Monthly Archives: March 2008

Celestial Mechanics

Alessandra Celletti and Ettore Perozzi, Celestial Mechanics: The Waltz of the Planets. This is a semi-popular look at one of my old and persistent interests. Very little math, but a lot of graphs and terminology. It includes the traditional subjects, e.g. tidal forces, the discovery of Neptune, Delaunay’s lunar theory, and the stability of the solar system. but the emphasis is on modern developments, e.g.

  • Modern dynamical systems theory and chaotic motion.
  • Trojan satellites and Lagrange Points–L1 can actually be useful, even though it is unstable.
  • Artificial satellites and space travel, including Hohmann transfer orbits.
  • Planetary ring systems.
  • The Kuiper belt, the outer solar system, and the demotion of Pluto from planetary status (correct, IMHO).
  • Planets around other stars.

A unifying theme is the importance of resonant orbits. For example, Neptune makes three orbits around the Sun in about the same number of years as Pluto makes two. This is not a coincidence.

Recommended for those with some general knowledge of astronomy.

Terrifying, sad, … but funny as well

(OK, I have a twisted mind)

THE CRUDDIEST MOMENT OF THE CRAPPIEST DAY OF MY LIFE ON EARTH happened as I found myself watching five televisions simultaneously, each containing a different political pundit opining on the same subject. When I looked down toward my computer screen to see what the bloggers were saying about it, I noticed that a button on my shirt had come undone.

The beginning of Cruel and Usual Punishment. Via the Inverse Square Blog

They knew it was coming

From the Daily Mail: Family holidays ruined by earliest Easter in 90 years

God Plays Dice refers to this column, introducing a nice discussion of how the date of Easter is calculated. At the end of it she refers back to it, commenting

And I have no sympathy for the people quoted in that article. They’ve known this was coming since 1752, when the UK changed over to the Gregorian calendar.

Via Slashdot

A visitor to Assisi

Mikhail Gorbachev admits he is a Christian

Mikhail Gorbachev is a Christian say Franciscan friars

Via The Angels are in the Details, which asks some good questions and comments:

This going to be a major shock for the old “Gorby is the Antichrist” crowd. Or maybe not. After all, it seems that Gorbachev has embraced an ancient, liturgical form of the faith.