ASTR 2020 ASTR 2020 Space Astronomy Space Astronomy Introduction ASTR 1200: Why Space Astronomy ? Limitation of Astronomy from the ground: Earths atmosphere is opaque at most wavelengths. Atmospheric Windows: Visual, near-IR, radio Turbulence: Limit angular resolution to ~1 arc-second Backgrounds: flux from various sources limits sensitivity. Visual: Light pollution (artificial lighting) Scattering (star-light, moon-light, Sun, etc.) Airglow (glowing atoms & molecules in upper atmosphere) Near-IR & radio: thermal emission from atmosphere Radio: Electronic interference (RFI = radio frequency interference) Atmosphere is opaque at most wavelengths . Diffraction: Light spreads as = / D (radians) In the `far field given by L = D 2 / D = Diameter of aperture (telescope optical diameter) D L Near field Far field (shadows) (diffraction) Airy pattern Seeing: Seeing: The impact of atmospheric turbulence on images of a star. Seeing-limited Diffraction limited = / D Diffraction limited: Ex: D = 1 m = 100 cm; = 0.5 m = 5x10 -5 cm = [5x10 -5 ]/[100] = 5x10 -7 radians ~ 0.1 arc-seconds Seeing limited: ~ 1 to 3 arc-seconds (1 radian ~ 206,265 arc-seconds) Backgrounds Backgrounds: Airglow as seen from Space Aurora + Light pollution + scattered star- and moon-light + Thermal emission at > 2 m (VERY BRIGHT!) + R.F.I. (Radio Frequency Interference) at > 1 cm Airglow We will meet at MWF 3:00 - 3:50 here (Duane G125) Homework (30%) to be given roughly every two weeks on Tuesday; due the following Tuesday, returned on the Tuesday after. Two Midterms (12.5% each ) Friday, 11 March; Friday, 8 April Comprehensive Final (25%) Wednesday, 4 May 7: :00 PM A Class Project (10%): I will ask you to evaluate & design an instrument to meet Dan Goldins Dream to image an exo-Earth with 100 km resolution- more on this later in class. Participation (10%) - Clilckers - Sommers-Bausch Observatory (SBO) observing: (6 sessions) - Visits to Fiske Planetarium (4 sessions) See Syllabus for dates/times ASTR 1200: Syllabus overview SBO dates / times: SBO dates / times: Fiske dates / times: Fiske dates / times: Wed, 3 Feb Intro to sky, space station, orbits of satellites around Earth, planetary and KBO orbits Wed, 24 Feb Exploration of Solar System bodies with robotic spacecraft: Moon, Mars, Jovian system,Saturn, and Pluto Friday, 18 March The multi-spectra sky: 3D exploration of the galaxy; Spitzer, Herschel/Hi-GAL, trip to Orion, Carina, etc. Wednesday, 13 April Overview of galaxies and cosmology: HST, deep fields, 3D distribution of galaxies, CMB Course Outline: Basics of the electromagnetic spectrum Propertied of EM waves, interaction with matter Nature of matter & the forces of nature Limitations of ground-based astronomy Basics of Gravity & motion Orbits, velocity, acceleration, propulsion Navigation in Space Basics of Optics and Remote sensing Exploration of the Solar System with robotic spacecraft: Mercury, Apollo, Voyager, Magellan, Galileo, Cassini, New Horizons Space Astronomy: Exploring the spectrum IRAS, Uhuru, HST, CXO, WISE, Spitzer, Herschel, GRO, Fermi, . In Instructors Instructors John Bally D349 Duane casa.colorado.edu/~bally/ Office hours: Tuesday 1:00 AM - 2:00 PM Wednesday 2:00 PM - 3:00 PM or by appointment Aaron Stemo E122 Duane Aaron Office Hours: Tuesday 11:30 AM-1:00 PM or by appointment Also available in the Astronomy Help Room (AHR) 4:00 PM - 6:00 PM Wednesdays Duane D220 Web page for Course Material Web page for Course Material casa.colorado.edu/~bally/Current_Course/ Syllabus.pdf Howework/ Lecture_ppt_files/ Some other interesting Web pages: My Background My Background Berkeley BS (1972) PhD U. Mass. Amherst (1980) Molecular Clouds, Star Formation, radio astronomy AT&T Bell Laboratories ( ) (in group which discovered CMB) mm-and IR astronomy star & planet formation CU Boulder ( present) - Hubble Space Telescope, South Pole - Herschel Space Observatory, . Birth of massive stars & clusters The Galactic Center Ecology of the Interstellar medium Cosmology The Golden Age of Astronomy & Physics: The Golden Age of Astronomy & Physics: Access to the entire EM spectrum: Giant ground-based telescopes, Sensors at visual, near-infrared, radio, UV, X-ray, & hard gamma-rays Access to space: No atmosphere: No attenuation or turbulence New phenomena and knowledge (dark matter, dark energy, nature of matter & energy) Understanding of Nature is the driver of the Economy ! Clicker Test: Clicker Test: The number of arc-seconds in a radian is: 1) 1 2) 200 3) 206,265 4) 2x10 6 The Golden Age: The Golden Age: Seeing what we cant see (with our eyes) - Electronics & silicon technology => sensors at all wavelengths - Large telescopes (Diameters up to 10 meters now; 37 meter in 10 yrs) - Space telescopes (to 6 meters) => No atmosphere => Sharp images => Access to all wavelengths Fermi Chandra Hubble Spitzer Herschel ALMA (Chile) -ray X-ray UV/visual IR sub-mm radio - Powerful computers => Model cosmic evolution, stars, atoms, NEW DISCOVERIES! Understanding nature => Enables technology, economy Understanding nature => Enables technology, economy Hubble Space Telescope Kitt Peak (visual) Very Large Array 27 x 25 m (radio) Green Bank 100 m (radio) Hubble 2.4 m (visual) Fermi ( -ray) Chandra (X-ray) CXO (X-ray) GRO ( -ray) James Webb Space Telescope meter diameter Earth-Sun L2 (~10 6 km from Earth): 2018 ASTR 2020 ASTR 2020 Space Astronomy Space Astronomy Friday The Electromagnetic Spectrum Electromagnetic Waves Whats waving? - Electric fields induce Magnetic fields - Magnetic fields induce Electric fields What is a field? - the force experienced by a charge (+,-) electrons e.g. electrons protons neutrons but not neutrons Wavelength A large, glowing ball of gas that generates heat and light through nuclear fusion Star Visual wavelength UV & X-ray wavelengths The Winter sky . Infrared view of winter sky ( m) Electromagnetic (EM) Waves - Properties of light : its a wave and a particle! - Wave like properties (EM waves) : frequency, wavelength [frequency] x [ wavelength] = [speed of light] f x = c x = c = f = c c = x cm/sec - Particle like properties (photons) : energy, momentum [energy] = h f = h h = Planck constant = x in (c.g.s) [momentum] = E/c = h f / c = h / c = h / because f = c / ) How can we know what the universe was like in the past? ZLight travels at a finite speed Zc = 300,000 km/s = 3 x cm/sec. ZThus, we see objects as they were in the past: The farther away we look in distance, the further back we look in time. DestinationLight travel time Moon1 second Sun8 minutes Sirius8 years Andromeda Galaxy2.5 million years No Calculators! Z A photon has wavelength =1.5x10 8 cm what is the frequency? a)4x10 -2 s -1 b)5x10 9 s -1 c)6x10 18 s -1 d)2x10 2 s -1 e)6x10 2 s -1 No Calculators! Z A photon has wavelength =1.5x10 8 cm what is the frequency? a)4x10 -2 s -1 b)5x10 9 s -1 c)6x10 18 s -1 d)2x10 2 s -1 e)6x10 2 s -1