private void placeAsteroids () {
		//if initial large asteroid speed is 3, for round 2 is 4, and round 3 and 4 it is 5
		int speed = 3;
		if (asteroids < 134)
			speed = 4;
		if (asteroids < 99)
			speed = 5;
		
		Participant a = new Asteroid(0, 2, EDGE_OFFSET, EDGE_OFFSET);
		a.setVelocity(speed, random.nextDouble()*2*Math.PI);
		a.setRotation(2*Math.PI * random.nextDouble());
		screen.addParticipant(a);
		
		a = new Asteroid(1, 2, SIZE-EDGE_OFFSET, EDGE_OFFSET);
		a.setVelocity(speed, random.nextDouble()*2*Math.PI);
		a.setRotation(2*Math.PI * random.nextDouble());
		screen.addParticipant(a);
		
		a = new Asteroid(2, 2, EDGE_OFFSET, SIZE-EDGE_OFFSET);
		a.setVelocity(speed, random.nextDouble()*2*Math.PI);
		a.setRotation(2*Math.PI * random.nextDouble());
		screen.addParticipant(a);
		
		a = new Asteroid(3, 2, SIZE-EDGE_OFFSET, SIZE-EDGE_OFFSET);
		a.setVelocity(speed, random.nextDouble()*2*Math.PI);
		a.setRotation(2*Math.PI * random.nextDouble());
		screen.addParticipant(a);
		
		//if round 2 or above creates an additional asteroid in the bottom center
		if (asteroids < 134) {
			a = new Asteroid(3, 2, SIZE/2, SIZE-EDGE_OFFSET);
			a.setVelocity(speed, random.nextDouble()*2*Math.PI);
			a.setRotation(2*Math.PI * random.nextDouble());
			screen.addParticipant(a);
		}
		//if round 3 or above creates additional asteroid in the top center
		if (asteroids < 99) {
			a = new Asteroid(0, 2, SIZE/2, EDGE_OFFSET);
			a.setVelocity(speed, random.nextDouble()*2*Math.PI);
			a.setRotation(2*Math.PI * random.nextDouble());
			screen.addParticipant(a);
		}
		//if round 4 creates two additional asteroids on either side of the ship
		if (asteroids < 57) {
			a = new Asteroid(1, 2, EDGE_OFFSET, SIZE/2);
			a.setVelocity(speed, random.nextDouble()*2*Math.PI);
			a.setRotation(2*Math.PI * random.nextDouble());
			screen.addParticipant(a);
			
			a = new Asteroid(2, 2, SIZE - EDGE_OFFSET, SIZE/2);
			a.setVelocity(speed, random.nextDouble()*2*Math.PI);
			a.setRotation(2*Math.PI * random.nextDouble());
			screen.addParticipant(a);
		}
		
	}