The Solar System, stars, the Universe

1
The Solar System, stars, the Universeand you

• Setting a context for us in the Universe
• The solar system
• Other stars
• Our Milky Way Galaxy
• Other galaxies
• The Big Bang
• The enormity of timelines
• Take home message a good idea of our place in
  space, and how the building blocks of life came
  to be.

2
The Solar System

• All the objects within the Suns zone of
  gravitational influence.
• The Sun
• 99 of the solar system mass
• 110 Earths diameter
• 4.5 billion years old (10 billion year life
  expectancy)
• An unremarkable star.

3
Tiny Terrestrial Planets
Mercury hot, airless Venus hot, thick
atmosphere Earth moderate atmosphere,
warm. Moon no atmosphere, chillier. Mars
tiny atmosphere, chilly indeed.
4
Giant Jovian Planets

• Jupiter enormous, about 1 stellar mass.
• Saturn very large, spectacular rings.
• Uranus cold, relatively quiet tilted sideways.
• Neptune strangely turbulent.

5
Solar System Detritus

• Interplanetary dust
• Asteroids
• Asteroid belt (2.1-3.3 au)
• 1-2106 objects 4 Moons mass. (CONFUSED BY
  SCIENTIFIC NOTATION? Read Appendix C)
• Kuiper belt
• 30-50 au
• 105 cometary objects
• Largest known is Eris (2500 km diameter).
• Comets
• Periodic (i.e., Tempel, 5.5y orbit)
• Öort cloud (50,000 au)
• 1012 cometary objects.

6
The Solar Systemdistance scale
(set 1 au15m, 50 ft)

• Sun diameter17 cm (6.6 inches)
• Earth diameter 2 mm (1/16 inches)
• 15 m from Sun
• Jupiter diameter 1.4 cm (1/2 inch)
• 80 m from Sun

7
The Sun and Jupiter
8
The Solar System distance scale
(set 1 au15m, 50 ft)

• Neptune diameter 0.5 cm (1/5 inch) 450 m
  from Sun (1/4 mile)
• Kuiper belt 450-750 m from Sun (1/4 1/2 miles)

9
Sun, Neptune, Kuiper Belt
10
The Solar System distance scale
(set 1 au15m, 50 ft)

• Öort cloud 750 km (470 miles)
• (Sierra College to San Diego)
• Nearest star 4000 km (2500 miles)
• (Sierra College to New York City)

11
Stars

• Our Sun is a relatively common type

12

• Stars
• Each different kind has a different life history

The bigger stars have more raw fuel but, they
use it faster ? Big stars burn out quickly
The smallest stars have very little raw
fuel but, they use it sparingly ? Tiny stars
live very, very long times
13
Stars and nucleosynthesis

• Stars turn hydrogen into helium via nuclear
  fusion
• Stars also fuse helium into carbon, and the most
  massive engage in even more complicated atomic
  fusion reactions that produce other atoms such as
  phosphorus, nitrogen, etc.
• Carbon stars are giants that lose up to half
  their mass via huge winds that blow off their
  surfaces.

14
Supernovae friends and foes

• Produce atoms more massive than iron.
• Cause ionizing events there is no defense!

15
The Milky Way Galaxy

• A massive grouping of stars, dust, and gas, and
  related phenomena.
• Dimensions
• Disk 100,000 LY across 1000 LY thick
• We are 28,000 LY from center
• 100 billion times mass of Sun (interior to
  Rsun).

16

• Galactic recycling (star-gas-star cycle)

• Interstellar medium (ISM) is mostly H, He
• Star formation occurs
• Stars produce winds which fertilize the ISM
• Stars supernovae, further fertilizing the ISM.

17
Types of galaxies

1. Spirals
2. Ellipticals
3. Irregulars

18
Galactic evolution

• All galaxies seem likely to harbor supermassive
  black holes106 - 108 the mass of the Sun.
• Central black holes calm down in time
• Galaxies collide with each other
• Galaxies consume their interstellar matter

19
Galaxy groups

• Galaxies occur in clusters
• Clusters occur in superclusters
• Nearest large galaxy (Andromeda galaxy) is 2.5
  MLY away.
• Superclusters are about 100 MLY across.

20
Receding galaxies

• Redshift studies have revealed that nearly all
  galaxies are rushing away from us.
• The farther a galaxy is from us, the faster it is
  rushing away.
• Truly distant galaxies are rushing away from us
  at speeds approaching the speed of light!
• What is the matter with us?

21
The Big Bang

• Galaxies are receding from us because space is
  expanding.
• This is NOT a cosmic explosion in space. It is a
  cosmic explosion OF space.
• All points in the Universe see galaxies receding
  from them.
• This was the first hint of the Universes
  history, treated by the Big Bang Theory!

22
Consequences of the Big Bang theory

• The Universe
• enlarged and cooled with time
• started out as pure H and He.
• continues to age
• The Big Bang theory accurately explains the
  relative H and He concentrations in the Universe,
  its clumpiness, age, background radiation, and
  other things.
• Dark Matter and Dark Energy are recent
  discoveries needed to explain some observations.
• See Astro 5 or (especially) Astro 25 for
  details!

23
The Enormity of Timelines

• Age of Universe
• 13.5-14 billion years
• Age of Milky Way Galaxy
• at least 13.2 billion years
• Age of Sun
• 4.6 billion years
• Age of Earth
• 4.5 billion years
• First life on Earth
• 3.7 billion years
• Homo sapiens
• 200,000 years (0.0014 of Universes age)