Origin of star planets and life

The Origin of Stars, Planets, and Life in the Universe

Dr. Natalie Batalhanbatalha@science.sjsu.edu

How many planets are there in our Solar System?

Poll Question:

Taking an Inventory of the Solar System

PlutoNeptune Comet

UranusMarsEarth

Saturn

Mercury

Sun

Venus

Jupiter

http://www.cfa.harvard.edu/iau/lists/InnerPlot.html

Solar System Table of Contents:

I. SunII. Mercury, Venus, Earth, MarsIII. Asteroid BeltIV.Jupiter, Saturn, Uranus, NeptuneV. Kuiper Belt (icy asteroids)VI.Oort Cloud (comets)

SIZE SHAPE ORBIT TEMP COMP

Which of the following criteria are important for defining a planet?

Size and Shape: Earth is spherical, asteroid Gaspra is not.

12,800 kilometers(avout 8000 miles)

15 kilometers(about 9 miles)

Asteroid Ceres is spherical and about the size of Texas. Is it a planet?

Io Europa Ganymede Callisto

MoonMercury

MarsPluto

Definition so far:a) Orbits the Sun;b) Is at least as large as Pluto.

Ceres GanymedeYES NO YES NO

Orbital Characteristics

Mercury Earth Mars

7° Venus

SaturnJupiter

Uranus

Neptune

Pluto

17°

Poll Question:

Why is Pluto’s orbit different from those of the other 8 planets?

Discovery of Kuiper Belt Objects

• 1992, Jane Luu and David Jewitt

• More than 1,000 KBO’s now known

• 11 Pluto-sized KBO’s

• Pluto is a Kuiper Belt Object

How to Find Kuiper Belt Objects

The Orbits of Some Kuiper Belt Objects

Artist’s Depiction of UB313

Credit: Robert Hurt (IPAC)

UB313(1500 miles)

Should UB313 be the 10th Planet in the Solar System?

Yes No

Size Orbit History Population

Which of the following criteria are important for defining a planet?

193 planets orbiting other stars (a total of 155 systems) have been identified to date.

What do they tell us?

Most are in elliptical orbits

Gas giants are seen orbiting very close to their parent star!

Copyright © 1998-2006 Lynette R. Cook

Three planets all within 0.2 AU (Mercury orbits at 0.4 AU!)

Giant planets with 10x’s the mass of Jupiter.

Copyright © 1998-2006 Lynette R. Cook, All Rights Reserved

The International Astronomical Union is

working to craft a definition that satisfies both Solar System and Extra-Solar

System findings.

Summary

• Object size and orbit main criteria

• Historical context a consideration (Pluto is already on all of the plastic placemats!)

• Membership in a larger population will also be a consideration

• Object must be smaller than about 13 x’s Jupiter’s mass

For more information:

Discovery of UB 313:http://www.gps.caltech.edu/~mbrown/

First Discovery of Kuiper Belt Objects:http://www.ifa.hawaii.edu/faculty/jewitt/kb.html

List of planets orbiting other stars:http://exoplanet.eu