What Are Comets Made Of?

Saturn’s moon, Daphnis, and Saturn’s rings.

Lots of stuff like this at www.astrotidbits.com with explanations.

How do we know light is a wave?

Before I answer this question, I’ll need to briefly go over a wave property called superposition. Basically, superposition is the idea that two waves can be in the same position at the same time, and interfere with each other:

When the two waves add to each other and make a larger wave, we call this constructive interference. When the waves cancel each other out, we call this destructive interference. 

Now we’re going to move on to the Double Slit Experiment. Basically, you shine a beam of light at a piece of metal, cardboard, etc with two slits in it, with a surface behind it where you can see the light hit it. 

If light is a wave, what we’d expect to see would be an interference pattern created by the light from the first slit interfering with light from the second slit, which is exactly what we see. It’s a pattern of constructive interference (brighter regions) and destructive interference (darker regions), looking like this:

These images are helpful:

that is how we know light acts as a wave!!

Goodbye to M42 for this year.  But I’ll see you again in November.  Meanwhile I can look at this picture I took in January of this year.

www.astrotidbits.com

Our planet seen from Saturn, captured by the Cassini spacecraft

Image credit: NASA / Cassini

Ham radio operator taking part in a field day

(Walter B. Lane. 1946)

Comet 67P/C-G is framed by one of Rosetta’s solar wings, which is 46 feet long. A stream of gas and dust extends from an active area of the comet’s neck, about 10 miles away. (via NY Times)

Escape velocity

A snippet from a full page graphic - vintage scientific illustration c.1960

Fading Females

As the daughter of our town’s E.S.D.A. Coordinator, I have always been intrigued by ham radio. My father (and elmer) has been a ham for about 40 years. He actually received his license when he was in high school!

After studying for three weeks, I went to take the ham test. I was very discouraged to see that I was the only girl in the room. However, I was treated like a queen by the group that was hosting the test. They seemed excited to have a female in their midst.

Upon receiving my Technician license, I eagerly awaited the Tuesday night ARES net (which my dad happens to be the Net Control of). Again, I was saddened to hear but a few female voices. Over time, I noticed that the female hams rarely checked in to the net. I wondered why these women who worked so hard to achieve their licenses would not want to take advantage of all that ham radio has to offer.

I hope that women are being encouraged to be active hams. Whether they join a club or simply make contacts, females are providing a fresh voice and perspective to the hobby. So, ladies, do not be shy! Proudly check in with your call sign. You have earned it!