Astronomers have discovered that the sun had a close encounter with two blazingly hot massive stars around 4.4 million years ago. The discovery was made thanks to a "scar" left by the event in swirling clouds of gas and dust just beyond the solar system. Not only does this research reveal more about the solar system's immediate celestial environment, but it could also shed light on how surrounding features in that environment played a role in the evolution of life on Earth.
To make this discovery, the team of astronomers had to take into account the motions of these "local interstellar clouds," which stretch out for around 30 light-years, the sun, and the intruder stars, which now dwell 400 light-years from Earth in the front and rear "legs" of the constellation Canis Major (the Great Dog). That's tricky because the sun alone is rocketing through space at 58,000 miles per hour (93,000 km/h), or about 75 times as fast as the speed of sound at sea level here on Earth.
