Top Science Story No. 60: The Lopsided Red Planet

Top 100 Stories of 2008 #60: Mars Became Lopsided After Massive Asteroid Collision
Discover Magazine

“For more than 30 years, astronomers have known that Mars is lopsided. The southern highlands, which cover about two-thirds of the planet, are about two and a half miles higher than the northern plains. But until now, whether the disparity was caused by an asteroid impact or volcanic action on the surface has been in dispute. Three papers published in June in Nature together made a convincing case that a collision left a lasting scar on the planet’s northern half.”