What is the longest-period comet we know about?

What is the longest-period comet we know about?
We find out what the biggest impact is on this Galilean moon
We have the answer to this intriguing question
Hint: it doesn’t end well for our planet
The rover’s team is working to restore its sample-drilling capability using new techniques. The latest development is a preparatory test on Mars
Known as “Egg Rock,” the space rock is the first on the Red Planet to be examined with a laser-firing spectrometer
New results from the NASA’s GRAIL spacecraft are providing insights into the huge impacts that dominated worlds of the early Solar System
Astronomers are discovering more intriguing information about the dwarf planet
Is this Saturnian moon really as soft and spongy as it looks?
Just why are those gas giants so much smarter than us? Wait, that’s not what we mean…
What are these floating space rocks made of?