# Earths elliptical orbit

• 10-24-2016, 11:49 PM
Flashowl
Earths elliptical orbit
I am trying to create visual representation of the earths orbit on my sons bedroom wall. However some details of the ellipse and it position in relation to the sun are eluding me so I wonder if someone here could help.

I have a few questions...
1. If you were to draw an imaginary line between the furthest points of the ellipse (x axis) would the position of the sun fall somewhere on this line?
2. Do the periapsis and the apoapsis occur at the two ends of this x axis? (I'm assuming yes if Q1 is yes)
3. What is the width of the widest part of the ellipse in km (length of the y axis) and does this intersect the centre of the sun at 90 degrees to the x axis?

Apologies if this doesn't make any sense or if I have used the wrong terminology, I'm kinda new to this.
• 10-25-2016, 12:47 AM
KathyNS
Re: Earths elliptical orbit
Welcome to the forum.

1. Yes. The line is called the major axis of the ellipse.
2. Yes.
3. You should look up the eccentricity of the Earth's orbit to determine the length of the minor axis relative to the major axis. The Sun does not lie on the minor axis. It is at one of the two foci of the ellipse.
• 10-25-2016, 12:54 AM
smeyer8015
Re: Earths elliptical orbit
https://en.wikipedia.org/wiki/Earth%27s_orbit

You're looking at about a 3% difference in minor axis to major axis. so on an 8x8 wall the difference would be about 3 inches. Barely perceptible.

Scott
• 10-25-2016, 03:42 AM
jaetea
Re: Earths elliptical orbit
As Scott said, if you draw it correctly on an 8'X8' wall I highly doubt you will be able to tell it is NOT a perfect circle. That is how slight the eccentricity is.

Here is a graphic to illustrate, they are drawn correctly to scale (from Astronomy Magazine):

http://www.astronomyforum.net/attach...hmentid=144295

Cheers,
JT
• 10-25-2016, 08:46 AM
Flashowl
Re: Earths elliptical orbit
Hi everyone. Thank you so much for your quick responses. I can see now that the ellipse is exaggerated on most pics I've seen previously. To be honest I am a little relieved because drawing a circle is going to be a lot easier!