Nasa are set to reveal an "amazing" discovery on Thursday, according to one of the space agency's senior scientists.
Whilst speaking about the latest images of Pluto captured by the New Horizons probe, Stern said: "Nasa won't let me tell you what we're going to tell you on Thursday. It's amazing."
Last week, Nasa unveiled new images of the surfce of Pluto, which show a landscape of mountains, craters and gorges.
As reported by The Guardian, Stern said: "This world is alive."
"It has weather, it has hazes in the atmosphere, active geology... Every week I am floored."
There is no word yet on what the announcement could be, with Nasa taking the same line of secrecy as they did at their last big event - the announcement of the discovery of water on Mars.
However, a number of unknowns remain. Pluto has vast mountainous dune fields, a multicoloured surface, and a number of other mysterious features that have not been explained by science.
Thursday's announcement could relate to any one of these.
Nasa has had a year of big discoveries. From the discovery of flowing water on Mars, to the identification of 'Earth 2.0' - Kepler 452b, the most Earth-like planet every discovered - the leading space agency has been holding momentous announcements fairly regularly over the last few months.
As Stern said, "2015 will be a year in textbooks forever," as the year in which mankind discovered so much about its solar system.
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