The energy output from the Sun has increased significantly during the 20th century. But scientits say it is not the key to global warming.
Now, astronomers may have identified the remains from a 2,000-year-old stellar explosion, now considered the oldest supernova on record.
The Milky Way might not have formed through the merger of several smaller galaxies as previously thought, but by some other unknown process, a new study suggests.
With their X-ray vision, and other techniques, researchers are monitoring the chaotic environments around these black holes trying to solve some longstanding mysteries.