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From Here to The Dawn of Time A. 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.
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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
TheKuiper 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: Where 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 Galactic Center Dust and gas hide the view of the center of our galaxy in optical wavelengths.
The Galactic Center, Part 1 Two views of infrared: Right: a close-up Below: a wide-angle view
The Galactic Center, Part 2 Left: X rays Below: Radio waves
Spiral 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 Galaxies • Like spirals, except they have a star bar that runs through the nucleus • Why?
Sideways 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 Galaxies Contain 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 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 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 Mergers NGC 3521 shows tidal streams of materials fromone or more galaxies that merged with it
The Cannibalism of Centaurus A The 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? • 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.
The Hubble “Tuning Fork” Hubble thought galaxy shapes may evolve as a function of their age.
Galaxy Types and Star Formation Instead, they may exhibit 2 different star formation behaviors, or be shaped based on their history of interactions.
The Local Group Our galaxy belongs to a cluster of more than 45 large and small galaxies.
The Great Attractor Millions of galaxies stream toward a “mass” 250 miliion light years away simply known as “The Great Attractor”.
Superclusters The Shapley Supercluster is currently the largest known, having a diameter of more than 400 million light years.
The Great Wall of Sloan Superclusters seem to organize into “walls”, forming curved structures (bubbles) that seem to wrap around empty areas (voids) in the universe.
Edwin Hubble and his Law The farthest galaxies move the fastest The slope of this line is the Hubble Constant
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)
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.
