http://citizenscientistsleague.com/

Welcome to the World of Hands on Science
“The Citizen Scientists League promotes responsible scientific observation, experimentation,
discovery, and invention. We encourage active participation, networking and publishing
by science enthusiasts at all levels of education and experience.”

# Skill Builder: Advanced Arduino Sound Synthesis

The Arduino is an amazing platform for all kinds of projects, but when it comes to generating sound, many users struggle to get beyond simple beeps.

http://en.wikipedia.org/wiki/Twos_complement

# Two’s complement

(Redirected from Twos complement)

Two’s complement is a mathematical operation on binary numbers, as well as a binary signed number representation based on this operation. Its wide use in computing makes it the most important example of a radix complement.

http://playground.arduino.cc/Code/BitMath

### The Binary System

To better explain the bitwise operators, this tutorial will express most integer values using binary notation, also known as base two. In this system, all integer values use only the values 0 and 1 for each digit. This is how virtually all modern computers store data internally. Each 0 or 1 digit is called a bit, short for binary digit.

In the familiar decimal system (base ten), a number like 572 means 5*102 + 7*101 + 2*100. Likewise, in binary a number like 11010 means 1*24 + 1*23 + 0*22 + 1*21 + 0*20 = 16 + 8 + 2 = 26.

# Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2013 September 7

Night in the Andes Ice Forest
Image Credit & Copyright: Babak Tafreshi (TWAN)
Explanation: This forest of snow and ice penitentes reflects moonlight shining across the Chajnantor plateau. The region lies in the Chilean Andes at an altitude of 5,000 meters, not far from one of planet Earth’s major astronomical observatories, the Atacama Large Millimeter/submillimeter Array. Up to several meters high, the flattened, sharp-edged shapes, and orientation of the penitentes tend to minimize their shadows at local noon. In the dry, cold, thin atmosphere, sublimation driven by sunlight is important for their formation. A direct transition from a solid to a gaseous state, sublimation shapes other solar system terrains too, like icy surfaces of comets and the polar caps of Mars. Above the dreamlike landscape stretches the southern night sky. Their own forms rooted in myth, look for the constellations Pegasus, Andromeda, and Perseus near the panorama’s left edge. Bright and colorful stars of Orion the Hunter are near center, with the Large Magellanic Cloud and the South Celestial Pole on the far right.

Tomorrow’s picture: menacing cloud

Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
NASA Official: Phillip Newman Specific rights apply.