Not Your Parents’ Solar System!

Dr. Frank Summers Space Telescope Science Institute

July 11, 2013

Your Ancient Ancestors’ Solar System

Earth

Moon

Mercury

Venus

Sun

Mars

Jupiter

Saturn

Claudius Ptolemy 150 – Almagest

Misconception

•  Ptolemy invented the Earth-centered solar system.

Misconception

•  Ptolemy invented the Earth-centered solar system.

•  Ptolemy organized and systematized the Earth-centered solar system based on ideas that had been developed over about 600 years.

Your Parents’ Solar System

Nicholas Copernicus 1543 – On the Revolutions of Heavenly Spheres

Misconception

•  Copernicus delayed publishing because he feared criticism from religious leaders.

Misconception

•  Copernicus delayed publishing because he feared criticism from religious leaders.

•  Copernicus delayed publishing (in part) because he feared criticism from scientists.

Earth

Moon

Mercury

Venus

Sun

Mars

Jupiter

Saturn

Sun

Mercury

Venus

Earth / Moon

Mars

Jupiter

Saturn

Misconception

•  Copernicus’ Sun-centered solar system was quickly accepted because it was much simpler and more accurate.

Misconception

•  Copernicus’ Sun-centered solar system was quickly accepted because it was much simpler and more accurate.

•  Copernicus’ Sun-centered solar system was just as complex as Ptolemy’s Earth-centered solar system, and provided no more accuracy in its predictions.

Galileo 1609 – Use of telescope for astronomy

1632 – Trial by the Inquisiton

Misconception

•  Galileo invented the telescope and was the first to use it for astronomy.

Misconception

•  Galileo invented the telescope and was the first to use it for astronomy.

•  Galileo was one of several folks who improved the spyglass so that it could be used for astronomy.

Misconception

•  Galileo proved that Copernicus’ Sun-centered solar system was correct.

Misconception

•  Galileo proved that Copernicus’ Sun-centered solar system was correct.

•  Galileo tried to prove Copernicus’ Sun-centered solar system, but his arguments were wrong.

Tycho Brahe 1546-1601

Johannes Kepler 1571-1630

Misconception

•  Astronomers embraced the Sun-centered solar system because it is philosophically simpler.

Misconception

•  Astronomers embraced the Sun-centered solar system because it is philosophically simpler.

•  Astronomers embraced the Sun-centered solar system only when it could provide better predictions.

Isaac Newton 1687 – Principia

William Herschel 1781 – Discovery of Uranus

1801 – Planet Ceres (Piazzi)

1801 – Planet Ceres (Piazzi)

1802 – Planet Pallas (Olbers)

1804 – Planet Juno (Harding)

1807 – Planet Vesta (Olbers)

1845 – Planet Astraea (Hencke)

Urbain Le Verrier & John Couch Adams 1846 – Prediction and discovery of Neptune

Rocky Planets Giant Planets

Misconception

•  You can’t just demote a planet!

Misconception

•  You can’t just demote a planet!

•  In the mid-1800’s, astronomers demoted the many planets between Mars and Jupiter to be asteroids.

Clyde Tombaugh 1930 – Discovery of Pluto

Misconception

•  Pluto’s discovery relied on mathematical predictions based on perturbations in Neptune’s orbit.

Misconception

•  Pluto’s discovery relied on mathematical predictions based on perturbations in Neptune’s orbit.

•  Pluto’s discovery relied solely on the incredible observing skill and dedication of Clyde Tombaugh. – Neptune’s orbit shows none of the claimed

perturbations.

Your Parents’ Solar System

Your Parents’ Solar System

Your Parents’ Solar System

Mercury Venus

Earth Mars

Jupiter Saturn

Uranus Neptune

Pluto

My Very

Energetic Mother

Just Served

Us Nine

Pizzas

Facts Are Not Knowledge

•  Memorization, not understanding •  Factoids •  Highlights differences •  Little or no relevance •  Little or no “big picture”

Comparative Planetology

An Improvement

•  Compare and contrast – Discuss broad ideas – Apply to planets, moons, etc., as a group

•  Highlight similarities – Appearance – Characteristics – Events

April 1997 September 1997

Planetary Comparisons •  Canyons – Grand Canyon, Mariner Valley •  Volcanoes – Mount St. Helens, Olympus

Mons, Io •  Craters – Earth, Moon, Mercury, …

•  Storms, Winds, Seasons, Weather, Ice Floes, Magnetic Fields, Moons, Rings, etc

Comparative Planetology

•  Messages – What happens on Earth happens

elsewhere – Solar system is understandable

•  Pieces to assemble the big picture

Sun

Rocky Planets

Asteroid Belt

Giant Planets

Kuiper Belt

Oort Cloud

The 21st Century Solar System

Families of the Solar System

•  Classes of similar objects – Size – Composition – Orbit size – Orbit shape – Orbit inclination – Moons – Rings

Hollywood’s View of the Asteroid Belt

Scientific View of the Asteroid Belt

960 million miles

Hundreds of thousands of asteroids …

… about a million miles apart!

Sizes of the Giant Planets and Earth

Kuiper Belt

Oort Cloud •  Billions of icy minor

planets – comet nuclei •  Roughly spherical out

to 50,000 AU •  Predicted by Jan Oort •  Explains long-period

comets

Figure 1a: Comet Semimajor Axis Distribution

0

100

200

300

400

500

600-0

.004

-0.0

02

0.00

0

0.00

2

0.00

4

0.00

9

0.02

0

0.04

2

0.08

8

0.18

5

0.39

0

1 / a (1/AU)

Num

ber

of C

omet

s

Short PeriodLong Period

Orbital Period: 200 years∞ 7 years

Families of the Solar System

•  Classification •  Structure of the solar system

– Similar objects lie in similar regions •  Clues to solar system formation and

evolution

Sun

Rocky Planets

Asteroid Belt

Giant Planets

Kuiper Belt

Oort Cloud

Sun

Oort Cloud

Mercury Venus Earth Mars

Asteroid Belt

Jupiter Saturn Uranus Neptune

Kuiper Belt

Some

Others Cheer

May View Elaborate Mnemonics

As Boring,

Just Some Useless Nonsensical

Knowledge, But

Science

Out Changes

May View Established Models

As Basic

Justified Standards Until New

Knowledge Bears

Sometimes

Over Coals

My Very Energetic Mother

Also Boils

Jumbo Shrimp Using Nine

Kettles Bubbling

The Inevitable Question …

Why is Pluto No Longer a Planet?

Planet Pluto

January 23, 1930 January 29, 1930

Pluto/Charon

1978 – James Christy (USNO)

The Incredible Shrinking Planet

•  Lowell’s Planet X – 7 times Earth •  1940’s – 1 times Earth •  1980 – 0.1 times Earth •  1985 – 0.002 times Earth

Kuiper Belt Objects

•  1992 – Jewitt & Luu find QB1

•  Distance of 42 AU •  First (third?) object

discovered in the Kuiper Belt

Kuiper Belt

But Isn’t Pluto Special in Some Way?

Orbit Comparison: Pluto/Charon vs 2004 DW

Kuiper Belt

Moon

Eris & Dysnomia Haumea, Hi’iaka & Namaka

Makemake

KBO Size Comparison

Pluto vs the Kuiper Belt

•  Orbit similar to KBOs •  Size similar to KBOs •  KBO companions common •  Composition similar to KBOs

Pluto vs the Kuiper Belt

•  Orbit similar to KBOs •  Size similar to KBOs •  KBO companions common •  Composition similar to KBOs

Pluto has found its family!!

IAU Definition – August 2006 •  IAU defines “planet”

1.  Orbits the Sun 2.  Upper mass limit

•  not massive enough to produce fusion •  Deuterium fusion occurs at about 15x Jupiter’s mass

3.  Lower mass limit •  Massive enough for gravity to make it spherical •  About 500 miles in diameter

4.  Dominates its orbit •  Dwarf planets meet 1, 2, 3, but not 4

Other Planetary Systems?

•  Solar system alone is category of one

HR 8799

Planets around Other Stars

•  Jupiter mass planets in Mercury orbits •  Elliptical orbits •  Multiple Jupiter sized planets •  Planets around pulsars

Planetary System Formation

•  Planetary systems form in a predictable fashion from a spinning circular disk

Sun

Rocky Planets

Asteroid Belt

Giant Planets

Kuiper Belt

Oort Cloud

So Much to Discover

•  Our solar system is the oddball? •  Need to generalize our formation and

evolution scenarios •  Implications for life in the universe

– Lots of planets – Stability of orbits?

•  New era of solar system study

Presentation Materials

•  Online Sessions – Google Hangout September –  Info to come

•  Social media – Facebook.com/DrFrankSummers – Twitter @drfranksummers

http://tinyurl.com/PA-GSFC-2013