ASTR 1345 1st Edition Lecture 13 Outline of Last Lecture I. More Properties of Light A. PolarizationB. Diffraction1. Diffraction GratingC. Interference 2. Constructive Interference3. Destructive Interference II. Why the Sky is BlueIII. Transparency of Earth’s AtmosphereOutline of Current Lecture I. Telescope PartsA. Focal PointB. Focal LengthC. Focal PlaneD. Eyepiece LensE. MagnificationII. LensesA. Convex LensesB. Concave LensesC. Objective LensesIII. Refracting TelescopeA. Spherical Aberration (Problem and Solution)B. Chromatic Aberration (Problem and Solution)IV. Reflecting TelescopeA. Problem and SolutionV. TwinklingCurrent Lecturel.A. The focal point is the place at the focal length where light rays from a point object (one that’s too distant or tiny to resolve) are converged by a lens or concave mirror.B. Focal Length is the distance from a lens or concave mirror to where converging light rays meet.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.C. Focal Plane is the plane at focal length of a lens or concave mirror on which an extended object is focused.D. Eyepiece lens—magnifying lens used to view image produced at focus of telescope.E. Magnification is the number of times larger in angular diameter an object appears through a telescope than when it is seen by the naked eye.ll.A. Convex lenses are lenses that’re thicker at their centers than at the edges. They cause the light that enters them to converge.B. Concave lenses--thinner at centers than around edges, cause light rays to diverge.C. Objective lenses are the principle lens in a refracting telescope (large convex lens). Large objective lenses use parabolic mirrors because 1. Neither spherical aberration nor chromatic aberration occur 2. They weigh less than large glass lenses 3. Unlike glass lenses, metal mirrors are structurally stable.lll.A refracting telescope or refractor is a telescope in which the principal light-gathering component is a lens.A. A problem with a refracting telescope could be spherical aberration. This is an opticalproperty where different proportions of a spherical lens or spherical concave mirror have slightly different focal lengths, producing a fuzzy image. A solution is making the lens very thin with a long focal length.B. Another problem could be chromatic aberration which is an optical property where different colors of light passing through a lens are focused at different distances fromit. A solution is combining 2 lenses made from 2 different types of glass.lV.A reflecting telescope or reflector is a telescope in which the principle light-gathering component is a concave mirror or spherical mirror. A. A problem with the reflecting mirror is that different parts of the mirror focus the light at different distances from the mirror. A solution to this is grinding the mirror to a parabolic shape.V.Twinkling is the change in a star’s brightness, position, or color due to the motion of gases in Earth’s