Comets

The scientists came to the conclusion after examining 'Oumuamua's trajectory.
The dwarf planet was reclassified once before in 2006.
The bad news is, a comet smells like cat pee.
Though both dark matter and dinosaurs are independently fascinating, you might reasonably assume that this unseen physical substance and this popular biological icon are entirely unrelated. And this might well be the case. But the Universe is by definition a single entity and in principle its components interact.
My childhood books on geology had dramatic drawings of volcanoes belching steam into the atmosphere of a prehistoric and still-sterile Earth, suggesting that our planet was born with a subcutaneous reserve of water, waiting to be lanced to the surface by accommodating eruptions. As a kid, that sure seemed reasonable. But it's not true.
(Story continues below.) The cryostat instrument, nicknamed "Himalaya," that researchers used to study the icy conditions
The study will be published in the Feb. 1 issue of the journal Terra Nova. Correction: A previous version of this article
It will be fun to see what turns up in the Rosetta and Philae images and data from Comet 67P/Churyumov-Gerasimenko! Astronomy is always full of surprises when you see something at high resolution for the first time.
Rosetta spacecraft's OSIRIS narrow-angle camera obtained this close-up detail of a smooth region on the "base" of the "body
I've always regarded asteroids as somewhat like dinosaurs: mildly interesting and faintly dangerous. But I'm now thinking that they might be a profitable real estate investment.