Can You Orbit the Photon Sphere Without Being Pulled into the Event Horizon?

In summary, the conversation discusses the possibility of orbiting the photon sphere without being pulled towards the Event Horizon. It is mentioned that a spaceship cannot move at the speed of light, but it can use thrust to maintain orbit at the photon sphere. The conversation also notes that the details become complicated near the photon radius and that a spaceship can potentially orbit 1mm outside the photon sphere, but caution should be taken due to tidal gravity.
  • #1
avito009
184
4
Am I right when I say that you can orbit the photon sphere and still be not pulled towards the Event Horizon but you need to orbit (In your spaceship) at the speed of light?
 
Astronomy news on Phys.org
  • #2
Your spaceship can't move at the speed of light. Therefore, your spaceship can not free-fall orbit at the photon sphere (whereas photons can). What you can do is use thrust to keep you in orbit at the photon sphere (presumably the thrust is quite strong). The details get pretty hairy around the photon radius though.
 
  • #3
Well, you can stay in orbit 1mm outside the photon spere. If your spaceship has a finite size, some parts can even be inside (think about tidal gravity before you go there!).
 

1. What is the Photon Sphere?

The Photon Sphere is a theoretical region in space where photons (particles of light) can orbit around a black hole. This is possible because the intense gravity of the black hole warps the fabric of space-time, allowing for stable orbits of particles.

2. How is the Photon Sphere different from the Event Horizon?

The Event Horizon is the point of no return for anything that enters a black hole, beyond which escape is impossible. The Photon Sphere, on the other hand, is a region outside of the Event Horizon where photons can orbit. It is not a physical boundary like the Event Horizon.

3. How big is the Photon Sphere?

The size of the Photon Sphere depends on the mass of the black hole. The larger the black hole, the farther out the Photon Sphere will be. For a non-rotating black hole, the radius of the Photon Sphere is about 1.5 times the radius of the Event Horizon. For a supermassive black hole, the radius could be several light years.

4. Can anything besides photons orbit in the Photon Sphere?

In theory, any massless particle could orbit in the Photon Sphere. However, since photons are the only known massless particles, they are the only ones we know of that can orbit a black hole in this way.

5. How does the Photon Sphere affect light passing through it?

The intense gravity of the Photon Sphere causes light passing through it to become distorted and redshifted. This means that the wavelength of the light is stretched out, making it appear redder than it actually is. This effect is known as gravitational lensing and is commonly observed around black holes.

Similar threads

  • Astronomy and Astrophysics
Replies
6
Views
1K
  • Special and General Relativity
Replies
3
Views
499
  • Astronomy and Astrophysics
Replies
6
Views
1K
  • Astronomy and Astrophysics
Replies
15
Views
3K
  • Special and General Relativity
2
Replies
57
Views
978
  • Astronomy and Astrophysics
Replies
11
Views
614
  • Astronomy and Astrophysics
Replies
9
Views
2K
  • Astronomy and Astrophysics
Replies
1
Views
8K
  • Special and General Relativity
Replies
3
Views
841
  • Special and General Relativity
Replies
4
Views
678
Back
Top