Syntax: proximity [speed | velocity | projectiles | ships] [<distance>]
Proximity Radars give you a direct distance from you to all other objects in
your current starsystem, including planets, ships, and stars.
The optional speed/velocity mode lists all of the objects, with their speed
instead of their distance. For tactical situations and the like.
Proximity projectiles will list all projectiles aimed at your ship.
Proximity ships will list only planets and ships in the system.
All proximity modes support an optional distance argument which limits the
entries shown to only those within that distance of your ship.