The Big Bang!The Big Bang!

Unit 1Unit 1

OriginsOrigins How and when did the:How and when did the:

universe form?universe form?

solar system / Earth form?solar system / Earth form?

Moon form?Moon form?

What were early Earth What were early Earth conditions?conditions?

How Do We Know?How Do We Know?

Origin of the UniverseOrigin of the Universe

Big BangBig Bang occurred 13.7 billion years agooccurred 13.7 billion years ago model for the beginning of the universemodel for the beginning of the universe

http://rainbow.ldeo.columbia.edu/courses/v1001/7.html

- infinitely dense point not governed by our physical laws or time

- all matter and energy contained in one point

Building a UniverseBuilding a Universe

http://rainbow.ldeo.columbia.edu/courses/v1001/7.html

- instantaneous filling of space with all matter

Building a UniverseBuilding a Universe

Edwin HubbleEdwin Hubble

Hubble’s Law States…Hubble’s Law States…

Universe is continuously expandingUniverse is continuously expanding

Galaxy’s velocity is proportional to its distance Galaxy’s velocity is proportional to its distance (galaxies that are twice as far from us move twice (galaxies that are twice as far from us move twice as fast)as fast) taken every galaxy the same amount of time to move

from a common starting position to its current position

Hubble’s EvidenceHubble’s Evidence

Doppler shifting - wavelength emitted by something moving away from us is shifted to a lower frequency

Sound of a fire truck siren - pitch of the siren is higher as the fire truck moves towards you, and lower as it moves away from you

Visible wavelengths emitted by objects moving away from us are shifted towards the red part of the visible spectrum

The faster they move away from us, the more they are redshifted. Thus, redshift is a reasonable way to measure the speed of an object (this, by the way, is the principal by which radar guns measure the speed of a car or baseball)

When we observe the redshift of galaxies outside our local group, every galaxy appears to be moving away from us - universe is expanding.

Evidence for Big BangEvidence for Big Bang

Red shift - as light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to wavelengths being stretched

In 1964, Arno Penzias and Robert Wilson, discovered a noise of extraterrestrial origin that came from all directions at once - radiation left over from the Big Bang

In June 1995, scientists detected primordial helium in the far reaches of the universe - consistent with an important aspect of the Big Bang theory that a mixture of hydrogen and helium was created at the beginning of the universe

When Did the Universe Form?When Did the Universe Form? 10 to 20 billion years ago 10 to 20 billion years ago

(13) (13)

How do we know? How do we know? spreading (Red Shift)spreading (Red Shift) know distances, rates of know distances, rates of

retreat, relative retreat, relative positions positions

afterglow of the Big afterglow of the Big BangBang

Orion Nebula - http://stardate.utexas.edu/resources/ssguide/planet_form.html

Features of Our Solar Features of Our Solar SystemSystem

Sun 8 planets 101 known moons (satellites) a tremendous number of asteroids

most orbit the Sun between the orbits of Mars and Jupiter

millions of comets and meteorites interplanetary dust and gases

Relative Sizes of the Relative Sizes of the Sun and PlanetsSun and Planets

Solar System Solar System ConfigurationConfiguration

Origin of Our Solar SystemOrigin of Our Solar System

Solar nebula theorySolar nebula theory

formed a formed a rotating diskrotating disk

condensed and condensed and collapsed due collapsed due to gravityto gravity

forming forming solar nebulasolar nebula with an embryonic Sun with an embryonic Sun surrounded by a rotating surrounded by a rotating

cloudcloud

cloud of gases and cloud of gases and dustdust

The PlanetsThe Planets

Terrestrial Terrestrial PlanetsPlanets Mercury Mercury VenusVenus EarthEarth Mars Mars

small, composed small, composed of rock, with of rock, with metal coresmetal cores

Jovian PlanetsJovian Planets Jupiter Jupiter SaturnSaturn UranusUranus NeptuneNeptune

large, large, composed of composed of hydrogen, hydrogen, helium, helium, ammonia, ammonia, methane, methane, relatively small relatively small rocky coresrocky cores

– Pluto?

PlutoPluto Not classified as a Terrestrial planet Not classified as a Terrestrial planet

because of its low density and small because of its low density and small sizesize

Not classified as a Jovian planet due to Not classified as a Jovian planet due to its solid surfaceits solid surface

Atmosphere composed of unknown Atmosphere composed of unknown quantities of methane and nitrogenquantities of methane and nitrogen