Hi Everyone!
I’ve been looking at the new pictures (from the Messenger spacecraft) of the planet Mercury.
One thing I’ve wondered about is, from the vantage point of standing on Mercury’s surface, how big would the Sun appear?
What a neat site!
Does this question even have an answer? You can’t look at the sun from Earth unless it is sunrise or sunset, where enough atmosphere is in the way to provide a filter. And Mercury has no atmosphere at all, so you could never look at the sun, except possibly like this -> 
Yes, provided you take a good set of welder’s goggles with you.
Aaah! My eyes!
The goggles… they do nothing!
Q.E.D.'s answer should perhaps be clarified to note that the Sun would cover an angular diameter 2.5 times as wide on Mercury, but would have a surface area 6.6 times as large and be 6.6 times as bright.
Furthermore, Mercury has a noticeably elliptical orbit, so these figures can vary. At perihelion the Sun would be 3.2 times as wide and 10.4 times as big and bright as its average from Earth.
I’m not understanding that simulator. When I put in “Earth” as seen from “Mercury”, I get a ginormous Earth. That’s not right.
You might have the “I want the body to take up 30 percent of the image width” checked. Try messing around with the degrees in the option above it.
Can anyone give some good ideas about an appropriate field of view range to use for the purposes of the OP’s quesion?
Look at the moon, or the sun, from earth, with a field of 5 degrees. Then compare to the sun from mercury, with a field of 5 degrees.
See the “Field of View” section. For some reason it defaults to “I want the body to take up XX percent of the image width”.
That means except for angle & lighting you’d see the same view of the Earth no matter where you viewed it from.