Basics of the Universe

Astronomy Cosmology the study of the universe the branch of astronomy that deals with the origin, large-scale properties, and the evolution of the observable universe

The Universe sum total of all things which can be directly observed or whose physical effects on other things can be detected in simpler terms, space and all the matter and energy in it major components: galaxies solar systems planets

Early History of the Universe Matter as we know it did not exist at the time of the Big Bang, only pure energy. Within one second, the 4 fundamental forces were separated gravity - the attraction of one body toward another electromagnetic force - binds atoms into molecules, can be transmitted by photons strong nuclear force - binds protons and neutrons together in the nucleus weak nuclear force - breaks down an atom’s nucleus, producing radioactive decay

Early History of the Universe After 3 minutes, photons and neutrons began to fuse to form the nuclei of hydrogen and helium atoms About 300,000 years later, temperatures were cool enough for complete hydrogen and helium atoms to form Photons escaped from matter about the same time, and light existed for the first time

Changing Composition of the Universe 200 million years later, with expansion still occurring, stars and galaxies began forming from leftover matter - hydrogen and helium nuclear fusion in stars has reduced the original composition of 100% H and He to 98% when a dying star explodes, the heavier elements created by fusion are blown into space to be recycled by newly forming stars the overall composition of the galaxies is gradually changing to the heavier elements

Why the Speed of Light is a Speed Limit Energy of a Moving Object in Relativity: E = mc2 One consequence: as v approaches c, Energy goes to infinity Also, as we approach c, Energy goes up very fast

Fuel Economy of a Starship At 0.1 c, energy is 0.7% greater than Newtonian formula At 0.5 c, 24% greater At 0.9 c, 3 x greater At 0.99 c, 12 x greater At 0.999 c, 43 x greater Each extra 9 more than triples the energy Getting our 1000 ton ship to 0.9 c takes 1.1 x 1023 joules = U.S. energy use for 1100 years

Astronomical Unit (AU) unit of distance equal to the average spacing between the Earth and the Sun equal to about 150 million kilometers (93 million miles) light takes about eight minutes to cover this distance The Earth animation is not rotating in the correct direction; it should be rotating from west to east 150 million km (93 million mi.)

Light Year the distance that light travels in one year in a vacuum, which is about 9.5 trillion kilometers (6 trillion miles) The Milky Way Galaxy is about 100,000 light years in diameter the speed at which light travels this distance is about 300,000 km/sec (186,000 mi/sec) The second closest star to the Earth is a little over four light years away. How far away (in miles) is the star?

If one parsec equals 206, 265 AU, how many miles is it equal to? unit of distance equal to about 3.26 light years (or 206,265 AU) If one parsec equals 206, 265 AU, how many miles is it equal to?

“Big Bang” Theory the primeval explosion of space, time, matter and energy that most astronomers think gave rise to the universe as we see it today. occurred about 13.7 billion years ago thought to have expanded within a second from something the size of a spec of dust to the size of our solar system Misconception Alert: Describing this theory as the “Big Bang” is a misnomer because there really was not an explosion, just a release of energy

Electromagnetic (EM) Radiation Majority of astronomy looks at EM Radiation EM Radiation – includes all radiation (light) from Radio to Gamma Rays Humans only see small region Visible light – 400 – 700nm (violet to red)

Constellation a group of stars that form a pattern in the sky stars of a constellation are often far apart from each other, but they appear grouped together when viewed from Earth

Why is it not possible to see all constellations at once? 88 constellations in the night sky patterns of constellations are dynamic; therefore, the constellations of 100,000 years ago are quite different from today’s a part of a constellation that forms its own pattern in the sky is known as an asterism (ex. – The Big Dipper) Why is it not possible to see all constellations at once?

Edwin Hubble determined that other galaxies exist, besides the Milky Way observed that galaxies were moving away from each other based on Doppler Effect Light is shifted toward red end of spectrum meaning its moving away from us Hubble Law – the farther away a galaxy is, the faster it is moving away from us; supports the Big Bang Theory

Telescope a device that gathers and focuses electromagnetic radiation Types: Visible, infrared, ultraviolet – pick up visible, infrared, and ultraviolet waves Reflecting - use mirrors that reflect the image being viewed Refracting – using lenses, gathers light and focuses it near the opposite end of the tube; works like a magnifying glass Radio - pick up radio waves emitted from space; not effected by variables like weather or clouds

Hubble Space Telescope a reflecting telescope that was placed into orbit in 1990 sends images and measurements back to Earth electronically Taken several long exposure images called “Deep field” Image taken from: http://hubblesite.org/gallery/ What is one of the main benefits of having the Hubble Space Telescope in orbit, as opposed to it being here on Earth?

Hubble Deep Field

Arno Penzias & Robert Wilson accidentally detected faint radiation on a radio telescope in 1965 determined that the radiation was leftover thermal energy from the “big bang” about 300,000 years after it happened Called cosmic background radiation

Discovery of the Background Radiation from initial Big Bang -Long wavelength -came from all directions Penzias and Wilson, 1965 Arecibo Dish, Puerto Rico

Cosmic Background Radiation

Galaxy a large assemblage of stars (and often gas and dust), typically containing millions to hundreds of billions of member stars Star - a large hot ball of gas which generates energy in its core by nuclear reactions estimated 100 billion galaxies in the universe each with billions of stars held together by the gravitational attraction of all its member stars on one another formed around 200 million years after the “Big Bang” most large galaxies have super-massive black holes at their centers sometimes contain very bright centers called quasars 3 major types: Spiral Elliptical Irregular What is the name of the galaxy we reside in?

3 Types of Galaxies Elliptical shaped like spheres or eggs; have almost no dust or gas between stars; contain old stars Irregular faint galaxies without a definite shape; smaller than the other types of galaxies; contain fewer stars Spiral have arms of stars, gas , and dust that curve away from the center of the galaxy in a spiral pattern Ex. – Milky Way The process of galaxies colliding to create a larger galaxy is known as “galactic cannibalism.”

Our Solar System the Sun and all things orbiting around it, including the eight major planets, their satellites, and all the smaller pieces such as asteroids and comets formed around 4.6 billion years ago Formation called Nebular Hypothesis Theory Solar system formed from massive rotating disk of gas (hydrogen and helium) and dusk What is incorrect or misleading about this visual?

Planet derived from a Greek word that means “wanderer” a major object which orbits around a star in our solar system, there are eight such objects which are traditionally called “planets”

Asteroids small, solid, rocky bodies that orbit close to the Sun most found between the orbits of Mars and Jupiter in the “Asteroid Belt” thought to be leftover material from the formation of the solar system range in size from 1000 km or 621 miles (Ceres) to the size of pebbles

Meteoroid, Meteor, Meteorite Meteoroid (asteroid) Meteoroid – solid debris from space (asteroids) that are moving towards Earth Meteor a brief streak of light produced by a small particle entering Earth’s atmosphere at high speed often referred to as “shooting stars” or “falling stars” Begin to burn up in the Mesosphere travel at speeds between 11-72 kilometers per second (6.8 – 44.7 miles per second) Meteorite – a small object from outer space that passes through Earth’s atmosphere and reaches the surface Russian Meteor Strike Video Meteor Meteorite The Earth animation is not rotating in the correct direction; it should be rotating from west to east What causes a meteor shower to occur?

Comet a small body of ice and dust (“dirty snowball”) that orbits the Sun contain a head (coma) followed by a tail(s) of gas and dust the tail always points away from the sun and can be millions of kilometers long (but the amount of matter it contains can be very small)

Satellite an object that orbits a more massive object (i.e. – moons) probes we launch into orbit around the Earth are called “artificial satellites” The Earth animation is not rotating in the correct direction; it should be rotating from west to east

Universe Video Latest Hubble Deep Field

Edwin Hubble at Mt. Wilson Hubble’s observations at the 100 inch during the 1920’s led him to the conclusion that the universe is expanding, and that an object’s recession velocity is proportional to its distance from the observer. Hubble guiding the Hooker 100 inch telescope in 1923. The Hooker 100 inch telescope atop Mt. Wilson near Pasadena, CA. It was the largest telescope in the world from 1917-1947.

Deep Hubble Space Telescope Image A deep image of an “empty” portion of the sky with the Hubble Space Telescope reveals that the universe is filled with galaxies- many just like our own. The light we see from the most distant galaxies has traveled approx- imately 10 billion years to reach us.

Using the Doppler Effect to Measure Velocity Redshift Blueshift

Galaxy Spectroscopy Spectra of a nearby star and a distant galaxy Star is nearby, approximately at rest Galaxy is distant, traveling away from us at 12,000 km/s Stellar Spectrum Sodium Magnesium Galaxy Spectrum Calcium

Origin of the Universe - Did It Begin with a Big Bang?