The Universe

1. The Universe

2. Cosmology • the branch of astronomy that deals with the origin, large-scale properties, and the evolution of the observable universe

3. The Universe • in astronomy, the 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 Can you think of something in the universe that cannot be seen, but its effects on other things can be detected?

4. “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

5. Edwin Hubble • determined that other galaxies exist, besides the Milky Way • observed that galaxies were moving away from each other • Hubble Law – the farther away a galaxy is, the faster it is moving away from us; supports the Big Bang Theory Image taken from: http://apod.nasa.gov/apod/ap960217.html

6. 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” Image taken from: http://www.einstein-online.info/en/elementary/cosmology/early_universe/index.html

7. 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 • around 100 billion in the universe • 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 ones seem to 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?

8. 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.” Images taken from: http://school.discoveryeducation.com/schooladventures/universe/galaxytour/toknow.html

9. 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 • one of 88 sectors into which astronomers divide the sphere of the sky – named after a traditional constellation in that sector • 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?

10. 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 What is incorrect or misleading about this visual? Image taken from: http://asm.arc.nasa.gov/Gallery/images/generic/LG_Capableofeverything.jpg

11. 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”

12. 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 Image taken from: http://www.windows.ucar.edu/tour/link=/our_solar_system/asteroids.html

13. 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” • 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 • Freehold Meteorite - MSNBC • Freehold Meteorite - USA-Today 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?

14. 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) Image taken from: http://www.space.com/bestimg/index.php?guid=45b0fd31f065d&cat=bestcomet

15. 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

16. Telescope • a device that gathers 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 Internet Telescope

17. Hubble Space Telescope • a reflecting telescope that was placed into orbit in 1990 • sends images and measurements back to Earth electronically 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?

18. 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.)

19. 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?

20. Parsec • 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?

21. Parallax • the apparent shift in position of an object when viewed from different locations • used by astronomers to measure distance Put your pointer finger in front of your face and begin opening and closing your eyes in an alternating manner. What do you notice about the your finger’s position? Parallax Simulation Parallax Simulation – 1 Parallax Simulation - 2 Find the Distance to HT Cas Using Parallax