Science of the Physical Universe 30: Life as a Planetary Phenomenon

Formerly … Science Core A-54: Life as a Planetary Phenomenon Instructor: Dimitar Sasselov

Instructor: Dimitar Sasselov Teaching Fellows: Wade Henning (Head TF), Darin Ragozzine, Li Zeng, Jessica Haurin, Maggie McLean Science of the Physical Universe 30: Life as a Planetary Phenomenon

1.Course structure 2.Grading 3.Organizational matters Science of the Physical Universe 30: Life as a Planetary Phenomenon

Course Structure: 5 themes 1.The Origin and Evolution of Planets 2.The Origin and Evolution of Life 3.Exploring the Solar System for Life 4.Searching for Life beyond the Solar System 5.Extraterrestrial Intelligence

1.Course structure 2.Grading 3.Organizational matters:  Midterm Exam - on March 3 or 8-th ?  Sections Science of the Physical Universe 30: Life as a Planetary Phenomenon

TEXTBOOKS: Science of the Physical Universe 30: Life as a Planetary Phenomenon

Opportunities for Undergraduates at Harvard Undergraduate Research Fellowships Individual awards of up to $2,000 are available for Harvard undergraduates for research during the academic year. Summer Undergraduate Research Fellowships Funding Summer Undergraduate Research Grants of up to $5,000 are available for undergraduates working in Origins team member labs on Origins-related projects. For more information on any of these programs, please contact: Carol Knell, Origins Program Coordinator, at

The discovery of Kepler’s first rocky planet (announced Jan. 9, 2011) Radius: 1.4 Earth Earth

Lecture 2: In the Beginning: Origins of the Elements 1.The Periodic Table: elements and isotopes 2.Synthesis of elements in the Early Universe 3.Stars: making the “elements of life” 4.We are made of star stuff.

What is the Universe made of ?

13 NASA Hubble Space Telescope - Jan. 2010

14 Millenium Run, Springel et al. 2006

The Periodic Table

Electron Orbits in Atoms

The Periodic Table

Electron Orbits in Atoms

Plots of electron density shapes of 1s, 2p and 3d orbitals:

The Periodic Table … in terms of electron subshells:

The Periodic Table … the elements of Earth life:

Lecture 2: In the Beginning: Origins of the Elements 1.The Periodic Table: elements and isotopes 2.Synthesis of elements in the Early Universe 3.Stars: making the “elements of life” 4.We are made of star stuff.

Looking Back into the Past Hot Dense Smooth Cold Thin Clumpy

Looking Back into the Past NASA’s WMAP mission mapped the sky in microwaves

Looking Back into the Past False-color map of the temperature fluctuations seen by measured by WMAP. This pattern appears to be random, but it is the superposition of waves of different size. It is like a fingerprint. The pattern seen is consistent only if 75% of H and 25% of He constitute the gas.

Stars like our Sun expand and disperse their envelopes It takes 3 to 10 Ga for the the synthesis of light and heavy elements in these stars. Their envelopes are rich in heavy elements - yet, especially in C, N, and O. Eventually new stars are formed from this gas. How do we know that ? a)We see the spectral signatures of these newly synthesized elements in their light.

The most massive stars end their thermonuclear cycles as Supernovae Supernova 1994D: the bright explosion of a star in the outskirts of a distant galaxy. During the explosion, in a matter of minutes, hours and days, large quantities of iron and other heavy elements are synthesized.

The most massive stars end their thermonuclear cycles as Supernovae During the explosion, in a matter of hours and days, large quantities of iron and other heavy elements are synthesized. How do we know that ? a)We see the spectral signatures in the light from the explosion; b)Computer models reproduce measured isotopic ratios in Solar System objects and other stars.

We are made of star stuff By mass - Human body: H = 10%, He = 0%, C = 18%, N = 3%, O = 65%, Ca = 2%, Fe = 0.004%. Earth’s crust: H = 1 %, He = 0%, C = 2%, N = 0%, O = 47%, Si = 26%, Ca = 3%, Fe = 5% Sun & stars: H = 71%, He = 27%, all other elements = 2% (with O most abundant).

The Periodic Table … the elements of Earth life:

Main points to take home: 1) Elements: def. by protons in atom (90 stable); Isotopes: def. by neutrons in atom (266 stable) The Periodic Table of the Elements allows the analytical description of all species of mineral or biological origin. 2)There are 2 main sources of their origin: a) H, He, & Li were synthesized ~13.7 Ga ago in the Early Universe; b) stars transform H & He into all the rest. 3) Planets and life are here thanks to many past generations of stars.

The Periodic Table

We are made of star stuff By mass - Human body: H = 10%, He = 0%, C = 18%, N = 3%, O = 65%, Ca = 2%, Fe = 0.004%. Plants: H = 10%, He = 0%, C = 3%, N = 0.3%, O = 79%, Ca = 0.1%, Fe = 0.02%. Earth’s crust: H = 1 %, He = 0%, C = 2%, N = 0%, O = 47%, Si = 26%, Ca = 3%, Fe = 5% Sun & stars: H = 71%, He = 27%, all other elements = 2% (with O most abundant).