3 Pluto Not a Planet What's Going on in the Universe

8/11/2019 3 Pluto Not a Planet What's Going on in the Universe

1/48

1

Whats going on in the Universe?

Jocelyn Bell Burnell

University of Oxford Astrophysics

&

Mansfield College


2/48

2

Contents

Plutoan update

Dark matter

Dark energy


3/48

3

Pluto


4/48

4

Old solar system


5/48

5

Pluto and the Lowell Observatory

Pluto discovered in Feb 1930

announcement held until 13thMarch, the

75thanniversary of Percival Lowells birth.

Initially believed to be much more massive

than it actually is.

Not yet named.


6/48

6

Oxford school-girl names Pluto!

14/3/1930; newspapers carry

news of discovery

Venetia Burneys grandfatherreads out to her The Times

report. Grandfather is the

retired Librarian of Oxford

Universitys BodleianLibrary.

Venetia suggests Pluto Venetia Burney Phair


7/48

7

Name forwarded

Grandfather impressedtakessuggestion to Herbert HallTurnerOxfords SavillianProfessor of Astronomy

15thMarch HHT telegraphsname to Lowell Observatory

Observatory likes name andadopts it.

Herbert Hall Turner


8/48

8

Problem with Pluto 1

Unusual orbithighly inclined to plane (satah) where allthe other planets orbit. Also more eccentric (although not

by a lot)

Diagrams compare orbits of Pluto and Neptune.


9/48

Plutos orbit

9


10/48

10

The problem with Pluto 2

Smallest mass planet (one-thirtieth of mass ofMercury); for many years its mass and diameterwere overestimated.

Smaller and less massive mass than some moons(7moons) Ganymede (Jupiter), Titan (Saturn),Callisto (Jupiter), Io (Jupiter), the Moon, Europa(Jupiter), and Triton (Neptune).

(Pluto on bottom right!)


11/48

11


Charonbig for a moon

when compared with

Pluto. Unusualboth tidally

locked (each always

shows the same face to

the other)


12/48

12


Pluto has pals! Lots of

Pluto-like things are

being discovered a bitfurther out than Pluto.


13/48

13

More to come!

Half a million Kuiper belt objects

with diameters greater than 30kilometers.

Beyond Neptune there are estimated

to be more than 100000 icy objectswith diameters over 100km.

Are rich in ices & have similarphysical properties of comets

With new telescopes (e.g PanStarrs)coming on line more and more ofthese will be discovered.

Kuiper belt,

at ~ 30100

AU from the

sun.

Second

source of

small, dark,icy bodies in

the outer solar

system beyond

Neptune

discovered

since 1992

Origin of short

period comet

(< 200 years)


14/48

14

Kuiper Belt and Oort Cloud

Kuiper Beltouter part ofsolar system; source ofmost of these objects

Oort Cloudspherical cloudenveloping solar system;(named after Dutch astronomerJan Oort) source of many

comets. Sedna comes from OortCloud. (origin of long-periodcomets (10,000 X Earth-Sundistances)


15/48

15

Pan-Starrs

4 x 1.8 m telescopes

Located in Hawaii

Primary task toidentify hazardous

asteroids


16/48

16

Definition of a planet

A planet could be defined in several ways:

it orbits the Sun (but is not a moon, an

artificial satellite, or another star) it is round(-ish)

it was formed from the proto-solar disk

it is the dominant object/has cleared its orbit it causes perturbations of other planets

motion


17/48

17

International Astronomical Union

The world body responsible for definitions

and for naming objects

About 2000 astronomers in membership

Meets every three years for 10 days

summer 2006 in Prague. In 2009 in Rio de

Janiero. (Executive Committee meets moreoften.) Resolutions Committee.


18/48

18

Todays Definitions

A PLANET

Orbits Sun, is not a satellite, nor a star

Round (ish)

Has cleared its orbit

A DWARF PLANET

Orbits Sun, etc Is round(ish)

SMALL SOLAR SYSTEM BODIES


19/48

19

Issues outstanding

Boundary between brown dwarf (failed star)

and large planet.

Relation to planets around other stars.

Definition of binary planets/dwarf planets

(e.g.Pluto and Charon)

Naming issues


20/48

20

The Milky Wayour galaxy


21/48

21

Rotating, spiral galaxy


22/48

22

Andromeda Galaxy


23/48

23

Our Galaxythe Milky Way

Our Sun is one of 100 thousand millionstars that make up the Milky Way.

It is an average star, located two-thirds ofthe way out from the centre.

Galaxy is disk-shaped, 100,000 light yearsdiameter.

Sun rotates round centre of galaxy at ~ 200km/s


24/48

24

Orion and Milky Way


25/48

25

Milky Way + telescope


26/48

26

The Milky Way in other languages

Australian AboriginalThe RainbowSerpent

CelticThe Silver Street (Arianrod) ChinaThe Celestial River

Cree IndianThe Path of the Spirits

Ancient HebrewRiver of Fire

KalahariThe Backbone of the Night


27/48

The Milky Way in other languages,

contd KoreanSilver River Water

Maori - The Long Fish

SetswanaThe Place where the LighteningRests

SiberiaSilicon River

SwedenThe Winter Road

27


28/48

28

Dark matter and the rotation of galaxies


29/48

29

Spiral galaxies


30/48

30

Wheres the edge of the galaxy?

As the edge of the visible galaxy is reached you wouldexpect this rotation curve to start dropping it shouldfollow Keplers Third Law.

It doesnt! Besides the visible material there must be darkmaterial which contributes gravity


31/48

31

Clusters of galaxies

and dark matter


32/48

32

Perseus Cluster of Galaxies

Galaxies moving so

fast the cluster should

break up. We see no sign of

clusters breaking up.

Does extra, dark

material in cluster

provides gravity to

bind cluster?


33/48

Lensed image of object behind

cluster

33


34/48

34

Dark matter

To prevent galaxies and clusters of galaxiescentrifuging apart we postulate the

existence of dark matter. This material has gravity, but does not

shine.

There may be several kinds of dark matter.

All of them must be totally different fromthe material know about already.


35/48

35

The history of the universe


36/48

36

The Beginning of the Universe

The Universe began 13.7 billion years ago with a

BIG BANG

All the universe, all of space, matter, energy, timestarted with a huge explosion from a tiny size.


37/48

37

Evidence for Big Bang

Galaxies moving apart; they appear to have

been all together at one point in past.

Cosmic microwave background radiationleft over from Big Bang; now cooled to

about 3K. (2006 Nobel prize for physics.)

The abundance of deuterium


38/48

38

The Evolution of the Universe


39/48

39

Dark energy accelerating the expansion of

the universe


40/48

40

An accelerating phase?


41/48

41

An accelerating universe

Something is causing the expansion of the

Universe to accelerate.

We dont know what it is, but we feel betterif we give it a namedark energy.

The acceleration shows in the Universe

today, but was not noticeable in the earlieruniverse.


42/48

42

The Content of the Universe

Of the mass-energy

that makes up our

Universe: 4% is ordinary matter

(the stuff we and our

world are made out of)

23% is dark matter

73% is dark energy


43/48

43

In conclusion

We have had to invent dark matter to stop

galaxies and clusters of galaxies from flying

apart. We have had to invent dark energy to

explain why the expansion of the universe is

getting faster not slower.


44/48


45/48

45

Our Galaxythe Milky Way

Our Sun is one of 100 thousand million stars that

make up the Milky Way.

It is an average star, located two-thirds of the wayout from the centre.

Galaxy is disk-shaped, 100,000 light years

diameter.

Sun rotates round centre of galaxy at ~ 200 km/s

Monty PythonGalaxy Song


46/48

46

Carl Sandburg

USA poet, Pullitzer prize winner. 18781967

Remember who you are. Remember you areone of the latest products of millions ofyears of toil and play and regurgitation ofuniversal forces. The rain and stars and dust

of a thousand worlds that have perishedhave contributed to the making of you.

Part of A L ittl e Sermon, 1907.


47/48

47

Kuiper Belt and Oort Cloud

Kuiper Beltouterpart of solar system;source of most of

these objects Oort Cloudspherical

cloud enveloping solarsystem; source of

many comets. Sednacomes from OortCloud.


48/48

48

We are exceptional!

Live in an exceptionally dense part of theUniverse

Live in a chemically a typical part of theUniverse

We are made of matter, not antimatterweowe our existence to a ninth decimal place

anomaly! We are made of baryons, particles which make

up only 4% of the mass-energy of the universe.

Documents

3 Pluto Not a Planet What's Going on in the Universe