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Perihelion and Aphelion (2009 July 3)
Posted: Fri Jul 03, 2009 11:08 am
by smita
Today's - July 3, 2009 - APOD
http://apod.nasa.gov/apod/ap090703.html
Does the proximity to sun affect the weather? By how much?
I think in the northeastern US, we are seeing the effect of it
Thanks.
Re: Perihelion and Aphelion
Posted: Fri Jul 03, 2009 1:18 pm
by Chris Peterson
smita wrote:Does the proximity to sun affect the weather? By how much?
Yes, global weather patterns are affected by the Sun's distance. Models used for weather and climate analysis consider as a primary input solar irradiance, which is determined in part by the distance to the Sun. Given the current orbit of Earth, northern summers and southern winters are slightly cooler then they would otherwise be. Our orbit changes, however, so over time the position of aphelion changes as well.
Re: Perihelion and Aphelion
Posted: Fri Jul 03, 2009 1:26 pm
by smita
Thanks for the info.
Re: Perihelion and Aphelion (2009 July 3)
Posted: Fri Jul 03, 2009 6:11 pm
by Phil G
Question:
When the distance sun to earth is listed, is that surface-surface or center-center?
Thanks
Re: Perihelion and Aphelion (2009 July 3)
Posted: Fri Jul 03, 2009 6:21 pm
by The Code
I think its an approximation.. because the actual distance changes...
Mark
Re: Perihelion and Aphelion (2009 July 3)
Posted: Fri Jul 03, 2009 7:10 pm
by bystander
Phil G wrote:When the distance sun to earth is listed, is that surface-surface or center-center?
The distance is large enough that the radius of the respective orbs is insignificant.
Re: Perihelion and Aphelion (2009 July 3)
Posted: Fri Jul 03, 2009 7:23 pm
by BMAONE23
Considering that the difference between perihelion and aphelion is roughly 5m k. The difference between surface distance and center distance (radii differential) is 701,373 k. So as bystander points out, the difference is likely negligible.
Re: Perihelion and Aphelion (2009 July 3)
Posted: Fri Jul 03, 2009 7:51 pm
by Phil G
Thank you all.
You have successfully made me feel much more significant
![Wink ;-)](./images/smilies/icon_wink.gif)
Peace,
Phil
Re: Perihelion and Aphelion (2009 July 3)
Posted: Sat Jul 04, 2009 11:28 am
by DavidLeodis
It is a fascinating comparison. One thing though is causing me confusion.
The perihelion image is dated January 4th and the explanation states it was in 2008. The "on the date of" in the explanation is a link to perihelion and aphelion dates/times (under Universal Time). The periheion for 2008 is stated there to have been on January 3rd at 00 hours (the times will likely be rounded to a nearest hour). I'm probably wrong but doesn't that mean that perihelion was at the start of January 3rd 2008, as 1 hour earlier it would have been January 2nd whereas 1 hour later it would still have been January 3rd.
![Question :?:](./images/smilies/icon_question.gif)