Not really. 66k is pretty darn fast, though I can appreciate that on a large enough circle (the presumed orbit around the sun over the course of a year) that may not cause an extreme acceleration (though still a measurable one, which strangely cannot be and is not measured...)

• I don't think it would cause acceleration since we are not going faster are we?

There isn’t any “mass” outside of equation. That’s why scales measure weight instead! There is no “mass” to measure (nor gravitation which also cannot be measured). It is NOT a coincidence that when you combine the mathematical contrivances of mass and gravitation, they return to the real (and measured) weight they began (and were measured) as!

• Mass is pretty simple, how heavy is something relative to its size. In science its synonymous with density.
• Mass and weight seem the same but they are not. Mass is a measure of the density of an object, while weight is a measure of the effect of gravity on that mass. For example, even on the earth since the mass of the earth is not uniform, I can have an object that weighs one weight and move it to another area of the earth and it will weigh another weight. The density or mass did not change, but its weight has.

I don’t! I’m saying that we don’t do those things, and that is literally “astronomical fiction”. If we did, we could measure such motion (through interferometry for one)! Because we can’t (and haven’t), it is most reasonable and scientific (emperical) to conclude that there is no such motion. That is what michelson-morely actually established :(. Astronomy is barely science at all - it’s merely a pastime for rich dilettantes. That’s why it has produced virtually nothing of scientific value in millennia!

• 1725 when James Bradley discovered stellar aberration. This is (apparent) yearly change in positions of all stars in the sky due to Earth's own motion. Aberration arises due to adding up of the speed of light coming from the star and Earth's own speed. This is a very complex phenomenon and its description requires some math.
• Another, much simpler, consequence of Earth's motion is stellar parallax wich was first found in 1838. If Earth changes its position relative to the stars, then the stars should appear to change position in the course of the year. Not just positions like circling the earth. But thier positions are relative to each other!
• A third discovery demonstrating Earth's motion was that of Doppler effect.

• These are all motions relative to other objects in space.
• According to the theory of relativity, we can always move to a reference frame in which the Earth is not moving--i.e., its "inertial" reference frame. So it is technically possible to define a reference frame in which the Earth does not move, while the Sun, planets, and stars orbit around the Earth, but making this reference frame consistent with our observations of Doppler shift and parallaxes would be very complicated. It is much simpler to explain our observations in a reference frame where the Earth does move, and Occam's razor directs us, to use the simplest explanation whenever possible.