How is the plane of our solar system oriented compared to the plane of our galaxy?

Question

In other words, does the diameter of our solar system lie parallel to the diameter of the Milky Way galaxy, like two dinner plates lying on a table? Or, are we closer to perpindicular, as if one of the dinner plates were standing on end?

ANOTHER THOUGHT -- I just realized that we should be able to make an educated guess. The elliptic is path planets make across our sky. Since all planets are (approximately) in the same plane, the elliptic should represent the plane of our solar system viewed from earth. Likewise, the Milky Way should represent the plane of our galaxy viewed from Earth, with its center towards Saggitarius. Maybe we could estimate it by the angle between the elliptic and the Milky Way.

Answer 1

They are not parallel and your approach (of comparing our plane and the galactic plane) is a good one.

In the equatorial system (the one using declination and right ascension to mark positions in the sky), the North ecliptic pole is located at R.A. = 18h 00 m (= 270 degrees) and DEC = 66.5607 N (in degrees and decimal fractions). The ecliptic is the great circle located everywhere at 90 degrees from the ecliptic pole.

The closest galactic pole is located at RA=12h51m (192.75 degrees) and DEC=27.1333 N. It is called the North Galactic pole but it is really a "south" pole (based on the direction of the disk rotation around the centre of the Galaxy).

The distance separating both poles, on the sphere, is the angle made by the two planes (ecliptic and galactic).

The angle I get is 60.2276 degrees (60 deg. 14 min.).

The angle made where the two plane cross, on the celestial sphere, is also 60.2276; the maximum distance between the two planes is also 60.2276 (the beauty of spherical trigonometry).

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The direction towards which the solar system appears to be moving (called the Solar Apex) is R.A. 18h04 min (=271 degrees) DEC = 30 degrees. If the Sun were on a perfect orbit along the Galactic disk, you'd expect this apex to be exactly 90 degrees from the galactic pole (i.e., exactly along the galactic plane).

The distance between the apex and the Galactic pole is 67.36 degrees, meaning that the Sun is not going exactly along the Galactic plane; it is making an angle of a little over 22 degrees with the Galactic plane.

The Apex is making an angle of almost 37 degrees with the ecliptic pole, meaning that the Sun's vector makes an angle of over 53 degrees with the plane of the ecliptic.

(In spherical trig., the words "distance" and "angle" are somewhat synonym)


R.A. are to the celestial sphere what the longitudes are for Earth; R.A. are measured in units called "hours" (15 degrees per hour) and there are 24 hours in a complete circle (360 degrees).

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Cos(distance) = Sin(DEC_1)*Sin(DEC_2) + Cos(DEC_1)*Cos(DEC_2)*Cos(diff. in R.A.)

On Earth (taking it as a sphere):
Cos(distance) = Sin(LAT_1)*Sin(LAT_2) + Cos(LAT_1)*Cos(LAT_2)*Cos(diff. in Long.)
The distance is in degrees and minutes; one minute = 1 nautical mile (by definition) = 1.1515 statute mile = 1.851851 km

Answer 2

Sky Atlas 2000.0 shows the ecliptic crossing the galactic equator at an angle of about 60°. You can get a direct impression of this on a night when both the Milky Way and several planets are visible, as the planets will roughly outline the ecliptic for you.

Answer 3

i believe its parallel, but i could be wrong, i do know that we are in the orion arm, which is the middle of three arms of our spiral galaxy, so we're somewhere in the middle of the edge of our galaxy and the black hole thats at the center of it