapse sequence of sunspot activity from some database somewhere. The convention for how to describe the rotation of planets is that they'll match the way we describe the rotation of the Earth. If you can find a globe and spin it for a while, you'll understand this stuff better, although it's possible to just visualize it in your head.
As the Earth rotates, objects on its surface move Eastward. Consider the example of Philadelphia (where I happen to be right now) and San Francisco. The sun rises and sets three hours earlier in Philadelphia than in San Francisco. That means that if you hold up a globe and spin it, Philadelphia will cross the night/day terminators before San Francisco. There's only one way to spin a globe to make that happen, and that's spinning things so that objects move Eastward.
If you hold a globe in front of you, with North at the top, West will be on the right, and East on the left. If a picture is actually labelled in this manner, the odds are that someone has already corrected for the relative tilt of whatever the pictures show. If you don't see any motion up and down, odds are that the pictures have already been rotated. You can confirm this by holding a piece of string or a pencil in front of the computer screen at a seven degree angle and watching the animation. Whatever angle the objects follow will show the rotation of the images.
I'll assume, however, that you're picking up a time lapse sequence of sunspot activity from some database somewhere. The convention for how to describe the rotation of planets is that they'll match the way we describe the rotation of the Earth. If you can find a globe and spin it for a while, you'll understand this stuff better, although it's possible to just visualize it in your head.
As the Earth rotates, objects on its surface move Eastward. Consider the example of Philadelphia (where I happen to be right now) and San Francisco. The sun rises and sets three hours earlier in Philadelphia than in San Francisco. That means that if you hold up a globe and spin it, Philadelphia will cross the night/day terminators before San Francisco. There's only one way to spin a globe to make that happen, and that's spinning things so that objects move Eastward.
If you hold a globe in front of you, with North at the top, West will be on the right, and East on the left. If a picture is actually labelled in this manner, the odds are that someone has already corrected for the relative tilt of whatever the pictures show. If you don't see any motion up and down, odds are that the pictures have already been rotated. You can confirm this by holding a piece of string or a pencil in front of the computer screen at a seven degree angle and watching the animation. Whatever angle the objects follow will show the rotation of the images.
-
Astronomy Guy
- Posts: 3
- Joined: Tue Dec 21, 2004 3:52 pm
I'm back again. I have finished my study of the SOHO images from June of 2004 to December of same year. And the website that I used is
http://sohowww.nascom.nasa.gov/data/synoptic/sunspots/
I originally thought that the relative tilt of the sun has already been corrected in these pictures. HOwever, my data seem to show that many of the sunspots travel slightly to the north in terms of latitude. What does this mean?
Would you be able to help me by entering the address above and see if the SOHO pictures have already been corrected in terms of its relative axis?
Thanks for helping.
Astronomy Guy
http://sohowww.nascom.nasa.gov/data/synoptic/sunspots/
I originally thought that the relative tilt of the sun has already been corrected in these pictures. HOwever, my data seem to show that many of the sunspots travel slightly to the north in terms of latitude. What does this mean?
Would you be able to help me by entering the address above and see if the SOHO pictures have already been corrected in terms of its relative axis?
Thanks for helping.
Astronomy Guy
-
EDS
- Former Expert
- Posts: 67
- Joined: Thu Nov 18, 2004 4:23 am
Hi Astronomy Guy,
After a few minutes of poking around on the site, I couldn't find any coordinates for the images to which you provided a link. That is sort of surprising, actually. They must be somewhere. (The fits file in that directory is just a flat field image for making corrections to the data, with no useful info.)
My guess is that the photos are oriented in a way that is fixed with respect to either the solar axis of rotation or the plane of the earth's orbit, but which convention they've used and which direction is "up" is unclear. (There are also some other possible conventions, but they're likely to be similar enough to one of the other two to make no difference over a timescale of months.)
If you dig around some, you may be able to find an answer. But, that may not even be necessary.
Another way to look at this experiment is to turn it on it's head and ask, "What can you tell about the rotation axis of the sun *from* the photos themselves?"
After all, if you were the first person to take photos like these, there'd be no way to know how they were oriented with respect to the sun's rotation except by looking at what the sunspots do over time. (Assuming you didn't have a telescope and spectrograph handy to measure it in other ways.)
If you're crafty, you should be able to answer your own question as a part of the analysis.
Good luck!
- Erik
After a few minutes of poking around on the site, I couldn't find any coordinates for the images to which you provided a link. That is sort of surprising, actually. They must be somewhere. (The fits file in that directory is just a flat field image for making corrections to the data, with no useful info.)
My guess is that the photos are oriented in a way that is fixed with respect to either the solar axis of rotation or the plane of the earth's orbit, but which convention they've used and which direction is "up" is unclear. (There are also some other possible conventions, but they're likely to be similar enough to one of the other two to make no difference over a timescale of months.)
If you dig around some, you may be able to find an answer. But, that may not even be necessary.
Another way to look at this experiment is to turn it on it's head and ask, "What can you tell about the rotation axis of the sun *from* the photos themselves?"
After all, if you were the first person to take photos like these, there'd be no way to know how they were oriented with respect to the sun's rotation except by looking at what the sunspots do over time. (Assuming you didn't have a telescope and spectrograph handy to measure it in other ways.)
If you're crafty, you should be able to answer your own question as a part of the analysis.
Good luck!
- Erik