EQUINOX AURORAS: Northern autumn has begun, and that means it's aurora season around the Arctic Circle. Equinox cracks in Earth's magnetic field are allowing solar wind to penetrate the magnetosphere, energizing the Northern Lights. "Hooray for Northern Autumn!" says Thomas Kast who saw an impressive display last night in Oulu, Finland. "It's impossible to sleep with these images in my mind." Browse the aurora gallery for more. Free: Aurora Alerts

ROBOTS LAND ON ASTEROID RYUGU: This weekend, Japan made history by deploying two rovers on the surface of a near-Earth asteroid. The mechanical explorers dropped from their mothership, Hayabusa2, less than 100 meters above Ryugu, and now they are hopping across the space rock's cratered landscape. This picture was taken by Rover-1A in mid-hop:

Hopping is necessary because the asteroid's gravity is too weak for simple rolling.  Instead of wheels, the rovers have rotating motors inside that allow them to shift their momentum and, thus, make little jumps across the asteroid's rugged surface. Mission controllers are taking great care that the rovers, which measure 18 cm by 7 cm and weigh only 1 kg, do not fly into space.

As historic as this achievement is, it is only the beginning: Rover-1A and 1B are on a reconnaissance mission for two more robots slated to land later this year.  In October, Hayabusa2 will release MASCOT (Mobile Asteroid Surface Scout), a larger lander made by the German Aerospace Center. MASCOT will be followed, in turn, by another Japanese robot.

Above: Hayabasa2 photographs its own shadow on the asteroid. Credit: JAXA