Les illustrations d’enfants du système solaire montrent d’ordinaire une Terre plantée au beau milieu de la «zone habitable»: ni trop chaude, ni trop froide. Or, de nouveaux calculs suggèrent qu’elle serait juste sur la ligne.
See on sciencepresse.qc.ca
Astronomers use funny units. We have the light-year, which sounds like a time but is actually a distance. There’s the parsec, a historical (but still used) unit of distance that was famously mis-used as a time in Star Wars.
See on feedproxy.google.com
Gaze upon all of Mercury for the first time ever
by Alasdair Wilkins
The existence of our solar system’s innermost planet has been common knowledge since ancient times, but that doesn’t actually mean we’ve always know much about it. Mercury’s proximity to the Sun has allowed it to jealously guard its secrets, and so this NASA video offers an unprecedentedly detailed view of the planet’s surface.
This video is based on images taken by the MESSENGER probe, the first spacecraft to actually orbit Mercury. It has allowed astronomers to get the first up-close view at the planet’s geology; until now, the sum total of our knowledge was limited to a single Mariner flyby in 1975. Over the past year, MESSENGER has taken over 80,000 images with plans to take 80,000 more. That’s allowed us to assemble this complete visual representation of Mercury’s surface, with each pixel representing about a square kilometer; the video expands on this previously published image…
(see video here: io9)