First say thanks to this,Shuairan. It runs really well in my N900(which is bought today!). Actually this app is one big reason for me to buy a N900.
I just wonder whether the picture you attached in the first page is the real screenshot from N900. Coz I just found the Stellarium on mine doesn't has the colour of the sky, I mean the red colour of the dusk. And I've already enable the Atmosphere.