What will happen if the earth's axis remains parallel to itself all around the orbit?

Answer 1

If the equatorial plane were perpendicular to the orbital plane, there would be dramatic seasons. At the solstices, everything on the side of the equator facing the sun would receive 24 hours of daylight, and the other side would have 24 hours of night. At the equinoxes, the entire earth would have 12 hours of day and 12 hours of night.

I think you may have meant to ask about what would happen if the equatorial plane were PARALLEL to the orbital plane. If this were the case, there would be no seasons. Every point on Earth (other than the poles) would have 12 hours of day and 12 hours of night at all times. The poles would experience permanent twilight. If the equatorial plane were perpendicular to the orbital plane, there would be dramatic seasons. At the solstices, everything on the side of the equator facing the sun would receive 24 hours of daylight, and the other side would have 24 hours of night. At the equinoxes, the entire earth would have 12 hours of day and 12 hours of night.

I think you may have meant to ask about what would happen if the equatorial plane were PARALLEL to the orbital plane. If this were the case, there would be no seasons. Every point on Earth (other than the poles) would have 12 hours of day and 12 hours of night at all times. The poles would experience permanent twilight.

Answer 2

If Earths axis of rotation were perpendicular to the plane of its orbit the seasons on Earth would not vary (much). Most plants in temperate zones would have evolved differently (no need to conserve nutrients and energy during a non-existant "cold winter season".
It would be one continuous season. The tilt of our planet gives us seasons. no tilt means no season change.

Answer 3

If the Earth's equator were parallel to it's orbit the Earth would no longer be tilted on it's axis, thus eradicating our seasons. We would have one continuous season.

Answer 4

nothing