Linear movement with sin() and cos(). Numbers between 0 and PI*2 (TWO_PI which angles roughly 6.28) are put into these functions and numbers between -1 and 1 are returned. These values are then scaled to produce larger movements. 

angle1, angle2 = 0, 0
scalar = 70


def setup():
    size(640, 360)
    noStroke()
    rectMode(CENTER)


def draw():
    global angle1, angle2
    background(0)
    ang1 = radians(angle1)
    ang2 = radians(angle2)
    x1 = width / 2 + (scalar * cos(ang1))
    x2 = width / 2 + (scalar * cos(ang2))

    y1 = height / 2 + (scalar * sin(ang1))
    y2 = height / 2 + (scalar * sin(ang2))

    fill(255)
    rect(width * 0.5, height * 0.5, 140, 140)
    fill(0, 102, 153)
    ellipse(x1, height * 0.5 - 120, scalar, scalar)
    ellipse(x2, height * 0.5 + 120, scalar, scalar)

    fill(255, 204, 0)
    ellipse(width * 0.5 - 120, y1, scalar, scalar)
    ellipse(width * 0.5 + 120, y2, scalar, scalar)
    angle1 += 2
    angle2 += 3