A slightly improved version of my diagram of our motions in space –
– with the speeds expressed in kilometers per second, instead of per hour.
I think you can actually visualize something leaping half a kilometer (about 500 yards, maybe the length of a street near you?) in a second (the time it takes you to say “thousand-and-one”). That’s how far you are whisked eastward in one second.
Or it would be if you were on the equator. If you’re at latitude 40° north, you’ll whisk along only by 0.36 of a kilometer (about 400 yards) – the cosine of the latitude.
Visualizing something leaping 65 times as far is tougher. That’s how far Earth shifts its whole bulk in that same second.
The point in Cygnus toward which the solar system is heading – nearly 8 times faster again – is near the blue-white supergiant star Deneb, now painted on the surface of the imaginary sphere. Deneb is around 3,000 light-years away and yet is among the 20 brightest stars in our whole sky; we follow far in its wake around the galaxy.
Referndum of ghosts
Russia proposes to stage a referendum in Mariupol, asking the bombed-out city whether it wishes to become part of Russia.
This is as if the United States of America, after obliterating Nagasaki with an atomic bomb, were to ask Nagasaki whether it wishes to become a member of the United States of America.
__________
ILLUSTRATIONS in these posts are made with precision but have to be inserted in another format. You may be able to enlarge them on your monitor. One way: right-click, and choose “View image” or “Open image in new tab”, then enlarge. Or choose “Copy image”, then put it on your desktop, then open it. On an iPad or phone, use the finger gesture that enlarges (spreading with two fingers, or tapping and dragging with three fingers). Other methods have been suggested, such as dragging the image to the desktop and opening it in other ways.
Sometimes I make improvements or corrections to a post after publishing it. If you click on the title, rather than on ‘Read more’, I think you are sure to see the latest version. Or you can click ‘Refresh’ to get the latest version.
This weblog maintains its right to be about astronomy or anything under the sun.
Yes, noticed that flip too. However I have learned perspective empathy from my rather new Southern Hemisphere perch (-34S). Here, everything north is seen from an upside down perspective. Having lived years in the N Hemisphere, this new perspective takes some getting used to. Further, adding the various motions you have illustrated takes some deliberate thought as I gaze outward.
Cygnus/Deneb is visible here this time of the year 2 hours or so before sunrise low in the NW. It is the last part of the Summer Triangle to rise above the northern horizon. The Swan’s northern cross appearance stands upright but on its head. From there the Milky Way rises to the near Zenith where brilliant (and upside down) Scorpio/Sag fill the top of the sky. From there its off to the south and the Southern Cross on its side low to the SW. It’s quite a sight to see the Milky Way span from cross to cross. Now about that motion….😉
“the Milky Way from cross to cross”
Thanks for giving the distance in yards too but when Sir Boris Johnson reintroduces the Imperial system this week it’ll all have to be in such illogical measurements.A strange measurement,a yard,as it, unlike a metre, can’t be used for vertical measurements.You can’t say a building is say 100 yards high.Well people in England vote in Sir Boris Johnson and Sir Jacob Rees Smog so maybe the good people of Nagasaki and Hiroshima would have voted to join the USA!Nowt as strange as folks.
Thanks for the post. It prodded me to review Outrush in Astro Companion in which I learned about the Sun’s movement within the Milky way.
Coincidentally, I was studying the May Telescopic tour to prepare for my visit with my daughter in D.C next weekend to play with her new Celestron telescope that I gave her for Christmas. So I reviewed the “Wide Sky in May” and discovered that the Milky Way galaxy is spinning counter clockwise as viewed from the north. As you wrote, if you walk toward Cygnus in the northeast, you are walking n the direction in which our solar system is revolving around the Galaxy, with the galactic center on your right.
This counter clockwise movement of the Sun in the Milky way is opposite to the Earth’s clockwise movement around the sun (right hand rule), and the moon’s clockwise revolution around the Earth, and the clockwise rotation of the Earth.
By the way, I did learn about the Great Attractor from Wikipedia.
Thanks, Rick. But I think you have “clockwise” and “counterclockwise” (as seen from the north) swapped.
Thank you Guy. I love that diagram! Glad you multiplied the speeds by 3600 to get km/s. I’ve been thinking about these movements since you posted the first diagram. I suppose we could add the motion of the Milky Way toward Andromeda, and the speeding of our local group of galaxies toward the center of the Virgo cluster, et cetera ad infinitum. Two thoughts:
We don’t directly experience any of these cosmic motions. We don’t feel velocity, we only feel acceleration. The spinning Earth doesn’t throw us into space or make it hard to pour a cup of coffee. Our local inertial field is a gravitational version of Plato’s cave. Riding my bicycle down a hill and accelerating from 5 meters per second to 10 meters per second is much more personally consequential than the mind-boggling movements of planets, solar systems, galaxies. Negative acceleration even at very low speeds, e.g. stubbing my toe or dropping an egg on the kitchen floor, is even more noticeable!
We understand the Earth’s rotation, the Earth’s orbit around the Sun, and the solar system’s orbit around the center of the galaxy as closed loops, circular or elliptical. I wonder if the longer movements, e.g. toward the Great Attractor, are also curved, but because the distances are so great we can’t detect the infinitesimal curvature of the tiny fraction of the total curve which we can perceive.
I also wondered about that. Surely the Local Group cannot be falling in a straight line toward the Great Attractor. Is it moving in an ellipse? In that case, is the focus of the ellipse some angular distance, perhaps uncalculable, aside from the Great Attractor? We need help from someone conversant with the theory.