TEK Objective 4: The student knows how Earth-based and space-based astronomical observations reveal differing theories about the structure, scale, composition, origin, and history of the universe. Student Expectations: a) evaluate the evidence concerning the Big Bang model such as red shift and cosmic microwave background radiation and current theories of the evolution of the universe, including estimates for the age of the universe; b)explain how the Sun and other stars transform matter into energy through nuclear fusion; and c) investigate the process by which a supernova can lead to the formation of successive generation stars and planets. The Origin and History of the Universe

How did our universe begin? How old is our universe? How did matter come to exist? What is our place in the universe? Homo neanderthalensis Galileo True to the nature of science, a majority of these answers have only led to more intriguing and complex questions. Perhaps, science is all about finding the next question, instead of the answers!

Universe Galaxy Star, or Stellar System Planetary, or Solar Systems The universe is commonly defined as the totality of everything that exists, [ including all space, time, matter, energy, planets, stars, galaxies, and intergalactic space [ A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas, dust, and dark matter. Our galaxy is the Milky Way, and it is a spiral galaxy. Messier 100 (M100) Spiral Galaxy A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A solar system consists of one or a number of stars, surrounded by a number of planets and planetary bodies held by gravitation. dark matter is matter that is inferred (not actually seen) to exist. It neither emits nor scatters light or other electromagnetic radiation (and so cannot be directly detected via optical or radio astronomy

Universe had no beginning or end…it was truly infinite With the Big Bang theory, universe is “finite”: 15 billion years ago, huge explosion which started the expansion of the universe. all matter, and energy of space was contained at one point. this explosion filled all of space with the particles of the young universe rushing away from each other. Edwin Hubble Observed the universe expanding in every direction and that a galaxy’s velocity is proportional to its distance from us. Ex: galaxies that are twice as far from us, move twice as fast

This mathematical derivation (calculation) can only be correct, however, if the universe is not significantly accelerating or decelerating its expansion rate. If the rate of expansion is rapidly accelerating, the universe may be older than 15 billion years. 1)by looking for the oldest stars; and 2) by measuring the rate of expansion of the universe and extrapolating back to the Big Bang ( Recessional Velocity ) This second way uses what is known as the Hubble constant to measure of the current expansion rate of the Universe.

One way to measure these ages is with the travel time of light. Light travels incredibly fast – 300,000 kilometers per second. 8.3 minutes from the Sun, 4.3 years from the nearest star, 8500 years from the center of the Milky Way galaxy. We don’t see these objects as they are right now, but as they were when the light left. The universe actually works as a sort of “time machine,” in which we can see into the past simply by looking far away. Speed of light Distance of objects ( Well known from experiments here on Earth) ( Far more difficult) Some galaxies look much smaller and fainter than others, showing they may be much further away. The Andromeda galaxy is 2.3 million light years away. That is, we are seeing it as it was 2.3 million years ago. In recent decades, astronomers have detected galaxies located several billion light years away. If the light has been traveling billions of years to reach us, then the universe must be at least that old. Galaxy UDFj is the oldest galaxy to ever be found, estimated at 13.7 billion light years from Earth.

Galaxies are not holding still in space, nor are they moving randomly. From the time of the Big Bang, the Universe has been expanding in a uniform manner and direction. Towards one another (gravity) Away from one another (momentum from the Big Bang) While objects within the Universe have been expanding, for the most part, in a uniform manner, the motion apart has not all been at the same speed; instead it follows a pattern where galaxies that are further apart are moving more quickly. Speed of galactic motion is proportional to the separation between them. This, again, is known as Hubble’s Law. Astronomers detect a galaxy’s motion by looking at its light spectrum.

1.Who was one of the first cosmic observers to use a telescope? 2.Describe each of the structures in the Universe, from largest to smallest. 3.What is dark matter, and why can’t it be detected via optical (light) or radio astronomy? 4.How old do scientists think the Universe is, and how do they know? 5.Who can be credited with discovering the origin of the Big Bang? 6.A Galaxy’s ______ is directly proportional to its ______ from Earth. 7.What is a simpler way to describe the above?

This movement would tend to make objects (or galaxies) that we are most distant to appear “reddish” This is the name given to the phenomenon of galaxies moving farther away from each other. As light approaches Earth from different galaxies, the space between that distant galaxy and Earth increases. This leads to wavelengths of the light being stretched. Why red???

Remember…the longer wavelengths of the visible light spectrum include the reds and oranges. The shorter wavelengths of the visible light spectrum include the indigos and violets, so the farther away the stars become, the “more red” they appear

When a galaxy is carried away by the expansion of space, its light waves are stretched out, making it appear redder. This red shift can be used to calculate the galaxy’s velocity. From the measurements of many galaxies, astronomers can accurately measure the expansion rate of the universe as a whole. The age of universe can be determined by imaging what the universe looked like in the past, “rewinding” the expansion. In the past the galaxies must have been closer together, and in the distant past they would have been packed together in a tiny point. If we assume that the expansion rate is constant over time, the age for the universe as a whole is about 10 billion years. Astronomers have been working over the last 20 years to determine how the expansion rate changes with time. We now know that early in the universe the expansion was slowing down, but now it is speeding up. Using careful measurements of this change in expansion rate, the age of the universe is now known quite precisely to be 13.7±0.13 billion years Hubble's Law

is thermal radiation filling the observable universe almost uniformly. It is radiation left over from an early stage in the development of the universe, and its discovery is considered proof of the Big Bang model of the universe. Scientists use very small radio telescope arrays to listen to CMBR.

9. Why do objects (or galaxies) tend to appear reddish when they are farther away? 10. In the electromagnetic spectrum, the longer wavelengths of visible light are the ____ and ____, while the shorter include the _____ and _____. 11.Using the above information, what color would you expect the closest galactic objects (galaxies) to be when viewed through a telescope? 12.On the EM spectrum, what forms of low frequency energy are found below the visible light spectrum? 13.What high frequency energy forms are found above the visible light spectrum? 14.What is CMBR, and how do scientists use it as proof of the Big Bang? 15.What does the Big Bang sound like to you?

Our sun is in the “main sequence” of its life. The layers of the Sun show temperature highest at the core and progressively decreasing as we move out towards the exterior. The whole of solar mass is gaseous and mostly composed of hydrogen and helium. As the hydrogen is replaced by helium (nuclear fusion), these numbers flip-flop during its life. At its core, the Sun fuses 620 million metric tons of hydrogen each second. At this average distance, light travels from the Sun to Earth in about 8 minutes and 19 seconds, and is largely emitted by the photosphere. The only time we truly get to see the sun’s corona (atmosphere) is when there is a solar eclipse. At birth, the star has plentiful hydrogen. As it consumes hydrogen through fusion, helium increases.

The sun represents a source of light and heat upon which all living things depend for their survival. This light and heat radiated by the sun is the result of fusion energy. Fusion converts matter to energy. Fusion is the joining of two small elements to form one larger one. In the process, energy is lost, in the form of light and heat. The main fuels used in nuclear fusion are deuterium and tritium, both heavy isotopes of hydrogen. This energy, once it reaches the Earth, is then utilized by plant life to build tissue, and repair injury, as well as maintain homeostasis. Then animals and microscopic consumers eat the plants, delivering the energy to their bodies. Consumers use this energy for the same purposes as plants.

A supernova is a stellar explosion that is more energetic than a nova. It represents the “death” of a star. It is this remnant, or stellar “dust” which has the potential to form new stars and even planets. The explosion expels much or all of a star's material [ at a great velocity driving a shock wave into the surrounding space. This shock wave sweeps up an expanding shell of gas and dust called a supernova remnant. [

Supernovas may occur in two ways: After the core of an aging massive star (red giant) stops creating energy from nuclear fusion, it may undergo sudden collapse into what they call a neutron star or black hole, releasing gravitational potential energy that heats and expels the star's outer layers. Alternatively, a white dwarf star may accumulate sufficient mass from a stellar companion (through accretion, or merger) to raise its core temperature high enough to undergo runaway nuclear fusion, completely disrupting it.

16.What is the energy source of stars? 17.What two main isotopes fuel our Sun’s energy? 18.How does life on Earth rely upon the Sun’s energy? 19.Describe how a Supernova can be the end, and the beginning. 20.In what two ways may supernovas occur?