The Great Comet Of 1881  -   Étienne Léopold Trouvelot  1881

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!!

Jupiter and beyond the Infinite…

4 hour star trails timelapse at Point Reyes

Blue Spot. West Coast New Zealand. 

1705 Halley Documents Comet British astronomer Edmund Halley predicted the return of the comet that we now call Halley’s comet. He documented historic comet sightings and found patterns that led him to theorize that comets, which until then were considered baffling and even potentially dangerous because of their irregularity, actually had calculated orbits around the sun and would return periodically. He believed that the comets witnessed in 1531, 1607, and 1682 were actually the same comet and predicted it would return in 1758. Even though Halley died in 1742 the comet arrived on schedule and later became known as Halley’s Comet.

Eclipse News at AstroTidbits

Don’t know how to prepare for the coming total eclipse of the sun?  Get some info at http://www.astrotidbits.com and be ready.

Infrared Jupiter looks hot as Juno spacecraft approaches

NASA’s mission to explore the Jovian system has almost reached its destination, and telescopes on Earth are capturing some especially fiery images of the planet to help.

This “Pyrite Sun” may look like a sand dollar, but it is actually a concretion that was found in Illinois. 

The NASA Village

Today in the NASA Village… Environmental Monitoring: How Clean is it?

So, the International Space Station has been operating for 16 years now. Do you wonder how clean is the air astronauts breathe or the surfaces that the astronauts touch each day? Are there hazardous levels of bacteria or other toxic components in the drinking water supply? Obviously on this (18+ year) long duration endeavor, we have to monitor the air quality, the microbial content of the air, surfaces, and water, the sound levels we are experiencing, and the radiation doses that we are being exposed to. These data are not only critical for safety of the astronauts while on board, but for long term occupational health monitoring. Future deep space explorers will benefit from lessons we are learning now. 

Needless to say, there are some specialized pieces of hardware that we have to know how to operate in order to perform this environmental monitoring. Elisca Hicks first joined NASA by working in the Education and Outreach Program. She later transitioned to the Space Medicine Training team in 2005. Elisca currently has a dual role in the Space Medicine Training Team. She is an instructor, she teaches the environmental monitoring hardware to Space Station crew members, but she also coordinates multiple medical student and doctor programs at Johnson Space Center. 

This media slide containing mold is what Elisca teaches us to use. This helps us identify if there are issues or areas that need our additional attention.

This picture shows mold found growing on a kit that was being used in an experiment. Inside the kit were tubes that contained a swab and liquid in them. The tubes were damaged (cracked lids) and they leaked, causing the mold to grow on the kit.

Here Elisca is showing me how to place the media tray in the microbial air sampler.

Consider that the lack of gravity means that dust does not collect just on the upper surfaces, but on all the surfaces. The ventilation system moves a lot of the debris to the filters, but electrostatic forces result in the potential for debris to collect pretty much anywhere. The worst air quality can be seen when the callouses of the crew members feet begin to come off about month 2. Remember, we are not using the bottoms of our feet for walking, so we actually get callouses on the tops of our toes from sliding them under handrails!

Next time on the NASA Village… You Need to Experience It.

Do you want more stories? Find our NASA Villagers here!

The Clansman PRC-320 - Plessey RT-320 Military Manpack Transciever [HD] - M0VST (by markbeermonster)