What is a Black Hole?

Monday, May 19th, 2008

From some of my previous posts you know that objects don’t just have size, they have mass. A three-foot diameter ball of loosely packed feathers, for example, has far less mass than a three-foot diameter ball of lead. But if you keep compressing feathers into that three-foot sphere, keep squeezing and squeezing them in, you’ll […]

How long is a light-year?

Monday, May 12th, 2008

You might be surprised to know that a light-year is just one normal Earth year long (a Julian year of 365.25 days)! Confused? Think of it this way, a light-year isn’t a measure of time, but a measure distance within a certain amount of time (a year).
If you’ve kept up with all my other posts on space, you’ll know […]

What is the speed of light?

Saturday, May 10th, 2008

After years of “close” estimates, the speed of light was nailed down to 299,792.458 kilometers per second or 186,282.397 miles per second in 1983. Previous estimates came surprisingly close to the mark given how difficult it must be to put a limit on something as fast as light. We also know that the speed of […]

Why Is The Sky Blue?

Tuesday, April 1st, 2008

What child hasn’t wondered and asked this question. Answering it isn’t all that hard but it helps if you have a good enough understanding of visible light and wavelengths to explain the concept. Lacking that, it’s just important to understand that visible light (there are more spectrums of light than just those you see) comes […]