In 2015, 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.
The ancient planet 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.
A Revolutionary New Look at How Planets Are Born
HL Tauri, an infant star in the constellation Taurus, is surrounded by a swirling disk of gas and dust. The dark rings mark places where planets are forming. Right there, right now! (Credit: ALMA (ESO/NAOJ/NRAO)
It truly is revolutionary, Or you could call it the holy grail, or the smoking gun–almost any cliche you throw at it works, because this is the real deal. What you are witnessing here is nothing less than the genesis of an entire new solar system, taking place right before your eyes. For some quick context: Ever since Immanuel Kant introduced his nebular hypothesis in 1755, scientists have strongly suspected that planets form in swirling clouds around newborn stars. Over the years the theory has grown far more refined, filled in with supercomputer simulations and with increasingly detailed studies showing that young stars are surrounded by disks of gas and dust, closely matching what the models predict. But this new image, created by the ALMA observatory in Chile, is by far the best look ever at how planets are born.