What I have found so far; The star vanishes after 2 hrs 30 mts. I have seen one behind Varrock East bank, one near mining spot near Piscatoris Fishing Colony, and mining spot north of ruins of Uzis. There's another landing spot at Kandarin near mines to south of Ardougne. The discover 'bonus' is 4950 mining xp. If the Star has not yet been discovered the observatory chart gives the landing time and 'not yet discovered'. Wearing a glory improves the chances of gems, I got about 15 gems with glory as against about 1 or 2 without glory. From the one near Uziz i got about 35 k xp, as hardly anyone was there, :-) Also the reward for 200 star dust was 50k coins, 20 noted gold ores, 152 Cosmics and 52 Astrals. As my friend also got the same amount of stuff, it appears that the reward may be same for all. Can someone please confirm.