IC 418 IC 418 IC 418, also known as Spirograph Nebula, is a planetary nebula in the Milky Way Galaxy. The name derives from the intricate pattern of the nebula, which resembles a pattern which can be created using the Spirograph, a toy that produces geometric patterns (specifically, hypotrochoids and epitrochoids) on paper. Only a few million years ago, IC 418 was probably a common red giant star. Since running out of nuclear fuel, though, the outer envelope has begun expanding outward leaving a hot remnant core destined to become a white dwarf star. IC 418 lies about 3600 light-years away and
Geometric probability sophisticated branch of multivariate calculus. Stochastic geometry emphasises the random geometrical objects themselves. For instance: different models for random lines or for random tessellations of the plane; random sets formed by making points of a spatial Poisson process be (say) centers of discs. Geometric probability Problems of the following type, and their solution techniques, were first studied in the 18th century, and the general topic became known as geometric probability. For mathematical development see the concise monograph by Solomon. Since the late 20th century the topic has split into two topics with different emphases. Integral geometry sprang from the principle