So in the Milky Way galaxy there is a massive black hole in the middle and everything is rotating around it including our planetary system. Since the time we have invented telescopes and charted the skies has anyone charted our movement around the black hole. How far have we moved since records began.
A restatement of the question would be: “what do we know about the orbit of the sun around the galactic center?” We do have an approximate idea of the orbital period (around 225 to 250 million years) and consequently its speed relative to the galactic center, around 230 km/s (828,000 km/h).
The most recent measurement of our orbit is that the Sun is 25,800 ly from the center with an orbital speed of 227 km/sec. That article doesn’t say what the length of the Galactic Year would be based on that distance and velocity. I thought I saw someone compute it, but can’t find it now.
One thing that most people don’t appreciate is that the Sun’s orbit is not a simple Keplerian ellipse. Orbits are ellipses when the two bodies are small and compact enough to approximate them as point bodies. The Sun is that compact, but the Milky Way is not. In other words, we don’t just orbit the black hole, but also all the other stuff: stars, nebulae, etc.
So the Sun’s orbit is something like the way horses on merry-go-rounds travel, going up and down with respect to the galactic plane, while also going around. If you “unrolled” it, it would resemble a sine wave. It takes roughly 80 million years to do one up-and-down cycle, so it does about three of them every galactic year. Right now it’s moving towards the north of the galactic plane.
Incidentally, we have only about 16 years left before the Great Apocalypse – 16 galactic years, that is. We’re only going to make about 16 more revolutions around the galactic center before the approaching collision with the Andromeda galaxy gets close enough that tidal forces between the two galaxies will begin to permanently alter just about all of the large-scale orbital dynamics in both galaxies!
So, we’ve done about 20 laps, right? Is that the most direct answer to the OP?
Using round numbers, yes, just under 20 laps around the center of the galaxy since the formation of earth and the solar system as we know it. The last time we were “here” in our orbit, the first dinosaurs had not yet quite evolved.
You may also be interested to know that we’ve also tracked other stars orbiting the central black hole. For ones closer to it, the orbits are much more dramatic.
How do we know we have done close to 20 laps? If each lap is a few hundred million years. And we have been looking through telescopes for about just a few hundred years.
We know how long one orbit takes. We know how long the Sun and Earth have existed as the entities we know and love.
Divide one time interval by the other.
That would give a bogus result if there was a reason to think any of this motion has changed materially since the Galaxy formed and the Sun & Earth coalesced out of it. But we have no reason to think that. So simple division suffices.
The first applications of the telescope for astronomy were in 1609 by Galileo, Harriot, and probably others in 1609. That was 411 years ago. If a galactic year is 250 million years and the sun’s orbit around the galactic center is circular, then the sun has traveled 0.00059 degrees of arc since then.
By way of comparison, suppose you want circumnavigate the earth. You can start by walking 65 meters ( 0.00059 degrees relative to the center of the earth). That’s roughly the distance across Times Square in New York. It takes the earth less than a minute to travel 0.00059 degrees around the sun and it takes about 4 seconds for the moon to travel 0.00059 degrees around the earth.
Yeah, I’ve wondered what it’s like being on a planet orbiting S62, which gets up to 10% of the speed of light at closest approach to A*.