Can you see galaxies move

Will we see our sister galaxy tumbling while coming toward us, i. Galaxies move though space independently of the orientation of their axis of rotation. That this is true can be appreciated from the fact that their direction through space is relative ; that is, in the reference frame of an observer that is passing the galaxy in its plane, it is moving like a frisbee, whereas in the reference frame of an observer who is moving along its axis of rotation, it is moving like an American football:.

Galaxies form by accreting gas which often lies in filaments of gas, and this is thought to have a tendency to align their spins with the filaments. Higher-mass galaxies grow by mergers along filaments, which should align their spins perpendicular to the filament.

I'm unsure if it has actually been confirmed observationally, but it is seen in simulations e. Krolewski et al. Thus, a merger between a massive and a low-mass galaxy will have a tendency to make them meet with their spins at right angles of each other. But this alignment is only in a broad, statistical sense, and mergers at all angles do indeed occur. Sign up to join this community. The best answers are voted up and rise to the top.

Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Learn more. How do galaxies move in space? Ask Question. Asked 1 year, 9 months ago. Active 1 year, 9 months ago. Viewed times. Improve this question. Add a comment. Active Oldest Votes. That this is true can be appreciated from the fact that their direction through space is relative ; that is, in the reference frame of an observer that is passing the galaxy in its plane, it is moving like a frisbee, whereas in the reference frame of an observer who is moving along its axis of rotation, it is moving like an American football: Galaxies form by accreting gas which often lies in filaments of gas, and this is thought to have a tendency to align their spins with the filaments.

Improve this answer. What'd we see? The movements would be chaotic, right? Also, your sketch displays a drill-like motion of a spiral. In actuality, wouldn't that motion very rare?

How about galaxies moving like a coin being tossed? They do indeed keep their orientation, due to conservation of angular momentum except when they collide. But astronomers have been studying their position for thousands of years. Tracking the position and movements of the stars is known as astrometry. We trace the history of astrometry back to BC, when the ancient Greek astronomer Hipparchus first created a catalog of the brightest stars in the sky and their position.

His student Ptolemy followed up with his own observations of the night sky, creating his important document: the Almagest. In the Almagest, Ptolemy laid out his theory for an Earth-centric Universe, with the Moon, Sun, planets and stars in concentric crystal spheres that rotated around the planet. He was wrong about the Universe, of course, but his charts and tables were incredibly accurate, measuring the brightness and location of more than 1, stars.

A thousand years later, the Arabic astronomer Abd al-Rahman al-Sufi completed an even more detailed measurement of the sky using an astrolabe. One of the most famous astronomers in history was the Danish Tycho Brahe. He was renowned for his ability to measure the position of stars, and built incredibly precise instruments for the time to do the job. He measured the positions of stars to within 15 to 35 arcseconds of accuracy.

Just for comparison, a human hair, held 10 meters away is an arcsecond wide. He lost his in a duel, but had a brass replacement made. In , Friedrich Bessel was the first astronomer to measure the distance to a nearby star 61 Cygni.

He used the technique of parallax, by measuring the angle to the star when the Earth was on one side of the Sun, and then measuring it again 6 months later when the Earth was on the other side. Over the course of this period, this relatively closer star moves slightly back and forth against the more distant background of the galaxy. And over the next two centuries, other astronomers further refined this technique, getting better and better at figuring out the distance and motions of stars.

But to really track the positions and motions of stars, we needed to go to space. In , the European Space Agency launched their Hipparcos mission, named after the Greek astronomer we talked about earlier. Its job was to measure the position and motion of the nearby stars in the Milky Way. Over the course of its mission, Hipparcos accurately measured , stars, and provided rough calculations for another 2 million stars.

That was useful, and astronomers have relied on it ever since, but something better has arrived, and its name is Gaia. The spacecraft will track the motion of million stars, telling us where everything is going over time.

It will be a mind bending accomplishment. Hipparchus would be proud. With the most precise measurements, taken year after year, the motions of the stars can indeed be calculated. The familiar stars in the Big Dipper, for example, look how they do today. But if you go forward or backward in time , the positions of the stars look very different, and eventually completely unrecognizable. The speed a star moves is typically about 0. This is almost imperceptible, but over the course of years, for example, a typical star would have moved across the sky by about half a degree, or the width of the Moon in the sky.

In that same year period, it would have moved 5. Very fast. When a star is moving toward or away from us, astronomers call that radial velocity. They measure this by calculating the doppler shift. The light from stars moving towards us is shifted towards the blue side of the spectrum, while stars moving away from us are red-shifted. Between the proper motion and redshift, you can get a precise calculation for the exact path a star is moving in the sky.

We know, for example, that the dwarf star Hipparcos is moving rapidly towards us. The motions of the stars is fairly gentle, jostling through gravitational interactions as they orbit around the center of the Milky Way. But there are other, more catastrophic events that can make stars move much more quickly through space.