PUR

Mercury
A probe orbiting Mercury.
NaviComp name	PUR
NaviComp coordinates	X: -400 Y: -890
Has atmosphere	No
Has solid surface	Yes
Can be landed on	Yes
Can be splashed-down on	No

Overview

PUR (or Mercury) is the second closest planet to SOL, and one of two planets that have SOL within NaviComp range.

It is a small, solid planet with no atmosphere. It can be landed on, but only with extreme care due to its powerful gravitational pull. 

PUR is the approximate half-way point between HOM and SOL. 

From PUR (+7) you can reach STA (950), HOM (930), SOL (950) and BLU (870).

Trivia

• The small size and high gravitational pull (a little over 1 NCU/s) is due to its high density.
• It may be used as a checkpoint to SOL in Mission 12, or to BLU in Mission 28. Despite that, it is never officially required to accomplish a task on PUR in any Career mission. This makes PUR one of the three planets not officially visited on Career Mode, along with GOL and ENC.

• A geometric positioning experiment performed using the NaviComps of multiple spacecraft indicates that PUR's calculated diameter is 6 Units, and not a radius of 1.5 NaviComp units as initially reported. (Photos in the comments section below)
• It is possibly an analogue for Mercury, much like RED is an analogue of Mars and YEL is an analogue of Saturn, due to its proximity to SOL. There is also a planet in Kerbal Space Program named Eve that is similar to PUR and is in fact, KSP's version of Venus.