:INFO
Ice giant around Kepler-51
It is 0.80 times Jupiter's radius, closest in size to Saturn, and 4.0 times Earth's mass, at 0.03 g/cm3, less dense than Earth. A year there lasts 85.31 days, on an orbit 1 times closer to its star than Mercury is to the Sun. Its equilibrium temperature is 439 K, hotter than any desert. The host star Kepler-51 runs at 6018 K with 1.04 times the Sun's mass.

:JOURNEY
Kepler-51 from the inside out
1 0.251 AU
2 0.384 AU
3 0.509 AU

:STATS
[icon:TARGET] Radius | 9.00 Earth radii
[icon:CHART] Mass | 4.0 Earth masses
[icon:FIRE] Equilibrium temperature | 439 K (measured)
[icon:CLOCK] One year | 85.31 days
[icon:BOLT] Orbit radius | 0.3840 AU
[icon:STAR] Host star | Kepler-51 at 6018 K
[icon:USERS] Distance | 2557 light-years
[icon:TRENDING_DOWN] Starlight blocked | 0.769% at each transit

:COUNTER
0.03 g/cm3: less dense than cork

:TIMELINE
🔭🪐📅
2012-01-01 | Kepler-51 b, Kepler-51 c
2014-01-01 | Kepler-51 d

:PATH
What you get from the shadow
The fraction of starlight blocked sets the radius against the star's.

:NOTE
Kepler-51 has 4 known planets. Systems like this are the ones where architecture can be studied instead of guessed at.

:NOTE
Found by Kepler in 2012. Kepler's method needed repetition, not brightness. It could find small planets around faint stars, provided they came round quickly enough to be seen twice.

:NOTE
A transit gives the radius and a separate measurement gives the mass. Having both is what makes a density, and a density is the only clue to composition at this range.

:LINK
https://exoplanetarchive.ipac.caltech.edu/overview/Kepler-51%20c
NASA Exoplanet Archive: the full record for Kepler-51 c