We have no idea what it might be.
An unprecedented cosmic observation.
There go our hopes of nuking an apocalyptic asteroid.
Here are some highlights from its journey
The survey also confirmed the existence of two other moons, whose discovery was announced last year
What's the matter with dark matter?
Plus: new insights into the planet's interior.
It's just plane confusing.
In the December 1980 issue of Popular Science, a 38-year-old theoretical physicist answers the ultimate question about the universe.
And it's much bigger than we expected.
But we'll have to get there first.
The Saturn explorer's death spiral begins on Sunday
Astronomers catch a galaxy magnifying and splitting the light from a supernova
Hawking radiation observed in a homemade black hole analogue
LIGO experiment reports a second successful discovery
And other experiments launching to the International Space Station this month
Fortunately it's not headed for Earth
Piping hot Jupiter fries, please!
Short answer: It depends who you ask
After nine years and three billion miles, here's what we're learning from it all
Even though I helped demote it
Witness history in the making
It's been hiding under debris for billions of years