# How is the ecliptic and galatic disk of the Milkyway oriented to each other?

Relevance

The answer is that they are inclined by 60.2 degrees. Here's how you get this:

The celestial coordinates of the pole of the ecliptic are

(alpha1, delta1) = (18 hours, 90-23.4393 degrees)

= (270 degrees, 66.6 degrees)

The number 23.4393 is the inclination of the earth's axis to the ecliptic (also called "the obliquity of the ecliptic").

According the the Observer's Handbook, the celestial coordinates of the north pole of the Milky Way are

(alpha2, delta2) = (12 h 51 m, 27 deg 8 min)

=(192.8 degrees, 27.1 degrees)

To calculate the inclination between the ecliptic and the Milky Way disk (i.e., the galactic plane), we need to calculate the distance between the ecliptic pole and galactic pole. This is done with the following spherical-trigonometry formula for the angle between two points on a sphere:

angle = arccos (sin (delta1) * sin (delta2) + cos (delta1) * cos (delta2) * cos (alpha1-alpha2))

If you plug in the above numbers, you get

angle = 60.2 degrees

This is the inclination between the ecliptic and the galactic plane.

• Jim6 years agoReport

This is one of the best answers I've ever seen!

• Login to reply the answers
• Dr. Bob has the right answer: the ecliptic is inclined at an angle of 60.19 - 62.6 degrees relative to the galactic plane.

• Login to reply the answers
• The galactic equator is highly inclined to the ecliptic. Something along about 70 degrees.

• Login to reply the answers
• I agree with the above answer. Highly inclined. It looks like about 70 or 80 degrees if you just glance at a star chart.

• Login to reply the answers
• Login to reply the answers
• Login to reply the answers