47 votes
Accepted

Does the sun cross other spiral arms in its movement around the galaxy's center?

What is a spiral arm? The reason that the Sun, in principle (but see below), may cross spiral arms is that galactic spiral arms are not rigid entities consisting of some particular stars; rather they ...
pela's user avatar
  • 38.3k
20 votes
Accepted

Which star / galaxy is moving away from us the fastest?

When a galaxy recedes from us, the light we see from it is redshifted. For galaxies at cosmological distances, this redshift is fundamentally different from a Doppler shift; whereas the latter is due ...
pela's user avatar
  • 38.3k
7 votes

Motion of rogue planets

On the numbers Rogue planets are thought to be more abundant than stars in the milky-way and depending on where you make the cut-off, rogue dwarf-planets for example, are expected to enormously ...
userLTK's user avatar
  • 24k
6 votes

Movement of stars over long periods of time

It is called precession. The rate of change is about 1 degree every 72 years. Since the pyramids were built about 4500 years ago, the Earth's pole has precessed about 62 degrees since then. The ...
Greg Miller's user avatar
  • 5,867
5 votes
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Is our Solar System moving independently through our galaxy?

The arms of a spiral galaxy are "gravity waves" Stars orbiting the galaxy are pulled towards them and speed up as they approach, and then are slowed down as they leave. So an arm of the ...
James K's user avatar
  • 122k
5 votes
Accepted

Inverse of the sunrise equation - finding locations with a given sunrise time on a given day

To avoid the headaches associated with finding roughly two dozen similar solutions in the zig-zagging time zone boundaries , you might want to stick with UTC. If you want to deal with local time - it'...
uhoh's user avatar
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5 votes

Does the sun have a vertical movment?

Does the sun have a vertical movment? Sure it does! People who follow solar system bodies with the highest accuracy, including NASA's JPL, use the solar system barycenter (center of mass) for the ...
uhoh's user avatar
  • 30.8k
5 votes

How do galaxies move in space?

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 ...
pela's user avatar
  • 38.3k
4 votes

Which star / galaxy is moving away from us the fastest?

From what I know I don't think they have categorized that this specific galaxy, for example, is the fastest one moving away from the Milky Way Galaxy. There are two reasons for this: First of all, ...
Gaurav Mall's user avatar
4 votes
Accepted

In 31.5kyr, Epsilon Eridani and Luyten 726-8 will be < 1ly close; but how distant from the Solar system?

These stars are currently moving away from us, in the case of Epsilon Eridani, at 15.5 km/s. In 31500 years they will be further away than they are now, the distance can be calculated by applying ...
James K's user avatar
  • 122k
3 votes

Why does mass naturally move closer toward's the center of other masses?

Think at the surface of a ball. A straight line within this curved surface is a great circle. Take some point on the ball. Draw two great circles (apparent straight lines in the surface) starting in ...
Gerald's user avatar
  • 11.6k
3 votes

Inverse of the sunrise equation - finding locations with a given sunrise time on a given day

As @Andy says, at any time there is a great circle around the Earth where the Sun is currently at the horizon, either rising or setting (or both at two points in the (ant)arctics). This great circle ...
AstroFloyd's user avatar
  • 1,044
3 votes

Inverse of the sunrise equation - finding locations with a given sunrise time on a given day

Due to the complexity of the problem (see my comment above) and the fact that you only want a rough answer why not try calculating the times of Sun rise / set at say one degree intervals for the whole ...
James Screech's user avatar
3 votes

How Does Earth Move In Relation To The Stars

If north is up, right ascension should increase left to right on the near side of the celestial sphere. The near side of the Earth should rotate left to right with a period of 23h56m04s. The prime ...
Mike G's user avatar
  • 18.7k
3 votes

How Does Earth Move In Relation To The Stars

The orientation of Earth wrt the stars repeats each sidereal day (thus ~23:56h). The visible night sky only changes each (synodic 24h) day due to the different direction the sun is at when considering ...
planetmaker's user avatar
  • 19.4k
2 votes
Accepted

What would happen if you jumped out of a moving spacecraft?

If the spacecraft is not accelerating, the astronaut leaves the airlock and just floats outside, not moving relative to it. If the rocket is accelerating they "fall" down towards the stern from the ...
Anders Sandberg's user avatar
2 votes

Does the sun cross other spiral arms in its movement around the galaxy's center?

On the other hand the found materials (minerals / isotopes ) show clear evidence that the sun did NOT cross those spiral arms. Spiral arms as areas with higher star density pose the threat of super ...
eagle275's user avatar
  • 311
2 votes

It moved in a straight line with sparkling track.What could it be?

It is most likely a jet contrail. Not all contrails are persistent, and a high altitude jet can be seen over a great distance. A fireball may leave a trail, but if it does, then it is likely to ...
James K's user avatar
  • 122k
2 votes

How are galaxies moving so much and why are they moving?

There are several sources of movement for galaxies. Galaxies may rotate. Galaxies are formed essentially from matter collapsing under gravity into "clumps". This process isn't uniform due to ...
Jonathan Twite's user avatar
1 vote
Accepted

Our Solar System’s interstellar movement in relation to the Alpha Centauri System

If you were looking down on the galaxy from above with 12 o'clock pointing from the Sun to the Galactic center, then using SIMBAD we can get the galactic co-ordinates as approx (315,-0.6) in longitude,...
astrosnapper's user avatar
  • 8,357
1 vote

Why aren't planetary bodies static?

It's simply because the sun and planets were formed out of a big pile of dust. Originally the dust was spinning. So once the dust became planets, it kept spinning around. That's all there is to it -...
Fattie's user avatar
  • 1,126
1 vote

Why does mass naturally move closer toward's the center of other masses?

The short answer is that the Einstein field equation relates the energy, momentum, and stress of matter to curvature in such a way so that it would be true. We could certainly imagine other ...
Stan Liou's user avatar
  • 7,904
1 vote

Are there good animations of the movement of proximate stars over long time periods?

you may want to try RECONS http://www.recons.org/ they have an animation of 10 year movement of Proxima Cen. http://www.recons.org/proxima.movie.large.gif
william's user avatar
  • 19
1 vote

What exactly is 'eastward movement'

Eastward movement mentioned in the book that you're reading means that if you view the earth revolving around the sun from a vantage point in the solar system and if you kept the north pole upwards in ...
Aniansh's user avatar
  • 111
1 vote

Motion of rogue planets

Relative to Earth, based on the movement of the Solar System through space, and the rotation of the Milky Way itself, 60 km/s or above is probably a good cutoff. While it's probably nearer 45 km/s, ...
Victor's user avatar
  • 111

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