Earth is 4.5 billion years old. K2-33b is 5 to 10 million. In human terms, this planet is a few weeks old. 👶
Meet K2-33b — the youngest fully-formed exoplanet ever detected when NASA's K2 mission and the Keck Observatory confirmed it in 2016 (Nature, 20 June 2016). A super-Neptune a bit larger than Neptune, nearly 500 light-years away in the Upper Scorpius star-forming region in Scorpius.
It races around its young star every 5 days — 20 times closer than Earth is to the Sun — and its star still holds a thin leftover disk of planet-forming material. Nearly every other known exoplanet is a billion years old or more. This one is a live look at how planets are born — including how Earth itself began.
The baby planet.
Sources: Caltech discovery release (20 June 2016); NASA JPL, "NASA's K2 Finds Newborn Exoplanet Around Young Star"; David et al., Nature (2016), "A Neptune-sized transiting planet closely orbiting a 5–10 million-year-old star." Distance note: discovery coverage said ~500 light-years; modern Gaia parallax puts it at ~453 light-years (Upper Scorpius mean ~470 ly).
PROJECTORBIT — the universe, one planet at a time.
