If the Sun was moving , wouldn't the shape not be round ?

[Ralien]

Hiya , I am new here  and have been considering shapes . Recently I considered the Suns shape and its apparent roundness . I then considered movement of the Sun and thought to myself if it was moving then how can it retain being a round shape . My question to you all is, If the Sun was moving , wouldn't the shape not be round ? 

[swansont]

Straight-line motion at constant speed has no effect - it’s exactly the same as if the object is at rest and everything else is moving.

Accelerations are another matter. The sun rotates, so it’ deforms as a result. It bulges a bit at the equator, making it an oblate spheroid rather than a sphere.

 

[Ralien]

5 minutes ago, swansont said:

Straight-line motion at constant speed has no effect - it’s exactly the same as if the object is at rest and everything else is moving.

Accelerations are another matter. The sun rotates, so it’ deforms as a result. It bulges a bit at the equator, making it an oblate spheroid rather than a sphere.

 

Ok , but what about at night when we see stars that are in patterns such as big dippers , these paterns are constant and have been forever . Wouldn't these patterns change if stars were moving about ? 

[swansont]

1 minute ago, Ralien said:

Ok , but what about at night when we see stars that are in patterns such as big dippers , these paterns are constant and have been forever . Wouldn't these patterns change if stars were moving about ? 

They do change, but since stars are far away, their relative location doesn’t move much in a human lifetime, or even several lifetimes. The closest ones generally change faster, since the angular motion depends on distance, same as things on the horizon looking like they move slower than things up close.

https://www.skyatnightmagazine.com/advice/constellations-move-change-over-time

[Janus]

3 minutes ago, Ralien said:

Ok , but what about at night when we see stars that are in patterns such as big dippers , these paterns are constant and have been forever . Wouldn't these patterns change if stars were moving about ? 

Let's give an example of how the distance between stars and their relative speeds work. Alpha Centauri is the closest star to our own, at 4.3 ly. this is equal to 4e13 km. Our Sun orbits the galaxy a ~230 km/sec.  That's 7e9 km per year.  If this were the relative speed between Alpha Centauri and ourselves, then after 100 yrs, Alpha C would have shifted just 1 degree in position.  But we don't move that fast relative to Alpha C.  Alpha C, along with all the other stars in our local neck of the galaxy, orbits the galaxy along with us.  They are not like the scenery we drive past on the road, but like other cars on the road keeping more or less the same pace as us.  So the relative speeds between the stars is much smaller than that 230 km/sec, and their apparent movement in the sky that much less noticeable.

[Ralien]

11 minutes ago, Janus said:

Let's give an example of how the distance between stars and their relative speeds work. Alpha Centauri is the closest star to our own, at 4.3 ly. this is equal to 4e13 km. Our Sun orbits the galaxy a ~230 km/sec.  That's 7e9 km per year.  If this were the relative speed between Alpha Centauri and ourselves, then after 100 yrs, Alpha C would have shifted just 1 degree in position.  But we don't move that fast relative to Alpha C.  Alpha C, along with all the other stars in our local neck of the galaxy, orbits the galaxy along with us.  They are not like the scenery we drive past on the road, but like other cars on the road keeping more or less the same pace as us.  So the relative speeds between the stars is much smaller than that 230 km/sec, and their apparent movement in the sky that much less noticeable.

Your answer seems very assertive and positive but can you please answer , how we got from not been able to tell which body was moving to knowing which body was moving ? 

[John Cuthber]

56 minutes ago, Ralien said:

Your answer seems very assertive and positive but can you please answer , how we got from not been able to tell which body was moving to knowing which body was moving ? 

We can tell the earth is rotating.
https://en.wikipedia.org/wiki/Foucault_pendulum

[Ralien]

11 minutes ago, John Cuthber said:

We can tell the earth is rotating.
https://en.wikipedia.org/wiki/Foucault_pendulum

Great and I agree the Earth is rotating and it also tilts and moves compared to the Sun . However , this does not necessary mean the Sun is moving unless somebody has devised a method to show the Sun is moving ? 

I am at my post limit now as a new member so will not be able to further reply until tomorrow unfortunately . 

 

[swansont]

2 hours ago, Ralien said:

Your answer seems very assertive and positive but can you please answer , how we got from not been able to tell which body was moving to knowing which body was moving ? 

Orbits are accelerations, and you can tell you are accelerating. But the speed was given relative to the galaxy center.

 

[studiot]

Just now, Ralien said:

Great and I agree the Earth is rotating and it also tilts and moves compared to the Sun . However , this does not necessary mean the Sun is moving unless somebody has devised a method to show the Sun is moving ? 

I am at my post limit now as a new member so will not be able to further reply until tomorrow unfortunately . 

 

well done for spotting the first day post limit.

Most new members don't.

 

As regards your question,

The Sun and stars are balls of firey gas. In fact they are in what we now recognise as the fourth state of matter ie plasma, which is similar to a gas but hotter.
Anyway it is a fluid.

I wondered if you were thinking that balls of fluid should change shape when they are translating (moving along) like they do on Earth ?

They certainly change shape because of the resistance to movement provided by whatever they are moving in.

for instance raindrops become pear shaped as they fall through the air resistance.

 

However in space there is no resisting medium to cause this.

[Phi for All]

1 hour ago, Ralien said:

I am at my post limit now as a new member so will not be able to further reply until tomorrow unfortunately . 

I think you get 5 on your first day. It's an anti-spam measure.