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ASTRONOMY Tools of the ASTRONOMER

OBJECTIVES By the end of this presentation, students will be able to… Explain the value of each tool used by the astronomer. Compare the similarities and contrast the differences between the types of telescopes.

Naked EYE What is visible: The sun The moon 5 planets 25 Open Clusters (loose groups of stars) 9 Globular clusters 8 Nebulae (gas clouds) The Milky Way About 6000 Stars (Mercury, Venus, Mars, Jupiter, Saturn)

Binoculars ADVANTAGES: Easy to use Very portable Relatively inexpensive Provides a wide field of view Ideal for beginners Useful for advanced viewers

Binoculars USES: Help find way around constellations (especially in the city) See double stars more sharply Better resolution of star clusters Following artificial satellites Locate and identify planets View surface features of the moon NEVER, EVER look into the sun!!!

Binoculars SPECIFIED DESIGNATIONS: Binoculars are designated using two numbers M – magnification –The greater the magnification, the dimmer the object and smaller the field of view APERTURE – diameter of the front lens –The greater the Aperture, the brighter the object Optimal designation: M : APERTURE = 1 : 5 6x 30; 7x 35; 8x 40; 10x 50

Optical Telescope PURPOSES: To gather more light than the human eye –The Light Gathering Power increases with increasing lens diameter. – LGP = D 2 (D is measured in cm.) –The Limiting Magnitude is the dimmest an object can be to be seen though the telescope. – Mag Lim = log D

Optical Telescope PURPOSES: To resolve (separate) two distant objects –The Resolution of a telescope measures how well a telescope can form a sharp image; how close two points can be before they look like one point. – R = 116/D (R is measured in sec of arc)

Optical Telescope PURPOSES: To magnify the image formed – Mag = f o / f e – Increasing the magnification is done by decreasing the f e. – Highest Magnification = 20 D

Optical Telescope TYPES: Refractors – gather light using an objective lens –Relatively inexpensive –Easier to use than reflectors –Good quality optics yield best resolution Eyepiece Objective Lens f e f o

Optical Telescope TYPES: Reflectors – gather light using an objective mirror –Greater LGP and magnification –Easier to build than refractors –Lightweight and better resolution Eyepiece Objective Mirror f e f o

Optical Telescope TYPES: Multiple Mirror Reflectors – gather much more light using many mirrors as the objective mirror. –VERY expensive –Allows viewing very dim objects Objective Mirror

CCD Telescopes The Charge Coupled Device is an array of photocells that collects the light gathered by the telescope and generates a digital image of the object. This image is stored electronically and retrieved for later viewing. The CCD is more sensitive to light; Can see farther into space with more detail; Is sensitive to a broader range of light, not just visible light.

CCD Telescopes The CCD is sensitive to a broader range of light, not just visible light: Radio Telescopes Microwave Telescopes Infrared Telescopes. Visible Light (Optical) Telescopes. Ultraviolet Light Telescopes. X-Ray Telescopes. Gamma Ray Telescopes. Receiver (CCD enclosed) Objective Dish

The Spectroscope is a device used to separate starlight into its various colors. The resulting picture is the spectrograph. Allows astronomers to analyze the elemental composition of a star. Spectroscope Columnating lenses Prism CCD Slits

Spectroscopy is the science of determining the composition of something from the light it emits. WHITE LIGHT HYDROGEN HELIUM IRON CALCIUM Spectroscopy

Different types of spectra form from different objects. Continuous Spectra form from glowing solids, liquids, or hot compressed gases. Bright-Line, or Emission Spectra form from glowing gas vapors. Dark-line, or Absorption Spectra form from a continuous spectrum passing through a dark gas cloud or atmosphere. Spectroscopy

Different types of spectra form from different objects. Continuous Spectra. Bright-Line Spectra. Dark-line Spectra Spectroscopy

Electromagnetic energy is radiant energy that travels through space in waves. The speed at which it travels is a constant 300,000 km/s or 186,000 mph. Speed of light = wavelength x frequency c = x Wavelength – the distance from crest to crest. Frequency – the number of waves generated each second. Electromagnetic ENERGY

The full range of wavelengths and frequencies that are characteristic of this energy. Divided into bands for classification and easier study. Each band is categorized based on its use or source. Electromagnetic Spectrum

Radio Microwave Infrared Visible Light Ultraviolet Light X-Ray Gamma Ray Electromagnetic Spectrum Red Orange Yellow Green Blue Indigo Violet LONG WAVELENGTHSLOW FREQUENCIESLOW ENERGIES SHORT WAVELENGTHSHIGH FREQUENCIESHIGH ENERGIES

ASTRONOMY The Night Time Sky The Celestial Sphere