Physical Science
Universe
Slides subject to change
Job 38
14 Where were you when I laid the Earth’s
foundation?
31
Can you bind the beautiful Pleiades?
Can you loose the cords of Orion?
32 Can you bring forth the constellations in
their seasons
or lead out the Bear with its cubs?
2
Celestial Sphere
North Celestial Pole
North Pole
Celestial Equator
Equator
South Pole
South Celestial Pole
The Sun: Our Nearest Star
4
Sun
Diameter: 109 Earths
 Mass: 333,000 Earths
 Density: Avg. 1.4 g/cm3
 Sun exists as a plasma, and
is not solid.
 Gravity: 27.9 g


Solar Day: 25 days
5

Solar and Heliospheric Observatory

ESA/NASA Collaboration
6
Sun
Nuclear reaction at Core
 Bright visible surface
“Photosphere”
 Thin layer of hotter gas
“Chromosphere”
 White halo “Corona”


Temperature
15,000,000 K
6,000 K
50,000 K
1,000,000 K
Sun is hotter as you rise
above the surface.
7
Sun's Power
Nuclear fusion of hydrogen into helium in
its core.
 Normally (at Earth temperatures)
hydrogen nuclei (protons) repel each
other.
 At Sun's core, T =15,000,000 K, protons
collide with such energy they fuse.
 Energy released as hydrogen goes
through several steps to become stable
helium.

8
Nuclear Fusion

Every second in the sun’s interior mass is
converted to energy:

hydrogen (H) → helium (He) + energy

6.0x1011 kg H → 5.96x1011 kg He + energy

Enough fuel to last another five billion
years.
9
Solar Flares
Charged particles in the midst of intense magnetic fields.
Photo March 18, 2013 by NASA Solar Dynamics Observatory
10
Sunspots

Cooler areas on the sun (T ≈ 4600 K).
NASA
11
Sunspots



Sunspot intensity cycles every 10-11 years.
Emitted radiant energy varies with sunspot activity.
Significant influence on Earth’s climate.
12
Effect of Sunspots
Red curve illustrates
solar activity.
 Black curve, Earth's
average temperature.
 Over last 100 years,
average global
temperature has increased by approx 0.7 °C.

Earth’s climate is closely associated with Solar
activity – correlates with colder temperatures.
Science, 254, 698-700, 1991
13
2009 had 260 spotless
days
2010 had 51 spotless days,
2011 had 2 spotless days
Since then there have
been sunspots every day.
www.almanac.com/sunspotupdate
Today’s Activity
14
Climate Change
15
Stars
Like the Sun, other stars are massive,
luminous balls of plasma.
 Most stars between 0.1 and 5 solar masses.
 Size is a balance of thermal and radiant
pressure outward, and gravity inward.
 Once regarded by astronomers as a small
and relatively insignificant star, our Sun is
now thought to be brighter than about 85%
of the stars in the Milky Way galaxy.

16
Measure Star Brightness
 More
negative the number, the more bright !
 Apparent magnitude of the Sun is −26.74,
and the mean apparent magnitude of the full
moon is −12.74. The Sun is the brighter of
the two objects.
 The apparent magnitude of Sirius is −1.44,
and the apparent magnitude of Polaris is
1.97. Sirius is the brighter of the two stars.
 Hubble Space Telescope can see stars of
magnitude 30.
17
Star Magnitude Scale
Sky Map
18
Star Distances





1 light year—the distance light goes in
one year—approx. six trillion miles.
1 light year = 9.46x1015 meters.
Closest star to us: Proxima Centauri
(4.3 light years).
Keep in mind it only takes 8 minutes for
light to come from the Sun to Earth.
About 17 hours from Earth to Voyager 1
(125 AU from Sun)
19
View of Stars
Long photo exposure
of stars from Oregon.
 Center of concentric
circles is Polaris, the
“North Star” at the
North Celestial Pole.
 Polaris is 431 light
years from Earth.

20
Big
Dipper
East
Venus
Jupitor
Uranus
West
Orion
5:00 am 9/22/12
21
Big
Dipper
East
Venus
Jupitor
Uranus
West
Orion
6:00 am 9/22/12
22
Big
Dipper
East
Sun
Uranus
Venus
West
Jupitor
Orion
7:00 am 9/22/12
23
Ursa Major
Ursa Minor
The Little Bear
Ursa Major
The Great Bear
24
Big Dipper

The Big Dipper is formed
by seven major stars
within Ursa Major.

In the U.S. this group of seven stars is called
the “Big Dipper.” UK and Ireland, the
“Plough.” American Indians referred to it as a
bear and three cubs.

In 19th century, runaway slaves would follow the
“drinking gourd” to head north and freedom.
25
Where is Polaris in the Sky?
Find the Big Dipper
within Ursa Major.
 Two end stars point
to Polaris,
approximately seven
lengths.


Polaris is in the
handle of Little
Dipper (Ursa Minor).
26
Sirius

Brightest star in the sky, magnitude −1.4.
Known as the "Dog
Star", in its constellation,
Canis Major (Big Dog).
Faithful dog of Orion the
Hunter.
 Bright because it is relatively close, 8.6
lightyears, and hot (10,000 K vs Sun 6,000 K).
 Find it by following the “belt of Orion”
southward.

27
Betelgeuse
Betelgeuse (“beetlejooz”) is a red supergiant
star approaching end of
its life cycle.
 Ninth brightest, reddish
tinge.
 641 light years away.
 Located in constellation
Orion. Near the belt.
 If put in place of our Sun,
would reach to Jupiter.

Hubble telescope, Visible
28
End of a Star’s Life
The future of Betelgeuse—In larger stars,
nuclear fusion continues until the heavier
core has grown so large that it can no
longer support its own mass.
 This core will suddenly collapse.
 The shockwave formed by this sudden
collapse causes the rest of the star to
explode in a supernova.
 Most of the matter in the star is blown
away by the supernova explosion

29
Nebulae




Crab Nebula first observed
1731.
Corresponds to bright (6x
Venus) supernova recorded
by Chinese and Arab
astronomers in AD 1054.
At center is the Crab
Pulsar, a rotating neutron
star roughly 20 km in
diameter. ρ=1014 g/cm3
Pulsar blinks light, 30 times
per second.
Crab Nebula 6,300 ly – Hubble
30
Edwin Hubble
 Up to the early 1900’s the Milky
Way was considered the
universe.
 Edwin Hubble collected data from Mt.
Wilson Observatory, and announced in
1925 that there were other galaxies
beyond the Milky Way (in particular the
Andromeda Galaxy)
 His announcement changed our view of
the universe.
Mt Wilson Webcam
31
Andromeda Spiral Galaxy Amateur Telescope
32
Andromeda Galaxy
Andromeda Spiral Galaxy Hubble
33
Nearest Galaxy to Milky Way
 The Hubble Space Telescope is named in honor of Edwin Hubble.
34
Galaxies
A galaxy is a massive system consisting of
stars, gas and dust, and “dark matter.”
 Range from ten million to one trillion stars,
average 100 billion.
 Stars orbit a common center of mass.
 Our Sun is one of the stars in the Milky
Way galaxy.
 Classified according to their shape,
elliptical, spiral, starburst, ...

35
Milky Way Galaxy

Milky Way spiral galaxy.

Sun is on the “Orion”
arm.

100,000 ly in diameter.

200 billion stars.

One of a cluster of 40
galaxies called the
Local Group. Includes
Andromeda Galaxy.

Artist concept→
Artist concept36
M104 Sombrero Galaxy
37Hubble , Visible
Nearby Spiral Messier 81 Galaxy,
12 million light-years - NASA Spitzer
38
Space Telescope, Infrared
A Full Ring Galaxy - NASA Hubble
39
Black Hole
A Black Hole is at the center of each
galaxy, and its size correlates to the size
of each galaxy.
 A black hole is a place in space where the
gravity is so strong that nothing—not even
light—can escape it.

This is not a
This is a Black Hole
black hole.
40
Observable Universe
100 billion galaxies in the observable
universe.
 Approximately 100 billion stars in each
galaxy.
 Galaxies range from 3 to 300,000 light
years in diameter.
 “Dark matter” is an invention to explain
why galaxies rotate as if they are much
heavier than they appear. Unseen mass.
Galaxy may be up to 90% dark matter.

41


Dark lines from
absorption of specific
light colors by the gases
in the Sun’s
photosphere.
H and He.
 Doppler effect
Lower Frequencies
Red Shift
 Light from stars
moving away
from Earth
 Stellar Doppler effect
42
Universe Is Expanding
Hubble’s Law (1929):
“The redshift in light coming from
distant galaxies is proportional to
their distance.”
 Formulated in 1929 based on Hubble’s
additional measurements from Mt. Wilson.
 Most cited evidence for the “Big Bang”
model of the universe.
 Sometimes the energy for this expansion
is called “dark energy.” Not understood.
43
Big Bang
Cosmological model of the universe
 Supported by all lines of scientific
evidence and observation.
 Essential idea is that the universe has
expanded from a primordial hot and dense
initial condition at some finite time in the
past and continues to expand.
 Extrapolation of the expansion of the
universe backwards in time helps fix a
date ~ 13 billion years ago.

44
Mote of Dust
1990 Voyager
photo taken as
Voyager exits
Solar System.
 Earth is 4 billion
miles away.

45

Compare Carl Sagan’s view of Earth
http://obs.nineplanets.org/psc/pbd.html

With God’s:
Isaiah 45:18 “For this is what the LORD
says— he who created the heavens, he
is God; he who fashioned and made the
earth, he founded it; he did not create it
to be empty, but formed it to be
inhabited.”
Romans 5:8 But God demonstrates his
own love for us in this: While we were
still sinners, Christ died for us.


Earth and Moon
seen from Mars by
MGS on 8 May
2003
46