     NASA's Hubble Space Telescope precisely measured the
mass of the oldest known planet in our Milky Way galaxy. At an
estimated age of 13 billion years, the planet is more than twice as
old as Earth’s 4.5 billion years. It’s about as old as a planet can
be. It formed around a young, sun-like star barely 1 billion years
after our universe’s birth in the Big Bang. The ancient planet has
had a remarkable history because it resides in an unlikely, rough
neighborhood. It orbits a peculiar pair of burned-out stars in the
crowded core of a cluster of more than 100,000 stars. The new Hubble
findings close a decade of speculation and debate about the identity
of this ancient world. Until Hubble’s measurement, astronomers had
debated the identity of this object. Was it a planet or a brown
dwarf? Hubble’s analysis shows that the object is 2.5 times the mass
of Jupiter, confirming that it is a planet. Its very existence
provides tantalizing evidence that the first planets formed rapidly,
within a billion years of the Big Bang, leading astronomers to
conclude that planets may be very abundant in our galaxy.
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Credit: NASA, Brad Hansen (UCLA), Harvey
Richer (UBC), Steinn Sigurdsson (Penn State), Ingrid Stairs (UBC),
and Stephen Thorsett (UCSC). |
Oldest Known Planet Identified
