James Brink wrote:When I see star field photos such as this one on June 10 I often see and clearly see here lines and arcs of stars that do not seem random. I have not read about this phenomenon which must relate to star formation. What is known?
The thing to understand about the lines and arc patterns that stars seem to form is that all stars are in motion.
Click to play embedded YouTube video.
Click to play embedded YouTube video.
The video at left is a simulation of the motion of stars inside a massive cluster, and the video at right shows the (idealized) motion of stars in a spiral galaxy.
Click to play embedded YouTube video.
Here is a video showing the motion of two million stars in the Milky Way, as measured by the European sonds Gaia and Hipparcos. Bearing in mind that there are about two hundred
billion stars in the Milky Way, it is a tiny, tiny fraction of the total stellar population of our galaxy that has had its various motions measured by these two space sonds.
The thing to remember is that all stars are in motion, and that the stars themselves are incredibly tiny compared with the vast, vast distances separating them. This adds to the impression that the stars are stationary, because it takes very much longer than a human lifetime for even the fastest-moving stars to appreciably change their apparent positions in the sky.
The stars look "relatively bigger" than they are when we look at them, because the atmosphere of the Earth scatters and spreads their light. Photography often makes stars look bigger, too, due to (among other factors) pixel bleeding. And as human beings we are utterly unable to picture in our minds the incomprehensible distances separating the stars. Also the sky looks pretty much like a canopy to us, where everything appears to be at the same distance from us. Nothing could be further from the truth. Take a look at how the Big Dipper would look if we saw it from other locations than our own:
Click to play embedded YouTube video.
The bottom line is that the lines and arcs that we see in the sky are frozen moments in time, seen from the vantage point of the Earth. The stars themselves, constantly in motion, will destroy the lines and arcs that grace our present-day sky and create other apparent lines and arcs in the sky in the future.
Ann
[quote="James Brink"]When I see star field photos such as this one on June 10 I often see and clearly see here lines and arcs of stars that do not seem random. I have not read about this phenomenon which must relate to star formation. What is known?[/quote]
The thing to understand about the lines and arc patterns that stars seem to form is that all stars are in motion.
[float=left][youtube]https://www.youtube.com/watch?v=VF6J7P2cpn8[/youtube][/float] [float=right][youtube]https://www.youtube.com/watch?v=K5pfXdsrtI4[/youtube][/float]
The video at left is a simulation of the motion of stars inside a massive cluster, and the video at right shows the (idealized) motion of stars in a spiral galaxy.
[youtube]https://www.youtube.com/watch?v=Ag0qsSFJBAk[/youtube]
Here is a video showing the motion of two million stars in the Milky Way, as measured by the European sonds Gaia and Hipparcos. Bearing in mind that there are about two hundred [i]billion[/i] stars in the Milky Way, it is a tiny, tiny fraction of the total stellar population of our galaxy that has had its various motions measured by these two space sonds.
The thing to remember is that all stars are in motion, and that the stars themselves are incredibly tiny compared with the vast, vast distances separating them. This adds to the impression that the stars are stationary, because it takes very much longer than a human lifetime for even the fastest-moving stars to appreciably change their apparent positions in the sky.
The stars look "relatively bigger" than they are when we look at them, because the atmosphere of the Earth scatters and spreads their light. Photography often makes stars look bigger, too, due to (among other factors) pixel bleeding. And as human beings we are utterly unable to picture in our minds the incomprehensible distances separating the stars. Also the sky looks pretty much like a canopy to us, where everything appears to be at the same distance from us. Nothing could be further from the truth. Take a look at how the Big Dipper would look if we saw it from other locations than our own:
[youtube]https://www.youtube.com/watch?v=dFT02IQ18lE[/youtube]
The bottom line is that the lines and arcs that we see in the sky are frozen moments in time, seen from the vantage point of the Earth. The stars themselves, constantly in motion, will destroy the lines and arcs that grace our present-day sky and create other apparent lines and arcs in the sky in the future.
Ann