UNIT 1 DYNAMIC EARTH AND BEYOND Beyond Earth
UNIT 1 DYNAMIC EARTH AND BEYOND Beyond Earth Tools of Astronomy Science of the Earth o. Electromagnetic Parts of Earth Science Radiation o 4 Major Areas o. Satellites & Telescopes o 4 Major Systems Moon Dynamic Earth o. Creation, Features, & o. Tornados, Tsunamis, & Phases Earthquakes o. The Space Race o. Exacerbation and Mitigation Synergy of the Sun-Earth. Moon o. Solstices and Equinoxes o. Influences and Effects Our Galaxy o. Type o. Location Within Our Solar System o. Terrestrial Planets Unit I: DYNAMIC EARTH AND BEYOND o. Gas Giants
BEYOND EARTH Our Galaxy OUR GALAXY – Where we are in the MILKY WAY Formation and Evolution of the Milky Way The halo and bulge are exclusively made up of old stars suggesting these formed first • Astronomers hypothesize that the galaxy began as a spherical cloud • The cloud eventually collapsed under the force of its own gravity • Rotation therefore gave it its disc like shape Stars forming afterward have orbits lying on the plane of the disc • Greater quantities of heavier elements • Formed by gasses enriched from previous generations of stars Spiral arms are thought to be under constant development and evolution Unit I: DYNAMIC EARTH AND BEYOND
BEYOND EARTH Our Galaxy OUR GALAXY – Where we are in the MILKY WAY Our viewing perspective • Appears as a band of stars stretching across the sky • We are part of that band • The real view is one of a disc’s edge From our perspective, a hazy band of light across the sky • Not something we are looking at • Something we are looking outward What we do not know • How large the galaxy is from • Where the center is • We are within it and in fact, we are a • Where we actually are in it very small part To really see, we must be away from the lights of civilization and the Moon Our Sun is one of 100, 000, 000 or so stars within this galaxy Unit I: DYNAMIC EARTH AND BEYOND
BEYOND EARTH Our Galaxy OUR GALAXY – Where we are in the MILKY WAY Suggested that the Milky Way Galaxy has some interesting features Spiral Arms – Speculation on the part of Astronomers that our galaxy, like many Mapping of the Milky Way Galaxy is largely others, also contains spiral arms. Hydrogen through radio waves mapping is again the source. • Radio waves can penetrate • Supposedly we have four major spiral interstellar gas and dust without arms scatter or absorption • Numerous minor spiral arms • There is also a measure of infrared radiation The Sun is in the minor arm Orion • Orbital speed is 220 Km/sec Found the center, the “Galactic Center” to • Orbital period is 240 million years be surrounded by a nuclear bulge • Has orbited the galaxy approximately • Sticks out of the galactic disc 20 times like a yolk in an egg • Around the bulge and the disc are a halo • Spherical region • Globular clusters present Unit I: DYNAMIC EARTH AND BEYOND
BEYOND EARTH Our Galaxy OUR GALAXY – Where we are in the MILKY WAY Mass About 100 Billion times that of our Solar System Astronomers have found significantly more mass towards the disc’s outer area • Indication the mass is more outward than at the center (90% is in the halo) • Part of the mass includes burnt out stars (e. g. , white dwarfs) Galactic Black Hole • Near the center, Sagittarius, is an area smaller than our solar system • 2. 6 million times the mass of the Sun Unit I: DYNAMIC EARTH AND BEYOND Stars Within The halo of the Milky Way contains the oldest known objects • Globular clusters, estimated to be 12 to 14 billion years old • Have traces of elements heavier than hydrogen an indication of their extreme age Younger stars are in the spiral arms • Here there is a concentration of gasses and dust • Star formation occurs here Population I Stars: Those in the disc and arms with heavy elements Population II Stars: Those in the halo and bulge with only traces of heavy elements
BEYOND EARTH Solar System OUR SOLAR SYSTEM – Terrestrials and Gas Giants • Also called rocky or telluric planets Terrestrial Planets • Mostly rock and heavy metals Mercury • These have a core made of heavy Venus metals Earth • Mostly iron Mars • Surrounded by a mantle of silicate rock The Gas Giants • Much smaller than gas giants Jupiter • Varied terrain Saturn • Volcanoes Uranus • Canyons, Neptune • Mountains • Craters The Asteroid Belt • Few or no moons Located between • No planetary rings Mars and Jupiter • Atmospheres vary • Asteroids/Minor/D • Venus’ thick CO 2 warf • Almost nothing on Mercury • Some small as a dust particle Unit I: DYNAMIC EARTH AND BEYOND • Almost entirely formed of various gases with a rocky center • Layers of hydrogen and helium molecules • Rocky center is actually molten “heavy metals” • These have numerous similar characteristics • All are outer planets (furthest from the Sun) • Massive • Low density • Fast rotations • Extreme cold • Numerous satellites (moons) • Ring systems • Astronomers have found gas giants in other solar systems • Extra-solar planets • Some in the habitable zones of other solar systems
- Slides: 6