1. “Being Milutin Milankovitch”Or
“From Millennia to Hours: The Decreasing Scales of the Orbital Theory of Multin Milankovitch”
Adapted from
Dr. Randy Cerveny
Presidential Professor, ASU

2. Milankovitch Theory
Milutin Milankovitch, Serbian mathematician and astronomer
In 1938, hand-computed insolation at 65° N based on orbital variations for two 6-month seasons (summer & winter)

3. Milankovitch Theory
He computed variations in three primary orbital parameters:
Tilt
Eccentricity
Precession of the Longitude of Perihelion in relation to the Moving Equinox (“Precession”)

4. Milankovitch Theory Tilt
The variations in the axial tilt of the Earth.
This orbital component has a cycle of 42,000 years for the Earth to shift from an axial tilt of 22.1° to 24.5° and back

5. Milankovitch Theory Eccentricity
The variations associated with the shape of the Earth’s orbit (oblique to circular)
The primary cycle of eccentricity is 93,000 years with a secondary cycle at 400,000 years.

6. Milankovitch Theory Precession Most complex of the three mechanisms.
Refers to the season in which perihelion is occurring as a function of the orientation (or “wobble”) of the Earth’s axis

7. Milankovitch Theory Current Precession
Earth’s perihelion in early January given the current axial orientation towards the star Polaris
But 11,000 years from now, perihelion will occur in July
The primary cycles for precession are 19,000 and 23,000 years.

8. Two huge problems in gaining acceptance for his theory
No reliably-dated evidence
Unknown which dates were the most important
Theory put on back burner until more evidence gathered...

9. CLIMAP & the ocean corers
International project in mid-1970s
Help better understand when the last ice age occurred
Includes two important research thrusts
First, a chronology of past climates was begun using deep-sea marine cores.

10. Hays, Imbrie & Shackleton: Pacemaker to the Ice Ages
Spectral analyses of cores suggested existence of distinct correlation.
Closely matched the cycles computed by Milankovitch for the Earth’s three orbital mechanisms.

11. Producer vs. consumer?
Remember a producer is a organism that makes a certain chemical.
A consumer is an organism or thing that uses a certain chemical.