OVERVIEW OF ASTRONOMY

1. OVERVIEW OF ASTRONOMY JIM KONICHEK

2. I star distance is great- nearest is 250,000 A.U.’s • A. chances of collision is minute • 1. the A.U. is too small of a unit to express star distance • a. use the light year- The distance light can travel in one year( 6 trillion miles) • b. nearest star is then 4.3 light years • c. average distance between stars is about 5 L.Y.

3. I.Overview of the solar system.(6.2) • A. Sun is dominant mass of the solar system • 1. 2xl0 33grams • 2. Composed of the same elements found on earth • 3. Tremendous pressures and temperatures • 4. Contains 99.85% of all the mass of the solar system. • 5. The visible portion of the sun 1,390,OOOKm across • a. 109 earth diameters • 6. Volume is 1.3million times that of earth • 7.energy output is 4x10 33 ergs per second-sun produces more energy in 1 s than mankind has ever used • 8. Gets energy from thermonuclear reaction • a. interior about 14 million degrees Kelvin • B. Planets- Most of planetary material is concentrated in the planets 1. Most concentration is in Jupiter.

4. C. Planets circle the sun in relatively the same plane of small eccentricity called the ecliptic • D Sizes vary from Jupiter which has a mass 1/1000 of the sun to pluto is smaller than our moon. • E. General breakdown of the planets • 1. Terrestrial planets- mercury, Venus, Earth, Mars • a. Rocky worlds • b. composition silica and metals • c. Some have atmospheres • 2. Jovian- gaseous- Jupiter, Saturn, Uranus, Neptune • a. lack solid surfaces • b. Lighter elements, H, He, Ar, C,O, N • 3. Pluto and other planetoids

5. INNER PLANETS

6. II.STAR FORMATION • A. condense out of a swirling cloud of dust and gas. • 1. Orion nebula is an example • a. very rarified vacuum- million time more rarified than those found on earth • 1. a study of this gas helps understand how rarified gases act. • 2. super condensed stars result in a very dense star whose 1 tablespoon of matter would weigh tons • 3. Molecular clouds- Not visible to the naked eye, detected by radio telescopes • a. largest single objects in the galaxy. • 1. too large to form a single star, cloud fragments and forms star clusters. • a. it is thought all stars originate in clusters. • b. most of the stars in the universe are bound up in multiple star systems. • 1. the sun is a minority star- a singleton star.

7. OUTER PLANETS

8. ORION NEBULA SITE OF STAR FORMATION

9. III.GALAXIES- contains all the planets, stars, star clusters, and intergalactic matter. • a. Milky way- 100LY across • 1. contains a four hundred billion stars, revolution time is 250 million years • 2. Part of the local group • 3. galaxy size varies- some may be regular or irregular shaped. spiral, elliptical.

10. ANDROMEDA GALAXY

11. IV MICROSCOPIC VIEW OF THE UNIVERSE • A. Astrophysics- the use of atomic physics to explain how various forms of radiation are created. • 1. a stars radiation is the summation of all the radiation given off by the individual atoms of the star( quantum mechanics). • a. the interaction of gravity holding the atoms together in the star and understanding the forces acting on the atoms. • b. The nuclear fusion process is the need for understanding the universe at an atomic level • 2. to understand the evolution of the universe the subatomic level must be understood. • a. The atom is mostly empty- Rutherford • b. has a dense core- nucleus, surrounded by a cloud of electrons. • c. Reasoned that the parts can be broken down even to smaller units called quarks, and these are created out of the collision of high emery photons of EMR

12. Gold foil experiment

13. V. ASTRONOMY AS AN OBSERVATIONAL SCIENCE • A. difficulties with doing astronomy • 1. astronomer can’t do controlled experiments • a. how would a black hole be constructed • b. How is it possible to repeat the experiment? • c. can’t examine things from different angles • d. Astronomers can- collect light and other forms of EMR and try to interpret what the light means • 1. Once the object has been visited by man it is no longer an astronomical object. • e. Astronomers can make observations which in turn become theories, hypothesis, and speculation. • 1. enables the astronomer to make predictions when given similar astronomical conditions • 2. evidence is often indirect, and supports more than one hypothesis. • 3. Questions are not resolved immediately, often after considerable time do questions get answers, when more sophist acted equipment is invented.

14. VI. THE ASTRONOMERS ADVANTAGE • A. Many phenomena cannot be created on earth, but can be done in the universe • 1. star creation- sustained nuclear fusion, Black holes • 2, rarified gas situations • 3. super massive objects

15. VII. THE ASTRONOMICAL TIME MACHINE • A. Light travels at A finite velocity- • 1 300,000,000 m/s • B. When looking into space we are seeing what is happening in the past • 1. Gives an idea as to what the destination for our solar system, galaxy is. • a. the evolution of a galaxy, star... ect.

16. VIII. ORDERS OF MAGNITUDE • A. Much like scientific notation- Give a way of representing very large numbers, or very small numbers B. using the earth’s diameter • 1. as a base where 104= 0 magnitude. Then we can compare everything to the earth in terms of magnitude. • a. 108 = 4

17. IX. THE EXPLOSION OF KNOWLEDGE IN THE TWENTIETH CENTURY • A. As of 1920 the entire size of the universe was thought to be only 20,000Ly • 1. has spread out to be 15-20 billion light years. • 2. Hubble says different though