From Here to The Dawn of From Here to The Dawn of TimeTime

A. HerroldA. Herrold

To the edge of the solar system

• The orbit of Neptune is not at the edge of the solar system

• Past the planets is the Kuiper Belt, another large asteroid belt

• Next is the Oort Cloud

• The solar system ends at the heliopause

The Kuiper Belt• Asteroids from

Neptune to beyond Pluto

• Pluto is a KBO !• Tens of thousands

discovered• Home to short-

period comets

The Oort Cloud

• The home of a trillion long-period comets

• From 70 light-days to 3 light-years away

• Material in the Cloud = 40 X the mass of Earth

The Heliopause: The Heliopause: Where Sun meets StarsWhere Sun meets Stars

• The solar wind blows past the Oort Cloud.

• Other stars exert winds, too.

• The heliopause is where the edge of the Sun’s influence is felt.

The Nearest Stars to UsThe Nearest Stars to Us

The Milky WayThe Milky Way

The Galaxy in Infra-redThe Galaxy in Infra-red

The Galaxy as we know itThe Galaxy as we know it

The Orion ArmThe Orion Arm

The Galactic CenterThe Galactic Center

Dust and gas hide the view of the center of our galaxy in optical wavelengths.

The Galactic Center, Part 1The Galactic Center, Part 1

Two views of infrared:Right: a close-upBelow: a wide-angle view

The Galactic Center, Part 2The Galactic Center, Part 2

Left: X raysBelow: Radio waves

Black Hole at the Galactic Center –Black Hole at the Galactic Center –Swirling StarsSwirling Stars

Nearby GalaxiesNearby Galaxies

Spiral GalaxiesSpiral Galaxies

• Spirals have arms, a disk, a nuclear bulge and a halo.

• Young stars live in the disk and arms- old stars in the bulge and halo.

Barred Spiral GalaxiesBarred Spiral Galaxies

• Like spirals, except they have a star bar that runs through the nucleus

• Why?

Sideways SpiralsSideways Spirals• From the side,

dust lanes are often visible

• Old, metal-poor halo stars and globular clusters surround the galaxy

• Dwarf spirals also exist

Elliptical GalaxiesElliptical GalaxiesContain old stars and little dust

They are often found near the center of galaxy clusters

Perhaps they form as a result of mergers

Dwarf ellipticals often orbit larger galaxies

Astronomers often call this type “red and dead”

Irregular GalaxiesIrregular Galaxies

• These galaxies don’t fit into the other shapes and categories

• Their odd shapes may be due to interactions with other galaxies

• They are often small and may be the most common type

Galaxy InteractionsGalaxy Interactions

• Galaxies within a cluster often move towards or past one another

• This may result in mergers, cannibalism or perturbations

• Smaller “dwarf” galaxies often orbit larger ones

Galaxy MergersGalaxy Mergers

NGC 3521 shows tidal streams of materials fromone or more galaxies that merged with it

Andromeda Galaxy – Andromeda Galaxy – Spitzer Space TelescopeSpitzer Space Telescope

The Cannibalism of Centaurus AThe Cannibalism of Centaurus AThe small blue arc is a stream of stars 2000 light-years long. It is thought to be the remnants of a small galaxy that Centaurus A has “eaten”.

A3827 (below) shows the remains of 5 galaxies in its belly.

Et Tu, Brute?Et Tu, Brute?• Our own Galaxy is a cannibal. In the image below,

clouds of hydrogen and other elements are seen falling into or lurking around the Milky Way.

Galaxy Clusters- Galaxy Clusters- Abell 1185 and the GuitarAbell 1185 and the Guitar

The Hubble “Tuning Fork”The Hubble “Tuning Fork”

Hubble thought galaxy shapes may evolve as a function of their age.

Galaxy Types and Star FormationGalaxy Types and Star Formation

Instead, they may exhibit 2 different star formation behaviors, or be shaped based on their history of interactions.

The Local GroupThe Local Group

Our galaxy belongs to a cluster of more than 45 large and small galaxies.

The Great AttractorThe Great Attractor

Millions of galaxies stream toward a “mass” 250 miliion light years away simply known as “The Great Attractor”.

SuperclustersSuperclustersThe Shapley Supercluster is currently the largest known, having a diameter of more than 400 million light years.

The Great Wall of SloanThe Great Wall of Sloan

Superclusters seem to organize into “walls”, forming curved structures (bubbles) that seem to wrap around emptyareas (voids)in the universe.

Nearby NeighborhoodsNearby Neighborhoods

Edwin Hubble and his Edwin Hubble and his LawLaw

The farthest galaxies move the fastest

The slope of this line is the Hubble Constant

The Hubble Ultra Deep Field

Quasars:Quasi-Stellar Objects

Supernovas as “Standard Candles”

Supernovas as “Standard Candles”

By measuring the maximum magnitude of Type Ia supernovae, a distance can be determined.

(All Type Ia SN have a peak magnitude of -19.6)

Penzias and Wilson vs. the Pigeons

WMAP: the Wilkinson Microwave Anisotropy

Probe

The map produced by WMAP shows the universe as it existed only 380,000 years after the Big Bang.

The colors represent tiny temperature fluctuations.

The Early Universeaccording to WMAP