Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. CNN  —  A NASA spacecraft has intentionally slammed into an asteroid in humanity’s first test of planetary defense. The impact occurred at 7:14 p.m. ET greeted by cheers from the mission team in Laurel, Maryland. The DART mission, or the Double Asteroid Redirection Test, launched 10 months ago. While the asteroid, Dimorphos, was not at risk of impacting Earth, this demonstration could determine how to deflect space rocks that could pose a threat to Earth in the future. “We’re embarking on a new era of humankind, an era in which…