Lecture 6

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School

University of Virginia *

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1210

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Astronomy

Date

Oct 30, 2023

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docx

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Uploaded by ProfessorLightningPuppy25

Announcements ● HW 2: our place in the universe & light ● Read the RRRT lab before Wednesday’s class Spectroscopy ctd. The Power of Spectroscopy: What is this object? ● ● MARS, for some bullshit reason Telescope Basics Goals for learning ● Understand what types of telescopes astronomers use and how they work ● Know the most important characteristics of a telescope and how we compare/calculate those characteristics ● Know where astronomers place telescopes and what types they use to observe various phenomena Refraction ● Refraction is the bending of light when it passes from one substance into another ● Your eye uses refraction to focus light Forming Images ● The focal plane is where light from different directions comes into focus ● The image behind a single (convex) lens is actually upside down! ● The focal plane are where detectors are placed to learn from light Refracting Telescopes ● Refracting telescopes need to be very long, with large, heavy lenses Reflecting Telescopes ● Example: Fan Mountain Observatory ● Reflecting telescopes can have much greater diameters ● Most modern telescopes are reflectors What do we do with telescopes? ● Imaging : taking pictures of the sky ○ Includes examining light we cannot see with our eyes

● Spectroscopy: breaking light into spectra ● Time Monitoring: measuring how light output varies with time ○ A light curve represents a series of brightness measurements made over time What are the Most Important Properties of a Telescope? ● Light-collecting area (or Light Gathering Power): ○ Telescopes with a larger collecting area can gather a greater amount of light in a shorter time Light-Collecting Area ● A telescope’s diameter tells us its light-collecting area: ● A = πR 2 = π(D/2) 2 = π/4D 2 ● The largest optical telescopes currently in use have a diameter of about 10 meters What are the two most important properties of a telescope? ● Light-collecting area (or light gathering power) : telescopes with a larger collecting area can gather a greater amount of light in a shorter time ● Angular resolution : Telescopes that are larger are capable of taking images with greater detail. ● Location! : more on this next lecture

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