I know that theoretically you can use both statements in English:
a) Look! The sun rises.
b) Look! The sun is rising.
But is anybody (who is a native speaker) saying “Look! The sun rises.”?
In German, for instance, it is absolutely normal (and common) to use the equivalent of statement “a”.
If you wake up early and see the event of ‘the rising of the sun’, you would almost always say
Look! The sun is rising.
Or other expressions such as one of the following:
Look at the sunrise!
Look, the sun is coming up!
This is because the present participle is the tense most often used to refer to what someone or something is doing at the moment of speaking.
As for the present simple
Look, the sun comes up!
Look! The sun rises.
These are not normally going to be used in the context of waking up and telling someone to look at the rising of the sun. For that, you’re almost always going to use the present participle.
The simple present alternatives can be used for that, but such a usage would be uncommon. So, it wouldn’t be wrong to say it, but it would seem strange. A native English speaker would be deliberately departing from normal usage.
The sun rises
The sun comes up
are usually reserved to express habitual events
The sun rises/comes up each day
or to give the time of a single event
The sun rises/comes up tomorrow at 0635.
You could preface this with look to draw attention to this fact, as in
Look! The sun rises/comes up tomorrow at 0635, so we better get up at 0600 so we have plenty of time to see it.
There are additional uses of the present simple, which you can find by searching this site.