Create Your Own Spirograph

Spirograph Java Applet Created by Anu Garg.

What is a Spirograph?

A Spirograph is formed by rolling a circle inside or outside of another circle. The pen is placed at any point on the rolling circle. If the radius of fixed circle is R, the radius of moving circle is r, and the offset of the pen point in the moving circle is O, then the equation of the resulting curve is defined by:

	x = (R+r)*cos(t) - (r+O)*cos(((R+r)/r)*t)
	y = (R+r)*sin(t) - (r+O)*sin(((R+r)/r)*t)

Here is how you can use the controls in this Spirograph applet:

• The first three scroll bars in the control panel let you change R, r and O respectively. You can change these values between 1 and 100.

• You can use the next three scroll bars to change the color of the drawing. These scroll bars change the red, green and blue values of the color (in the range 0-255) respectively.

• The last scroll bar lets you choose the number of iterations for the Spirograph.

• You can use the Random button to select random values for the radii and color. The number of iterations is not changed by the Random button.

The Beautiful Dying Star

"Garden-variety stars like our Sun live undistinguished lives in their galactic neighborhoods, churning out heat and light for billions of years. When these stars reach retirement age, however, they become unique and colorful works of art. As ordinary, sun-like stars begin their 30,000-year journey into their twilight years, they swell and glow, shrugging off their gaseous layers until only their small, hot cores remain.

  The ejected gaseous layers are called planetary nebulae, so named in the 18th century because, through small telescopes, these gas clouds had round shapes similar to distant planets such as Uranus or Neptune.

The gaseous debris glows like a fluorescent design, producing objects with striking shapes and names like "The Ring Nebula" and "The Spirograph Nebula." Astronomers have recorded more than 1,000 of them in our galaxy."

From "The Glorious End Of Stellar Life", STScI Astrofile

Planetary Nebulae Galleries

Raghvendra Sahai and John Trauger's (JPL) Planetary Nebulae Gallery

Arsen Hajian and Yervant Terzian's (USNO) Planetary Nebulae Gallery

STScI Planetary Nebulae Gallery

Bruce Balicks's (U. Washington) Planetary Nebulae Gallery

Robin Ciardullo's (Penn State) Planetary Nebulae Gallery