Astronomy Cast 4.1: Heisenberg Uncertainty Principle (Episode 252)

Particles aren't just little bundles of matter that fly around, they're waves.  This means that have a wavelength that gets refracted and interacts with the material around it.  After this realization that particles are also waves, trying to describe what they do and where they are was so different, that scientists had to rethink everything they had already established.  This wave-like property brought up the problem of trying to determine the position of a wave because combining the wavelengths and velocities to determine the position, it gets lost because there are no limits on the momentum of the wave, so we no longer know where it is.
So, what Heisenberg came up with was that it is impossible to know both the position and momentum of a particle at any given moment because the more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.  Further, Heisenberg argued that such concepts as orbits of electrons do not exist in nature unless and until we observe them.  This is because one cannot know the precise position and momentum of a particle at a given instant, so its future cannot be determined; one cannot calculate the precise future motion of a particle, but only a range of possibilities for the future motion of the particle.
Heisenberg's principle does not state that everything is uncertain, just that there are limits to certainty and uncertainty when dealing with objects at the subatomic level.

APOD 4.4

Antares and Clouds (April 17, 2012)

The star on the leftm covered in a yellow cloud o dust, is Antares in the constellation Scorpius.  It is about 550 light-years away, and 850 times the diameter of our Sun, 15 times more massive, and 10,000 times brighter.  The blue star on the far right is Al Niyat.

APOD 4.3

Paris by Night (March 31, 2012)

This picture, taken on March 25, depicts the city lights of Paris, but also the conjunction between Venus, Jupiter, and a crescent moon.
This same conjunction could be seen in other parts of the world, too.  For example, I saw it in Sarasota, Florida.
At the moment, there are four planets that are visible in the sky: Jupiter, Venus, Mars, and Saturn.

APOD 4.2

Centaurus A (April 4, 2012)

This is an image of the galaxy Centaurus A, the closest active galaxy to Earth.  It's about 11 million light-years away and spans over 60,000 light-years.  This elliptical galaxy was most likely formed from the collision of two other galaxies.  At the center of the galaxy there is a black hole with a billion times the mass of the sun that is consuming cosmic debris.