# Will stars on the other side of the galaxy affect gravity here?

• I
• KurtLudwig
In summary, the gravity between two stars is not blocked by intervening mass, but rather decreases with distance. According to General Relativity, gravity is a geometric property of four-dimensional spacetime and is affected by the energy and momentum of matter and radiation. While a distant star may have a negligible effect on our Sun, it still contributes to the overall gravitational field of the galaxy. In fact, all objects in the galaxy, including stars, black holes, and dark matter, have an influence on each other through gravity. Therefore, while the statement that Sagittarius has the main gravitational effect on our Sun is correct, it is not exclusive as other objects also contribute to the overall gravitational field.

#### KurtLudwig

Gold Member
TL;DR Summary
Will the gravity of stars on the other side of Sagittarius not be blocked?
Does intervening mass between two stars decrease the gravitational attraction between these two stars?
Is gravity a local phenomenon in that local mass interacts with the surrounding gravitational field caused by the local star and distant stars?

What have you read about the extent of gravitational effect for a given object? What does General Relativity say that gravity IS ?

I know I'm making it easy, but the simple answer here is "no", gravity doesn't get "blocked", it just decreases with distance. And yes, the galaxy's overall gravitational field is the sum of its parts.

russ_watters said:
I know I'm making it easy

Nothing wrong with that.

If I say that a star on the other side of the galaxy has an almost negligible effect on our Sun. The main gravitational effect is due to Sagittarius. Is this statement correct?

Answering what General Relativity is: General relativity posits that gravity is a geometric property of four-dimensional spacetime. The curvature of spacetime is directly related to the energy and momentum of whatever matter and radiation are present. The relation is specified by a system of partial differential equations. (Which I read about, but which are way above my level.)

KurtLudwig said:
If I say that a star on the other side of the galaxy has an almost negligible effect on our Sun. The main gravitational effect is due to Sagittarius. Is this statement correct?
Yes, but not because anything is "in the way" of its effect, just because it's so far away.

Answering what General Relativity is: General relativity posits that gravity is a geometric property of four-dimensional spacetime.
Exactly, which is why one thing doesn't have any effect on the gravitational impact of another thing, although their effects would be additive and a closer one will have a bigger effect (give similarities in mass).

Looked at another (simplistic) way, you can block EM radiation, but you can't block geometry and gravitational waves are geometry.

Klystron and russ_watters
KurtLudwig said:
If I say that a star on the other side of the galaxy has an almost negligible effect on our Sun. The main gravitational effect is due to Sagittarius. Is this statement correct?
It is correct, in that you say main effect - but notice that it is not exclusive of that distant star. That star still has an influence.

In the grand scheme of things - 'the other side of our galaxy' is pretty much next door, compared to say, the stars of the Andromeda galaxy. They too have an effect on our galaxy (and thereby on our Sun), even though they're 25 times farther away.

And then recall that even whole galaxy clusters affect each other with their gravity. It's all just stars affecting other stars.

256bits
KurtLudwig said:
If I say that a star on the other side of the galaxy has an almost negligible effect on our Sun. The main gravitational effect is due to Sagittarius. Is this statement correct?
There are a hundred billion stars in the Milky Way, plus their satellites, black holes, dark matter, stray gases, etc. So sure, the fraction of that total mass carried by any one star is "negligible". It's possible to calculate exactly how negligible by picking a hypothetical star or a given mass and distance from Earth.

DaveC426913
IOW, negligible - times 100 billion (or even just 10 billion) - is no longer negligible.

It would be an interesting exercise for the OP to work out what the gravitational acceleration would be of some fraction of stars at some set distance from Sol.

For example:
1010 stars at a distance of 105 light years
has the same attraction as
104 stars at a distance of 102 light years.
or
1 star at a distance of 1 light year.

(That can't be right. That means 10% of the galaxy on the far side of the galaxy has more effect (4x more) on Sol than Alpha Centauri!)
Code:
Rationale:

Num.(Sol=1)    Dist (ly)
10^10           10^5
10^8            10^4
10^6            10^3
10^4            10^2
10^2            10^1
10^0            10^0

Last edited:
russ_watters
KurtLudwig said:
If I say that a star on the other side of the galaxy has an almost negligible effect on our Sun. The main gravitational effect is due to Sagittarius. Is this statement correct?
While Sagittarius A has a larger effect than that one star, the combined mass of all the matter closer to the center of the Galaxy than the Sun has an effect on the Sun's orbit many magnitudes greater than Sagittarius A alone does.

alantheastronomer

## 1. How do stars on the other side of the galaxy affect gravity here?

The gravity of stars on the other side of the galaxy does have an effect on the gravity here, but it is very small compared to the gravity of the stars in our own galaxy. The further away a star is, the weaker its gravitational pull will be. Therefore, the stars on the other side of the galaxy have a minimal impact on the gravity here.

## 2. Can stars on the other side of the galaxy cause disruptions in our solar system?

No, the stars on the other side of the galaxy do not have enough influence to cause disruptions in our solar system. The gravitational pull of these stars is too weak to have any significant impact on the orbits of planets in our solar system.

## 3. Are there any instances where the stars on the other side of the galaxy could affect gravity here?

In rare cases, if a star or group of stars on the other side of the galaxy were to undergo a major event such as a supernova explosion, it could potentially have a slight effect on the gravity here. However, this is highly unlikely and would only be temporary.

## 4. How does the distance between stars affect their gravitational pull?

The strength of a star's gravitational pull is directly proportional to its mass and inversely proportional to the square of the distance between the two objects. This means that the further away a star is, the weaker its gravitational pull will be. Therefore, the stars on the other side of the galaxy have a very small effect on the gravity here.

## 5. Is there any evidence of stars on the other side of the galaxy affecting gravity here?

No, there is no evidence to suggest that the stars on the other side of the galaxy have any significant impact on the gravity here. Scientists have extensively studied the effects of gravity and have not found any evidence of it being affected by stars in other galaxies.