[jjeaff]

Iridium has about 85 satellites in service.

SpaceX satellites are much closer and they are planning something around 7,500 of them.

Might not be too hard to look in just the right place with that many floating around.

[Robotbeat]

SpaceX will also be serving orders of magnitude more customers than Iridium. Being closer also means they'll pass in the Earth's shadow earlier in the night than Iridium.