Announcements Im enjoying reading your projects! Turn in homework 8 by 5:00 today Pick up Homework 9. Test this week (W, Th, F before class) To put things in perspective, try Zoomer! (linked at bottom of course web page)
Tonight is a great time to start the Phases of the Moon project! Course Outline Naked-eye astronomy Crash course in physics Our solar system
The stars Structure and history of the universe Course Outline Naked-eye astronomy Crash course in physics
You are Our solar system here The stars Structure and history of the universe Measuring the Stars 23 October 2006 Today: How we determine the properties of stars: distance, motion, brightness
A survey of the stars in our neighborhood How far away are the stars? A clue: Compare brightness of our sun to brightness of stars . . . Its the difference between night and day! Measuring distances by parallax Baseline A
Angle = ? Nearby star B Approximation: Measure the angle between A and B from the baseline instead of from the nearby star. As long as the background stars are many times farther away, the difference is negligible. Background stars
Measuring distances by parallax Baseline Big Circle Problem: Nearby star How many baselines would fit around the
circle? Whats the circles circumference? Whats the circles radius? Measuring distances by parallax
2 A.U. Example (nearest star): Nearest star (Baseline is earths orbit around sun!)
Angle = 1.5 seconds of arc (1/2400 degree), so 864,000 baselines would fit around circle (360 x 2400). Circumference = 1.7 million A.U.
Radius = 275,000 A.U. (circumference / 6.28) Alpha Centauri How far is 275,000 A.U.? Light-travel time: Light takes 8.3 minutes to travel 1 A.U., so to reach us from the nearest star, it takes 2.3 million minutes, or 4.3 years. In our scale model, 1 A.U. is 100 feet. Then the nearest star is 27.5 million feet away, or 5200 miles. So far, humans have traveled 1/400 A.U.; robotic
spacecraft have traveled 100 A.U.; interstellar travel will not be practical any time soon! Space is Big. Space is big. Really big. You just won't believe how vastly hugely mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space To be fair though, when confronted by the sheer enormity of the distances between the stars, better minds than the one responsible for the Guide's introduction have faltered. Some invite you to consider for a moment a peanut in Reading and a small walnut in Johannesburg, and other such dizzying concepts. The simple truth is that interstellar distances will not fit into the human
imagination. --Douglas Adams The Hitchhiker's Guide to the Galaxy History of Parallax Measurements 1838: First successful stellar parallax measurement by Friedrich Wilhelm Bessel 1990: A few hundred stellar parallaxes measured by now, out to about 100 lightyears. Atmospheric blurring makes further measurements from earths surface virtually impossible. 1990s: Hipparcos satellite, launched by European Space
Agency, measures more than 100,000 parallaxes, out to more than 1000 light-years. Stellar Motion Radial motion (toward or away from us): Measured by Doppler shift of spectral lines. Proper motion (across the sky): Measured by observing changes in a stars position compared to background stars. Typical speeds of nearby stars (relative to us): a few tens of kilometers per second, or roughly 1/10,000 the speed of light.
Directions are mostly random. Parallax and Proper Motion
Now, contracts with potential of $100-500M include work with the follow-on to GPS, new attack submarine (NSSN), combat simulations (CCTT), information services (DMS, SBIS), as well as work updating sofware for the FAA, IRS and the postal service (DPS) Now...
Gray-out Post Ck Box on Edit Journals Page. CR 133. Add Field to INF 19. Cr 142. Change INF 39 (Incremental data tfr) CR 145. Update SHARP EIP Data in SMART -GL BU. CR 139. Training Sandbox Environment *Was estimated...
Themes in The Outsiders. What is a theme? A theme is a main idea or an underlying meaning of a literary work, which may be stated directly or indirectly. Things are rough all over. Nothing gold can stay. Change will...
What can emission lines tell us? lecture 2 Grażyna Stasińska Diagnostics based on emission lines plasma diagnostics: electron temperature, density ionic and elemental abundances - direct methods elemental abundances - statistical methods estimation of the effective temperature of the ionizing...
It is interesting to watch the interaction between the English-only students and the limited-English proficiency students when faced with having the tables turned. You can also include art, poetry or history assignments which require cross-discipline involvement.
Particularmente el Distrito Río Blanco-Los Bronces cuenta con alrededor de 200MT de recursos de cobre identificados convirtiéndose en una oportunidad de crecimiento significativa para la industria. INICIATIVA 3: PUESTA EN VALOR CORDILLERA .
This presentation provides a description of the Statutory Authority and Review Process for the regulation of genetically engineered animals at the FDA. Description "This presentation describes the history of the regulation of GE Animals in the U.S. Government as well...