Sign in to confirm you’re not a bot
This helps protect our community. Learn more

Distances: Crash Course Astronomy #25

CrashCourse
16.6M subscribers
2M views 10 years ago
How do astronomers make sense of the vastness of space? How do they study things so far away? Today Phil talks about distances, going back to early astronomy. Ancient Greeks were able to find the size of the Earth and from that the distance to and the sizes of the Moon and Sun. Once the Earth/Sun distance was found, parallax was used to find the distance to nearby stars, and that was bootstrapped using brightness to determine the distances to much farther stars. Check out the Crash Course Astronomy solar system poster here: http://store.dftba.com/products/crash... -- Chapters: Introduction 00:00 How did we calculate the Earth's Size? 1:07 THE Astronomical Unit (AU) = 149,597,870.7 km 3:12 Depth Perception & Parallax 5:39 Light Years & Parsecs 7:31 Brightness Indicates Distance 9:07 Review 10:30 -- PBS Digital Studios:    / pbsdigitalstudios   Follow Phil on Twitter:   / badastronomer   Want to find Crash Course elsewhere on the internet? Fa …...more
...more
University-Style Sweatshirt 3XL
$45.00
Complexly Store
Orientation week for rising Freshmen includes getting familiar with the layout of the campus, social mixers, and a visit to the college bookstore. There you'll pick up your books, supplies, and probably your university-style sweatshirt. Wearing your school's logo shows your pride in receiving a high-quality education there. This sweatshirt performs the same function! Show your pride that you've learned so much from Crash Course. DETAILS Dark Blue crewneck sweatshirt with Crash Course logo 80/20 Cotton Polyester Blend Show pride in your education! Please note: this item is printed on-demand and will ship within 14 business days of ordering. Your entire order will ship together at this time. Please plan accordingly.
Shop
Complexly Store
Crash Course Composition Notebooks - 3 Pack
$10.00
Complexly Store
This set of 3 composition notebooks is a great way for you to continue your journey towards being a lifelong learner, as well as a great way to support Crash Course! 100 pages each, college ruled, featuring interior artwork, diagrams, and facts only Crash Course can provide!
Shop
Complexly Store
Crash Course - Lifelong Learner Tee L
$32.00
Complexly Store
I found myself surrounded by people who celebrated intellectualism and engagement, and who thought that my ironic oh-so-cool disengagement wasn’t clever, or funny. It was a simple and unspectacular response to very complicated and compelling problems. And so I started to learn, because learning was cool. - John Green
Shop
Complexly Store
Crash Course Animal Cell Poster
$20.00
Complexly Store
The cell is the basic unit of life--and it's one busy place! This poster takes you on a tour of an animal cell, from its protein-studded cell membrane to its hard-working ribosomes. It includes facts about some of the most incredible animals around and key scientific leaps that have advanced our knowledge of cells. DETAILS 18"x24" Portrait Print 100lb Semi Gloss paper Artwork by Thought Cafe for Crash Course
Shop
Complexly Store
Crash Course Plant Cell Poster
$20.00
Complexly Store
Journey into the gravity-defying, sunlight-harvesting world of a plant cell. This poster takes you on a tour of what's beneath the cell wall, teaches you amazing plant facts, and introduces you to key leaps in our understanding of the basic unit of life. DETAILS 18"x24" Portrait Print 100lb Semi Gloss paper Artwork by Thought Cafe for Crash Course
Shop
Complexly Store
Crash Course - La Célula Animal Póster
$20.00
Complexly Store
La célula es la unidad básica de la vida... ¡y es un lugar muy concurrido! Este póster te lleva a un recorrido por una célula animal, desde su membrana celular llena de proteínas hasta sus ribosomas, que trabajan duro. Incluye datos sobre algunos de los animales más increíbles que existen y avances científicos clave que han hecho avanzar nuestro conocimiento sobre las células. DETALLES Impresión vertical de 18" x 24" Papel semibrillante de 100 lb Obra de arte de Thought Cafe para Crash Course
Shop
Complexly Store
Distances: Crash Course Astronomy #25
27KLikes
2,001,840Views
2015Jul 17
How do astronomers make sense of the vastness of space? How do they study things so far away? Today Phil talks about distances, going back to early astronomy. Ancient Greeks were able to find the size of the Earth and from that the distance to and the sizes of the Moon and Sun. Once the Earth/Sun distance was found, parallax was used to find the distance to nearby stars, and that was bootstrapped using brightness to determine the distances to much farther stars. Check out the Crash Course Astronomy solar system poster here: http://store.dftba.com/products/crash... -- Chapters: Introduction 00:00 How did we calculate the Earth's Size? 1:07 THE Astronomical Unit (AU) = 149,597,870.7 km 3:12 Depth Perception & Parallax 5:39 Light Years & Parsecs 7:31 Brightness Indicates Distance 9:07 Review 10:30 -- PBS Digital Studios:    / pbsdigitalstudios   Follow Phil on Twitter:   / badastronomer   Want to find Crash Course elsewhere on the internet? Facebook -   / youtubecrashcourse   Twitter -   / thecrashcourse   Tumblr -   / thecrashcourse   Support CrashCourse on Patreon:   / crashcourse   -- PHOTOS/VIDEOS Lunar Ecplise http://www.slate.com/content/dam/slat... [credit: Phil Plait] Venus & Mercury [credit: Phil Plait] Venus Transit    • Ultra-high Definition View of 2012 Venus T...   [credit: NASA] Black Drop Venus Transit https://en.wikipedia.org/wiki/Black_d... [credit: Wikimedia Commons, H. Raab, Johannes-Kepler-Observatory] New Horizons Approaching Pluto and Charon https://en.wikipedia.org/wiki/New_Hor... [credit: NASA/JHU APL/SwRI/Steve Gribben] Radio Telescopes Diagram http://scitechdaily.com/images/Radio-... [credit: Alexandra Angelich, NRAO/AUI/NSF] 61 Cygni https://archive.stsci.edu/cgi-bin/dss... [credit: Caltech / National Geographic Society / STScI] Proxima Centauri https://www.spacetelescope.org/images... [credit: ESA/Hubble & NASA] Dying Star http://www.nasa.gov/images/content/64... [credit: NASA, ESA, HEIC, and The Hubble Heritage Team (STScI/AURA)] Exploding Star http://www.nasa.gov/multimedia/imageg... [credit: NASA, ESA, J. Hester, A. Loll (ASU)] Animation of a Variable Star http://www.spacetelescope.org/videos/... [credit: NASA, ESA, M. Kornmesser] Hubble's High-Definition Panoramic View of the Andromeda Galaxy http://hubblesite.org/newscenter/arch... [credit: NASA, ESA, J. Dalcanton, B.F. Williams, and L.C. Johnson (University of Washington), the PHAT team, and R. Gendler]

Follow along using the transcript.

CrashCourse

16.6M subscribers