Aphelion – July 4th July 3, 2009Posted by baldricman in astronomy.
Tags: aphelion, apsis, earth, july 4th, orbit, perihelion, sun
Tomorrow, July 4th, the Earth will be at it’s furthest point from the Sun, in it’s eliptical orbit. This is known as “Aphelion” (with the closest point known as the Perihelion).
The effect? Well, contrary to what you may think, this does not really effect our seasons in any meaningfull way. The seasons are, of course, created by the tilt of the Earth on it’s axis, in relation to the Sun. However, the Sun will appear slightly smaller in the sky, by roughly 3% (No, you won’t notice that)
This happens once a year, at more or less the same time, and the following table gives the date and time (GMT) of each aphelion. (Table from wikipedia page here)
|2007||January 3||2000||July 7||0000|
|2008||January 3||0000||July 4||0800|
|2009||January 4||1500||July 4||0200|
|2010||January 3||0000||July 6||1100|
|2011||January 3||1900||July 4||1500|
|2012||January 5||0000||July 5||0300|
|2013||January 2||0500||July 5||1500|
|2014||January 4||1200||July 4||0000|
|2015||January 4||0700||July 6||1900|
|2016||January 2||2300||July 4||1600|
|2017||January 4||1400||July 3||2000|
|2018||January 3||0600||July 6||1700|
|2019||January 3||0500||July 4||2200|
|2020||January 5||0800||July 4||1200|
You can see a good representation of the difference in the apparent size of the Sun, in the form of a composite image (from 2 photos, one at Aphelion, one at Perihelion), on the NASA site over here.