Is the equator the only meridian that is a great circle?

Answer 1

The equator is a great circle. Meridians of longitude that cross over the north and south poles are also great circles. For every location on a great circle, it's antipodal location is also on the circle. Other than the equator itself, any great circle crosses the equator at two antipodal locations, 180° apart. Other than the equator and meridians of longitude that run due north and south, any great circle reaches it's maximum latitudes at two locations that are 90° of longitude east and west of the two locations where the great circle crosses the equator.
Yes, since the intersecting plane that hypothetically forms the equator would cut through the center of the sphere.

Answer 2

All meridians of longitude are semi-great-circles. Each one spans between the north

and south poles, and the other half of the great circle marks a different longitude.

The equator and all other parallels of latitude are circles, but only the equator is

a 'great' one.

Answer 3

No, it only runs from the north pole to the south pole. the circle it would have formed if it run all the way round the Earth becomes the 180 degree meridian (or international date line) on the other side of the planet.

To understand this you need to move your 'imaginary' point of observation to be above the north pole. From this viewpoint the Earth would look like a circle with the pole in the middle and the meridians divide the circle up in 10 degree sections (like two protractors held back to back). There are of cause 36 of these sections in the circle and opposite the 0/360 degree point you find the 180 degree point. Thus a point on one side is always 180 degrees apart from its opposite.

Answer 4

Yes, exactly. Every meridian of longitude is a semi-circle that joins the poles.

The Prime Meridian, in combination with the 180-degree meridian, form a complete 'great' circle.

Answer 5

No. Circles don't have ends, but The Prime Meridian does.

It begins and ends at the earth's poles, and passes through Greenwich.

So the Prime Meridian ... and every other meridian of longitude ... is 1/2 of a great circle.

Answer 6

No, besides the equator, any meridian (a line of longitude) can also be considered a great circle. A great circle is defined as the largest circle that can be drawn on a sphere, and any meridian fulfills this criteria.

Answer 7

The equator is slightly longer due to the earth being a little flattened at the poles.

Answer 8

The equator is a parallel of latitude, not a meridian.

Yes, it's the only parallel that's a great circle.