Astronomers at MIT have observed unusual black hole X-ray flashes that are accelerating in frequency. A white dwarf star near the black hole might be the cause.
What is a variable star? It's a star that brightens and dim in a cycle that might last hours, or weeks, or months, or longer. Astronomers know millions!
On January 14, 2005, the Huygens spacecraft descended through the atmosphere of Saturn's moon Titan and landed on its surface. See the images of Titan.