5 New Earth-Size Exoplanets Orbit so Close to Their Star That a Year Takes One Day

Yesterday we found out about the first planet discovered with four suns around it. Today we're back to more conventional systems, with one star and several planets, though this one is far from being "standard" as well. 

Using data from the Kepler space observatory, scientists have discovered that a relatively close star, KOI-500, 1,100 light years away in the constellation Lyra, has five planets orbiting it.

Nothing unusual so far, but these planets, all slightly bigger than Earth, circle the planet incredibly close, they'd all fit comfortably inside Mercury's orbit; the farthest out planet is still 12 tiles closer to its star than the Earth is to the sun.

They circle their parent star in 1, 3.1, 4.6, 7.1 and 9.5 Earth days respectively. The planets are 1.3, 1.4, 1.5, 2.4 and 2.6 heavier than the Earth, the heavier ones are further out.

The interesting part is that the entire thing is stable, five planets packed so close together have significant gravitational effects on each other.

In this case, four of the planets, the outer ones, are in an orbital resonance, which keeps them on their orbits. The four planets return to the same position relative to each other every 191 days.