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Top Document: [sci.astro] General (Astronomy Frequently Asked Questions) (2/9) Previous Document: B.01 What good is astronomy anyway? What has it contributed to society? Next Document: B.03 What new telescopes/instruments are being built? See reader questions & answers on this topic! - Help others by sharing your knowledge William Keel <keel@bildad.astr.ua.edu>, Joseph Lazio <jlazio@patriot.net>, Steve Willner <swillner@cfa.harvard.edu>, Jennifer Imamura The "largest" telescope is a bit difficult to determine. One can obtain many different answers, depending upon the adjectives placed in front of "largest." Nonetheless, what follows is one such list. A list of astronomical instruments is also at <URL:http://www.futureframe.de/astro/instr/index.html>, and a list of large optical telescopes is at <URL:http://www.seds.org/billa/bigeyes.html>. A list of space-based observatories is at <URL:http://www.seds.org/~spider/oaos/oaos.html>. (Optical/Infrared telescopes, nighttime) The list below gives the largest optical telescopes operating today. For complicated pupil shapes, the effective aperture diameter is given. Location is geographic; we omit most organizational details, amusing and intricate as they may be. The list has been truncated at 3 m because there are so many telescopes of that size or smaller. URL's are given where known. Aperture Name Location 10.0 Keck I Mauna Kea, Hawaii (mirror composed of 36 segments) <URL:http://astro.caltech.edu/mirror/keck/index.html> 6.5 Multiple Mirror Mt. Hopkins, Arizona (6 mirrors, 1.8 m each; see also B.03) <URL:http://sculptor.as.arizona.edu/foltz/www/mmt.html> 6.0 BTA Nizhny Arkhyz, Russia (Bolshoi Teleskop Azimutalnyi = Large Altazimuth Telescope) <URL:http://www.sao.ru/> 5.0 Hale Palomar Mountain, California <URL:http://astro.caltech.edu/observatories/palomar/public/index.html> 4.2 William Herschel La Palma, Canary Islands <URL:http://ing.iac.es/WHT.html> 4.0 Victor Blanco Cerro Tololo, Chile <URL:http://www.ctio.noao.edu/4m/base4m.html> 4.0 Mayall Kitt Peak, Arizona <URL:http://www.noao.edu/kpno/kpno.html> 3.9 Anglo-Australian Siding Spring, Australia <URL:http://www.aao.gov.au/> 3.8 UK Infrared Mauna Kea, Hawaii <URL:http://www.jach.hawaii.edu/UKIRT/> 3.6 ESO Cerro La Silla, Chile <URL:http://www.ls.eso.org/> 3.6 Canada-France-Hawaii Mauna Kea, Hawaii <URL:http://www.cfht.hawaii.edu/> 3.5 New Technology Cerro La Silla, Chile <URL:http://www.eso.org/NTT/> 3.5 MPI-CAHA Calar Alto, Spain <URL:http://www.mpia-hd.mpg.de/CAHA/> 3.5 ARC Apache Point, New Mexico (mostly remote control) <URL:http://www.apo.nmsu.edu/> 3.5 WIYN Kitt Peak, Arizona <URL:http://www.noao.edu/wiyn/> 3.5 Starfire Kirtland AFB, New Mexico <URL:http://www.sor.plk.af.mil/default.html> 3.0 Shane Mount Hamilton, California <URL: http://cgi.irving.org/cgi-bin/irving-cgi-bin/xplore.pl?lick+shnentry+A+M > 3.0 NASA IRTF Mauna Kea, Hawaii <URL:http://irtf.ifa.hawaii.edu/> Other telescopes of note: Solar Telescope: Global Oscillation Network Group (GONG), six sites around the world for velocity imaging http://helios.tuc.noao.edu/gonghome.html Largest single dish radio telescope: Arecibo Observatory (Nat. Astron. & Ionosphere Center, Cornell U.) 305-m, Puerto Rico <URL:http://www.naic.edu/> Largest fully-steerable single dish radio telescope: Max Planck Institut fuer Radioastronomie, 100 m, Effelsburg, Germany <URL:http://www.mpifr-bonn.mpg.de/effberg.html> Largest millimeter wave radio telescope: Nobeyama Radio Observatory, 45m, Japan <URL:http://radio.utsunomiya-u.ac.jp/NAO/nobeyama.html> Largest sub-millimeter radio telescope: James Clerk Maxwell Telescope (Joint Astron. Center = UK, Canada, Netherlands), Mauna Kea, 15 m <URL:http://www.jach.hawaii.edu/JCMT/> Largest (connected-element) radio interferometric arrays: Very Large Array (NRAO, New Mexico), 27 dishes, each 26.4 m effective diameter The maximum separation between antennas is ~35 km. <URL:http://www.aoc.nrao.edu/vla/html/VLAhome.shtml> MERLIN (NRAL, University of Manchester, UK) up to 8 dishes, various specifications. The maximum separation between antennae is 217 km (between the Cambridge and Knockin dishes). <URL:http://www.jb.man.ac.uk/merlin/> [MERLIN actually uses radio links between the antenna elements, so maybe it should go into a separate category.] Longest-baseline (dedicated) radio interferometric array: Very Long Baseline Array (NRAO), 10 dishes, each 26.4 m effective diameter, United States. The maximum separation between antennas is ~8600 km, between the islands of St. Croix and Hawaii. <URL:http://www.aoc.nrao.edu/vlba/html/VLBA.html> HALCA (ISAS), 8 m dish, in Earth orbit <URL:http://www.vsop.isas.ac.jp/> Infrared: Infrared Space Observatory (ISO) (ESA) <URL:http://isowww.estec.esa.nl/> Ultraviolet: Extreme Ultraviolet Explorer (EUVE) (NASA) <URL:http://www.cea.berkeley.edu/> International Ultraviolet Explorer (IUE) [defunct] (NASA, PPARC and ESA) <URL:http://www.vilspa.esa.es/iue/iue.html> X-ray: Chandra, the Advanced X-ray Astrophysics Facility (NASA) <URL:http://asc.harvard.edu/> X-Ray Astronomy Satellite (SAX) (ESA) <URL:http://www.sdc.asi.it/> X-Ray Timing Explorer (XTE) (NASA), 2 instruments: PCA & HEXTE <URL:http://heasarc.gsfc.nasa.gov/docs/xte/XTE.html> ASCA/ASTRO-D (ISAS) <URL:http://www.astro.isas.ac.jp/xray/mission/asca/ascaE.html> Roentgen Satellite (ROSAT) (MPE) <URL:http://wave.xray.mpe.mpg.de/rosat/> Einstein, the second High Energy Astronomy Observatory (HEAO-B) [defunct] (NASA), 5 instruments: IPC, HRI, SSS, FPCS, & OGS <URL:http://heasarc.gsfc.nasa.gov/docs/einstein.html> Gamma-ray: Fred Lawrence Whipple Gamma-Ray Observatory (SAO), a 10 m and 11 m instrument <URL:http://linmax.sao.arizona.edu/help/FLWO/whipple.html> CANGAROO (U. Adelaide & Nippon), 4 4-m cameras <URL:http://www.physics.adelaide.edu.au/astrophysics/cangaroo.html> Compton Gamma-Ray Observatory (NASA) [space-based], 4 instruments: OSSE, EGRET, COMPTEL, & BATSE <URL:http://cossc.gsfc.nasa.gov/cossc/cgro.html> Cosmic ray: The High Resolution Fly's Eye Cosmic Ray Detector HiRes <URL:http://www.physics.adelaide.edu.au/astrophysics/FlysEye.html> User Contributions:Comment about this article, ask questions, or add new information about this topic:Top Document: [sci.astro] General (Astronomy Frequently Asked Questions) (2/9) Previous Document: B.01 What good is astronomy anyway? What has it contributed to society? Next Document: B.03 What new telescopes/instruments are being built? Part0 - Part1 - Part2 - Part3 - Part4 - Part5 - Part6 - Part7 - Part8 - Single Page [ Usenet FAQs | Web FAQs | Documents | RFC Index ] Send corrections/additions to the FAQ Maintainer: jlazio@patriot.net
Last Update March 27 2014 @ 02:11 PM
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with stars, then every direction you looked would eventually end on
the surface of a star, and the whole sky would be as bright as the
surface of the Sun.
Why would anyone assume this? Certainly, we have directions where we look that are dark because something that does not emit light (is not a star) is between us and the light. A close example is in our own solar system. When we look at the Sun (a star) during a solar eclipse the Moon blocks the light. When we look at the inner planets of our solar system (Mercury and Venus) as they pass between us and the Sun, do we not get the same effect, i.e. in the direction of the planet we see no light from the Sun? Those planets simply look like dark spots on the Sun.
Olbers' paradox seems to assume that only stars exist in the universe, but what about the planets? Aren't there more planets than stars, thus more obstructions to light than sources of light?
What may be more interesting is why can we see certain stars seemingly continuously. Are there no planets or other obstructions between them and us? Or is the twinkle in stars just caused by the movement of obstructions across the path of light between the stars and us? I was always told the twinkle defines a star while the steady light reflected by our planets defines a planet. Is that because the planets of our solar system don't have the obstructions between Earth and them to cause a twinkle effect?
9-14-2024 KP