Something big and bright happened on Mars, but what was it?
In March 2012, amateur astronomers captured something big and bright coming off the surface of Mars. Estimates measured the object to be about 193 kilometers tall and as many as 966 kilometers wide. In a new paper published in Nature, scientists are speculating that the giant plume could be made of frozen CO2 or water, or maybe the phenomenon is the result of an aurora that would put Earth’s northern lights to shame. PopularScience reports that neither of those hypotheses seems to match what’s known about the martian atmosphere however, and further study will be required to solve the mystery for sure.
Passing stars can perturb the Oort Cloud, triggering comet showers and potentially extinction events on Earth. We combine velocity measurements for the recently discovered, nearby, low-mass binary system WISE J072003.20-084651.2 ("Scholz's star") to calculate its past trajectory. Integrating the Galactic orbits of this ~0.15M⊙binary system and the Sun, we find that the binary passed within only 52+23−14kAU (0.25+0.11−0.07pc) of the Sun 70+15−10kya (1σuncertainties), i.e., within the outer Oort Cloud. This is the closest known encounter of a star to our solar system with a well-constrained distance and velocity. Previous work suggests that flybys within 0.25 pc occur infrequently (~0.1 Myr−1). We show that given the low mass and high velocity of the binary system, the encounter was dynamically weak. Using the best available astrometry, our simulations suggest that the probability that the star penetrated the outer Oort Cloud is ~98%, but the probability of penetrating the dynamically active inner Oort Cloud (<20 is="" kau="" span="">−4. While the flyby of this system likely caused negligible impact on the flux of long-period comets, the recent discovery of this binary highlights that dynamically important Oort Cloud perturbers may be lurking among nearby stars.20>