Not meteors (snowfall) but you can adapt.
App uses 9 Sprites. Hides them all.
SnowStorm.aia (32.9 KB)
Start, then every 15 seconds the app makes another Sprite visible on the Canvas at a random location until all 9 Sprites create a heavy snowfall. Change the image and you have meteorites falling.
Useful information needed to adapt to your requirements.
15 seconds is 7500 ms. The app has 9 sprites, add more until the performance becomes sluggish.
This is what others have recommended as you cannot instantiate Sprites with Blocks. Provide many Sprittes, hide them and display them as required. 