Much less terrifying than a 5-Earth-mass planet. Such a planet would be quite easy for a spacecraft to crash into. But if all that mass is the size of a tennis

Much less terrifying than a 5-Earth-mass planet. Such a planet would be quite easy for a spacecraft to crash into. But if all that mass is the size of a tennis ball, it would be very easy to miss. Unless your aim was perfect you'd just slingshot around it.