BALTIMORE, Oct. 14 (UPI) -- U.S. astronomers think they have solved the four-century-old mystery of a supernova observed by German astronomer Johannes Kepler.
On Oct. 9, 1604, sky watchers -- including Kepler, who is best known for discovering the laws of planetary motion -- were startled by the sudden appearance in the western sky of a new star that rivaled the brilliance of the nearby planets.
When the bright object -- now called Kepler's supernova remnant -- appeared alongside Jupiter, Mars, and Saturn that evening, observers had only their naked eyes with which to study it because the telescope would not be invented for another four years.
Johns Hopkins University astronomers Ravi Sankrit and William P. Blair have used the Spitzer Space Telescope, the Hubble Space Telescope and the Chandra X-ray Observatory to locate the phenomenon and analyze its appearance in infrared radiation, visible light and X-rays.
The resulting combined image unveils a bubble-shaped shroud of gas and dust that is 14 light-years wide and still is expanding at 4 million miles per hour (2,000 kilometers per second), even after 400 years. The cloud, the astronomers said, is a fast-moving shell of iron-rich material from the exploded star surrounded by an expanding shock wave that is sweeping up interstellar gas and dust.
