EarthSky News - March 22 - Death by Black Hole

March 22 Death by Black Hole by:

Star's death spiral into black hole What happens when a star with about our sun's mass spirals into a black hole? With the distant event known as ASASSN-14li, astronomers have figured out some details. Tonight … Is Sirius the most luminous star? To astronomers, the word "luminous" refers to a star's intrinsic brightness. Sirius is our sky's brightest star, but only because it's relatively nearby at 8.6 light-years away. What is stellar magnitude? Brightest stars to the eye are 1st magnitude, and dimmest stars to the eye are 6th magnitude. How the magnitude scale works in astronomy and why it's useful. Lenticular clouds look like UFOs Glorious photos of rare lenticular clouds, sometimes called UFO clouds, plus a word about how they form.

Order your EarthSky Planisphere today! A planisphere is virtually indispensable for beginning stargazers. Your support means the world to us.

Green flash at sunset It's easiest to see a green flash with optical aid, but you have to be very careful not to look too soon, or you'll dazzle - or damage - your eyes. Image via Mike Busch of GreatSouthBayImages.

Is Sirius the most luminous star? Sirius is so bright that many notice it twinkling in different colors. Amanda Cross in England wrote: "This is Sirius twinkling different colors through the atmosphere. Images were taken deliberately out of focus, using a high ISO and low shutter speed to pick up the colors. There are 31 images taken 25 seconds apart and stacked using StarStaX." Submit your photo to EarthSky here!

by: