The sun would appear much larger and brighter from Mercury than it does from Earth. This is because Mercury is much closer to the sun than Earth is. The sun would take up a much larger portion of the sky, and it would be much more intense. The surface of Mercury would be much hotter, and the sun's rays would be much more damaging.

Here are some specific details about how the sun would look from Mercury:

* Apparent size: The sun would appear about three times larger in diameter from Mercury than it does from Earth. This is because Mercury is about three times closer to the sun than Earth is.

* Brightness: The sun would be about seven times brighter from Mercury than it is from Earth. This is because the intensity of sunlight decreases with the square of the distance from the sun.

* Color: The sun would appear slightly yellower from Mercury than it does from Earth. This is because the Earth's atmosphere scatters blue light, making the sun appear bluer.

* Surface temperature: The surface of Mercury would be much hotter than the surface of Earth. The average surface temperature on Mercury is about 450 degrees Celsius (842 degrees Fahrenheit), while the average surface temperature on Earth is about 15 degrees Celsius (59 degrees Fahrenheit).

Overall, the sun would be a much more dominant feature of the sky on Mercury than it is on Earth. It would be larger, brighter, hotter, and yellower.