The sun doesn't actually "go down" in the sense of moving downwards. It's the Earth's rotation that makes it *appear* like the sun is setting.

Here's a breakdown of the "speed" of sunset:

* Earth's Rotation: The Earth rotates on its axis once every 24 hours. This rotation causes the sun to appear to rise in the east and set in the west.

* Angular Speed: The Earth rotates approximately 15 degrees per hour (360 degrees / 24 hours). This means the sun appears to move across the sky at a rate of 15 degrees per hour.

* Duration of Sunset: The time it takes for the sun to set is not a fixed time but varies depending on your location and the time of year. It can take anywhere from a few minutes to over an hour.

* Atmospheric Effects: The actual time it takes for the sun to disappear below the horizon is also affected by atmospheric refraction. This bending of light can make the sun appear to be above the horizon even when it's technically below it.

So, to answer your question directly, the sun doesn't have a speed of "going down". It's the Earth's rotation that makes it appear to set, and the time it takes to set depends on several factors.