Searching for the Stars
Cosmic Views and Databases
by David Mattison
Aloha Facts and Image Finders, Victoria, BC
Astronomers have generated a wealth of data about our universe, including some on objects extending beyond visible light. The images seen from the Hubble Space Telescope and famous ground observatories such as the Keck on Mauna Kea, Hawaii, or the Palomar Observatory on Palomar Mountain, Calif., are indeed humbling. The beautiful images are frequently shared and marketed as part of education and outreach programs managed by various observatories and space agencies. This article has gathered the best, most authoritative astronomical image galleries and public databases available.
| Although I don’t own a telescope, I’ve been fascinated by outer space, astronomy, and the prospect of life on other worlds ever since I was a Boy Scout in Hawaii and camped out under the stars far away from the Honolulu city lights.
As remarkable as the achievements of the Space Age have been, the U.S. is still the only nation on Earth which has been able to place human beings on another planetary body and bring them home again, My article looks only at aspects of unmanned space flight that relate to astronomy. While the U.S. space shuttle fleet was used to launch and service the Hubble Space Telescope and other space-based observation instruments, such as the Chandra X-Ray Observatory, that era ended in July 2011 with the final flight of the Endeavour, the last of these remarkable crafts whose life cycles spanned 3 decades (NASA, Space Shuttle Era [http://www.nasa.gov/mission_pages/shuttle/flyout/index.html]). April 2011 marked the 50th anniversary of Soviet cosmonaut Yuri Gagarin’s flight as the first human to orbit Earth. April 2011 saw Global Astronomy Month [http://www.astronomerswithoutborders.org/global-astronomy-month-2011.html] ,a program sponsored by Astronomers Without Borders [http://www.astronomerswithoutborders.org], being celebrated. The theme of 2011’s World Space Week [http://www.worldspaceweek.org], celebrated between Oct. 4 and 10, is “50 Years of Human Spaceflight.” From a photographic perspective, NASA’s visual database The Gateway to Astronaut Photography of Earth [http://eol.jsc.nasa.gov] is an incredible resource and tool.
While amateur astronomers continue to play an important role in the field and are supported by numerous clubs, associations, and their peers, I have primarily examined resources originating from government and academic research environments. To see what the amateurs can do, I suggest you search Google for “amateur astronomy” or look through the amateur astronomy sections of the Yahoo! Directory [http://dir.yahoo.com/science/astronomy/Amateur_Astronomy] and the Google Directory [http://www.google.com/Top/Science/Astronomy/Amateur]. You will find thousands of useful leads. One notable example provides a free service to amateur astronomers that lets them post their images. The Astronomical Image Data Archive (AIDA) [http://aida.astroinfo.org] contains more than 4,000 images. The host site, AstroInfo, is based in Switzerland.
From its historical roots through discoveries with optical (visible light) telescopes, today’s scientific successors to Johannes Kepler, Tycho Brahe, and Galileo Galilei use ground and space observatories with instruments that detect and capture data right across the electromagnetic spectrum: radio, microwave, infrared, visible light, ultraviolet, X-rays, and gamma rays. Since our eyes can only see a small range within the spectrum, different kinds of data are often combined and manipulated through computer processing to provide new and unique perspectives and discoveries about the universe. The international astronomy community has also developed its own image file format called FITS (Flexible Image Transport System) [http://fits.gsfc.nasa.gov and http://en.wikipedia.org/wiki/FITS].
The Real Armchair World of Virtual Astronomy
The internet has helped shape and redefine the scope and nature of the research tools and data available to astronomers. In his article “ Virtual Astronomy, Information Technology, and the New Scientific Methodology” (2005) [http://www.astro.caltech.edu/~george/vo/VAITNSM.pdf], S. G. Djorgovski described the Virtual Observatory as “an emerging, open, web-based, distributed research environment for astronomy with massive and complex data sets. It assembles data archives and services, as well as data exploration and analysis tools.”
In terms of astronomical images, the international Virtual Astronomy Multimedia Project (VAMP) [http://www.virtualastronomy.org], according to its project description, “will allow observatories and others to ingest any future resource that conforms to the suggested standards and make them immediately searchable. The primary deliverable of VAMP is a database server that indexes, searches, and serves out standardized metadata and education/public outreach image file locations of the world’s research observatories and telescopes. VAMP will utilize the International Virtual Observatory Alliance (IVOA) endorsed outreach metadata standard, Astronomical Visualization Metadata 1.0 (AVM) and help support observatories in adopting and adhering to these standards” [http://www.virtualastronomy.org/07-10-24VAMP.pdf].
The U.S. Virtual Astronomical Observatory (VAO) [http://www.usvao.org], formerly the National Virtual Observatory (NVO) [http://www.us-vo.org], is one of a network of several such tools that would not exist without the internet and the efforts of the International Virtual Observatory Alliance (IVOA) [http://www.ivoa.net]. The main purpose of these virtual observatories is to collate the massive amounts of data and images from multiple sources for any given point in the sky. Two prominent tools for this purpose are NASA’s DataScope [http://heasarc.gsfc.nasa.gov/cgi-bin/vo/datascope/init.pl] and the Centre de Données astronomiques de Strasbourg’s Aladin SkyAtlas [http://aladin.u-strasbg.fr]. The Sky ViewVirtual Observatory [http://skyview.gsfc.nasa.gov], somewhat similar to Aladin, includes a Non-Astronomer’s Page on how best to utilize the many options on the Query Form page.
Launched in May 2008 in a public beta version, you can engage with Microsoft Research and NASA’s WorldWide Telescope (WWT) [http://www.worldwidetelescope.org] in two ways: through its web interface or through Windows client software that you download and install on your PC. According to its About page, “WWT blends terabytes of images, information, and stories from multiple sources into a seamless, immersive, rich media experience delivered over the Internet” [http://www.worldwidetelescope.org/WhatIs/WhatisWWT.aspx]. Perhaps one day you might become one of many WWT Ambassadors “trained to be experts in using WWT as a teaching tool” [https://wwtambassadors.org/wwt].
Created by Konstantin Lysenko and Sergei Goshko, based in Canada, and launched late in 2006, Sky-Map [http://www.sky-map.org], also known as WikiSky [http://wikisky.org], is a comparable tool to the WWT, though not as well-endowed financially. A major difference from WWT is that Sky-Map only references objects outside the solar system. Both Sky-Map and the WWT utilize the Sloan Digital Sky Survey as well as data from other sky surveys.
The cross-platform Google Earth software [http://earth.google.com] contains a separate Sky database based on content from, among other sources, the Sloan Digital Sky Survey, the Digitized Sky Survey, and the Space Telescope Science Institute (the Hubble). The Google service presents all the sources within the context of the constellations and other well-known individual stars and planets. Sky contains a number of other astronomy-related services, one of the most ambitious of which is the SLOOH Space Camera [http://www.slooh.com], a subscription-based ground observatory, through which members help document the universe and witness live astronomical events.
I tried out the Windows 0.10.6 version of the free, open source, cross-platform Stellarium planetarium software [http://www.stellarium.org]. According to the FAQ on the project wiki, Stellarium was started in 2001 by Fabien Chéreau. The PDF manual alone is worth downloading for its explanation of astronomical concepts. The European Southern Observatory’s VirGO software [http://archive.eso.org/cms/tools-documentation/visual-archive-browser] contains an earlier release of Stellarium packaged with the functionality to allow you to examine imagery and other data from the ESO and other observatories’ archives.
There are two basic classes of ground-based astronomical observatories, those that rely on optical telescopes and those that depend on nonoptical data such as radio and microwaves. Optical telescopes rely on a combination of mirrors, lenses, and sensing instruments to utilize various parts of the electromagnetic spectrum in order to see into deep space. Some observatories combine both types of technologies, while others, such as the famous Arecibo Observatory in Puerto Rico [http://www.naic.edu], are exclusively devoted to monitoring, radio waves, for example. Both kinds of observatories monitor our solar system as well as objects light-years distant.
In the U.S., optical ground observatories that operate at night are under the domain of the National Optical Astronomy Observatory (NOAO) [http://www.noao.edu], managed for the National Science Foundation (NSF) by the Association of Universities for Research in Astronomy. Among the well-known telescopes within the NOAO are the Kitt Peak National Observatory in Arizona [http://www.noao.edu/kpno], home to “the world’s largest collection of optical telescopes” [http://www.noao.edu/outreach/kpoutreach.html], and the twin, multinational Gemini Observatory telescopes in Hawaii and Chile [http://www.gemini.edu]. The umbrella of NOAO also covers the National Solar Observatory [http://www.nso.edu], devoted to the study of our own star and currently searching for a new headquarters. The NOAO Image Gallery [http://www.noao.edu/image_gallery], with a controlled vocabulary and free-text search engine geared to the general public, contains a few hundred contributions from all its telescopes as well as links to some of the other image galleries I’ve described.
The National Radio Astronomy Observatory [http://www.nrao.edu], a similar umbrella organization operated by the NSF, offers a small Image Gallery [http://images.nrao.edu] of around 200 items based on its observational technologies. Radio telescopes such as Arecibo consist of one or more dish-shaped antenna assemblies. The newest such international radio telescope array, sited in Chile and still under construction as of spring 2011, is called ALMA (Atacama Large Millimeter/submillimeter Array) [http://www.almaobservatory.org]. One of its main purposes is to reach back in time, as all deep space observatories do, to uncover clues about the formation of the universe through the currently accepted scientific model of the Big Bang.
The Australian Astronomical Observatory (AAO) has a fine collection of Astronomical Images [http://www.aao.gov.au/images/index.html], including more than 400 galaxies, galactic clusters, and nebulae. The page of 50 Favorite AAO Photographs [http://www.aao.gov.au/images/general/favourites.html] highlights some of the most extraordinary, beautiful, and recognizable starscapes out there such as the Horsehead and Crab nebulae. Most of these photographs were created through a process developed by David Malin, an astronomer who worked at the AAO until 2001 and subsequently established his own business.
The European Southern Observatory [http://www.eso.org] features an impressive gallery of imagery, not all of the sky and with some artist impressions, including a Picture of the Week [http://www.eso.org/public/images/potw] dating back to 2007, more than 1,400 zoomable images [http://www.eso.org/public/images/archive/zoomable], and more than 4,900 wallpaper images for your computer screen [http://www.eso.org/public/images/archive/wallpapers]. You may recognize the ESO’s Paranal Observatory in Chile from the James Bond movie Quantum of Solace.
Image Collections From Space Telescopes
NASA’s Hubble Space Telescope [http://hubblesite.org], launched in 1990 and the most well-known telescope operating beyond Earth’s atmosphere, is not the only orbiting observatory. In addition to the science and imagery from this amazing instrument, HubbleSite also features useful astronomy reference resources and tools such as the gSky Browser [http://hubblesite.org/explore_astronomy/gsky]. This customized browser lets you use the Google Earth application [http://earth.google.com] to study the universe through Hubble’s images. On May 15, 2011, the HubbleSite Gallery contained 1,209 images covering deep space objects and our solar system. Up to four image file resolution downloads may be available, along with links to all other images of the same object and to the NewsCenter’s commentary about the image. The full spectrum of publicly released Hubble data is accessible through the Hubble Legacy Archive [http://hla.stsci.edu]; Data Release 5 occurred in March 2011. The successor to Hubble, the tennis-court-sized James Webb Space Telescope [http://webbtelescope.org], is scheduled to launch post-2015 and will be stationed a million miles from Earth. A ground-based optical and infrared telescope which will complement the Webb space telescope, currently called the Thirty Meter Telescope [http://www.tmt.org], a joint American-Canadian university initiative, is scheduled to receive “first light” in 2017 or 2018 from its site atop the Mauna Kea volcano in Hawaii. It is expected to become “the most advanced and powerful optical telescope on Earth” [http://www.tmt.org/about-tmt].
Other orbiting telescopes and satellites with deep space image collections include the NASA Spitzer Space Telescope [http://www.spitzer.caltech.edu/images], launched in 2003 and also tasked in the search for exoplanets (planets outside our solar system) via infrared wavelength, its primary instrumentation. The NASA Kepler [http://kepler.nasa.gov/media], launched in March 2009, is also hunting for exoplanets, as is EPOCh [http://epoxi.umd.edu/4gallery/index.shtml], a repurposed 2005 Deep Impact satellite also known as EPOXI. EPOCh, along with the Kepler, uses the transit method for the exoplanet search. CoRoT (Convection, Rotation and planetary Transits) [http://smsc.cnes.fr/COROT], launched in December 2006 by France’s CNES, is likewise looking for planets via the transit method. It made its first detection of Corot-Exo-1b (CoRoT-1 b) in 2007. The CoRoT Data Center at the Institut d’Astrophysique Spatiale (IAS) contains links to restricted and open access databases chiefly designed for the scientific community [http://idoc-corot.ias.u-psud.fr].
Three other NASA space telescopes are also observing in nonvisible light: the Compton Gamma-Ray Observatory (CGRO) [http://heasarc.gsfc.nasa.gov/docs/cgro], whose mission lasted between 1991 and 2000, and the Chandra X-Ray Observatory (CXO) [http://chandra.harvard.edu], launched in 1999. Chandra, operated for NASA by the Smithsonian Astrophysical Observatory (SAO), documents its many impressive observations through a Photo Album page [http://chandra.harvard.edu/photo]. It also features some interactive tools such as a 3D Wall, the Chandra Sky Map, and tutorials to further explore these unusual images. Some of the data gathered by Chandra has also been combined with those of other space observatories such as Spitzer. GALEX, the Galaxy Evolution Explorer [http://www.galex.caltech.edu], launched in 2003, is studying the evolution of galaxies utilizing ultraviolet radiation. One of its most spectacular discoveries from 2006 was the 13-light-year tail of the fast-moving red giant star Mira.
While I thought the debate had long been settled about the clarity of images between ground- and space-based optical telescopes (in favor of the latter), the multinational research institution consortium building the Giant Magellean Telescope [http://www.gmto.org] claims that its instrument, “primary mirror — far larger than any other telescope ever built … will produce images up to 10 times sharper than the Hubble Space Telescope.” You’ll be able to check this yourself around 2018 when the telescope is completed on a peak at Las Campanas, Chile.
Space Images From Space Agencies
The world’s space agencies maintain enormous collections of space imagery. In particular, NASA maintains still and video images at NASA Images [http://www.nasaimages.org]. The site is “a partnership between NASA and the Internet Archive … to bring public access to NASA’s image, video, and audio collections in a single, searchable resource” [http://www.nasaimages.org/About.html]. I searched all collections for the term “NASA”and retrieved 100,000 items, likely some kind of default maximum number of results. The primary search points are content category thumbnails and keyword search field. Once you’ve retrieved some results through either method, you can refine your search through four filters (What, Where, Who, When) or by selecting the Advanced Search link. You can also browse through category lists or “alphanumerically” (indexed keywords and numerical content such as dates). By registering for a free account, you can also create presentations and your own personalized content. For more current NASA imagery, visit NASA’s main site [http://www.nasa.gov], where you will find a Multimedia link as well as an Image Gallery one [http://www.nasa.gov/multimedia/imagegallery].
NASA also dishes up the Astronomy Picture of the Day [http://apod.nasa.gov/apod; http://apod.nasa.gov/apod/lib/aptree.html] from its vast reservoir of imagery. Each image is accompanied by a commentary from a professional astronomer. You can keyword-search for images or simply consult a chronological list (the Calendar link) dating back to June 16, 1995.
NASA’s National Space Science Data Center (NSSDC), “the permanent archive for NASA space science mission data” [http://nssdc.gsfc.nasa.gov/about/about_nssdc.html], is another nexus for NASA imagery. The primary access point is its Image Resources section [http://nssdc.gsfc.nasa.gov/image], from which you can jump to the NSSDC Photo Gallery [http://nssdc.gsfc.nasa.gov/photo_gallery] and its Catalog of Spaceborne Imaging: A Guide to NSSDC’s Planetary Image Archives [http://nssdc.gsfc.nasa.gov/imgcat]. Since NSSDC is an archive, as you’d expect, the imagery comes from historic spaceflight, robotic, satellite, and space telescope observations. Another source for imagery from the various robotic and satellite craft sent to other planets in our solar system is the Planetary Data System (PDS) [http://pds.jpl.nasa.gov], which “archives and distributes scientific data from NASA planetary missions, astronomical observations, and laboratory measurements” [http://pds.jpl.nasa.gov]. You can search for images through the PDS Imaging Node [http://pds-imaging.jpl.nasa.gov]. Through a complementary site operated by the U.S. Geological Survey, you can also Map-a-Planet [http://www.mapaplanet.org] using PDS data.
Another important NASA site for astronomical imagery, based on “extremely energetic phenomena, from black holes to the Big Bang,” is the High Energy Astrophysics Science Archive Research Center (HEASARC) [http://heasarc.gsfc.nasa.gov], housed at the Goddard Space Flight Center in Maryland. HEASARC images are derived from NASA and other agency space telescopes with observations by X-ray, extreme-ultraviolet, and gamma-ray spectra made for more than 3 decades. HEASARC contains a large number of image-based resources for students and the public such as the HEASARC Picture of the Week [http://heasarc.gsfc.nasa.gov/docs/objects/heapow] and its archive [http://heasarc.gsfc.nasa.gov/docs/objects/heapow/archive/heapow_archive.html], an Image Archive [http://heasarc.gsfc.nasa.gov/docs/objects], and, to put things in perspective, a tutorial about The Cosmic Distance Scale [http://heasarc.gsfc.nasa.gov/docs/cosmic].
The Jet Propulsion Laboratory (JPL) at the California Institute of Technology provides a wealth of imagery through its Multimedia page [http://www.jpl.nasa.gov/multimedia/index.cfm), with links to other sites. The Photojournal [http://photojournal.jpl.nasa.gov] site, for example, also contains a flexible and friendly database to JPL and imagery gathered from other sources and jurisdictions. The imagery content of the Photojournal, arranged into galleries, consists of the solar system, the universe beyond our system, and spacecraft and telescopes. Each gallery may contain anywhere from a handful to a few hundred images.
By May 15, 2011, the European Space Agency (ESA) Multimedia Gallery [http://www.esa.int/esa-mmg/mmghome.pl] featured more than 9,600 items, with about a third of that content consisting of satellite imagery of Earth and astronomical observations. Searches of the ESA image content is conducted through controlled vocabulary lists or keywords. The Advanced Search lets you combine a controlled vocabulary search with a keyword search. You’ll also find a handy link to the National Galleries [http://esamultimedia.esa.int/multimedia/nationalgallery/index.html] of other European and Canadian national space agencies.
Like NASA, the ESA maintains dedicated sites to specific space telescopes, and content may not necessarily appear in both the dedicated site and the Multimedia Gallery. For example, the ESA site for its Herschel space telescope’s images and videos yields 498 items [http://sci.esa.int/science-e/www/area/index.cfm?fareaid=16], while the Multimedia Gallery’s Advanced Search for all content relating to the Herschel Mission retrieved less than half those items, or 210 results. You can access images and videos of all the ESA past, current, and planned satellite and space observatory projects through the Missions link on its Science and Technology (Science Programme) site [http://sci.esa.int/science-e/www/area/index.cfm?fareaid=1].
If you’re ever curious about what kinds of objects have been launched into space and what’s happened to them, the United Nations Office for Outer Space Affairs (UNOOSA), established in 1958, maintains an Online Index of Objects Launched Into Outer Space [http://www.unoosa.org/oosa/osoindex.html]. It carries “information on satellites launched from 1957 to the present. Space debris and other non-functional objects are not included.” The data comes from the “World Warning Agency for Satellites, Committee on Space Research (COSPAR), official press releases and media sources.” Heavens Above [http://www.heavens-above.com], created and maintained by Chris Peat, is a somewhat comparable, privately operated site that covers astronomical events, objects, and ephemeris and provides predictive locations for orbiting satellites and the International Space Station.
Catalogs, Surveys, and Databases to the Heavens
Astronomers deal with such massive volumes of data that I’m not surprised they have well-developed systems for organizing and retrieving information about the objects they and their scientific ancestors have been observing for centuries. Individual celestial objects outside our solar system are documented in star catalogs; more than 9,000 such catalogs are available online through the Centre de Données astron omiques de Strasbourg’s VizieR’s service. Another systematic technique used by astronomers is sky surveys, which form the backdrop for some of the virtual astronomy applications.
The first systematic astronomical observation compilation of its kind, you’ll find various versions of the Messier Catalog on the web, Named after its compiler, the 18th-century French astronomer Charles Messier (1730–1817), the thoroughly documented site covers his list of 110 nebulae and star clusters observed from Paris. The Messier Catalog was created by the Students for the Exploration and Development of Space (SEDS) [http://www.seds.org/messier]. The SEDS group has also created many other useful resources based on historical astronomical data.
In the century following Messier’s work, other astronomers, such as England’s William Herschel and Australia’s James Dunlop, were influenced by his example. These astronomers created their own catalogs of deep sky objects. The culmination and standardization of all this work arrived in 1888 with the publication by Danish astronomer J.L.E. Dreyer (1852–1926) of New General Catalogue of Nebulae and Clusters of Stars. This title was abbreviated to NGC or NGC/IC after the supplemental Index Catalogues he issued. At the time Dreyer was working at the Armagh Observatory in Ireland; he later undertook to publish the work of his scientific ancestor Tycho Brahe (1546–1601).
The best web overview and resource on the NGC/IC, the aptly named The NGC/IC Project [http://www.ngcicproject.org], also includes its own version of the Messier Catalog and other historic observational lists, as well as more current catalogs submitted by other astronomers. The mission of The NGC/IC Project is “to correctly identify all of the original NGC and IC objects, starting with the original discoverer’s notes and working forward in time to encompass the work of contemporary astronomers, both professional and amateur …” [http://www.ngcicproject.org/mission.htm].
SEDS also maintains The Interactive NGC Catalog Online [http://spider.seds.org/ngc/ngc.html], based on NGC 2000.0 by R.W. Sinnott (Sky Publishing), with links to various other catalogs and databases, including the massive NASA/IPAC Extragalactic Database (NED) [http://ned.ipac.caltech.edu]. The latter “contains positions, basic data, and over 171 million names for 163 million extragalactic objects, as well as more than 6,100,000 bibliographic references to over 76,500 published papers, and 66,700 notes from catalogs and other publications” [http://ned.ipac.caltech.edu/help/allfeats.html]. Images are retrieved by either object name or through the NED Image Data Atlas [http://irsa.ipac.caltech.edu/data/NED].
The Centre de Données astronomiques de Strasbourg in France maintains three essential astronomy databases: SIMBAD [http://simbad.u-strasbg.fr/simbad], an “astronomical database [that] provides basic data, cross-identifications, bibliography and measurements for astronomical objects outside the solar system”; the AladinSky Atlas [http://aladin.u-strasbg.fr], a Java-based sky atlas linked to SIMBAD records which you can also download for local installation; and VizieR [http://cdsarc.u-strasbg.fr/viz-bin/VizieR], a bibliographic database of more than 9,000 online published astronomical catalogs and data, with individual entry points linked to Aladin content.
You can access archived data from ground and space optical and radio observatories through MAST, the Multimission Archive at STScI [http://archive.stsci.edu], “with a primary focus on scientifically related data sets in the optical, ultraviolet, and near-infrared parts of the spectrum.” MAST offers a variety of search strategies, including cross-mission (cross-correlation) as well as mission-specific searches. Selecting image types on the basic search page is as simple as checking a box. You can preview images as either a GIF or a FITS (Flexible Image Transport System) image.
The Sloan Digital Sky Survey [http://www.sdss.org], operating since 2000, calls itself “one of the most ambitious and influential surveys in the history of astronomy. … it obtained deep, multi-color images covering more than a quarter of the sky and created 3-dimensional maps containing more than 930,000 galaxies and more than 120,000 quasars.” Data, gathered from a telescope at the Apache Point Observatory, New Mexico, is released annually, and you can query or browse through the images using a variety of tools at the multilingual SDSS SkyServer sites (http://cas.sdss.org for the public and http://cas.sdss.org/astro for professional astronomers).
The Digitized Sky Survey [http://stdatu.stsci.edu/dss], the first version of which appeared in 1994, is based on digitized photographic plates created by the Space Telescope Science Institute from observations at the California Institute of Technology’s Palomar Observatory (Palomar Astronomical Images) [http://www.astro.caltech.edu/palomar/astrophotos.html] and the UK Schmidt Telescope in Australia. Data from these observatories was also used to create the first Guide Star Catalog for the Hubble Space Telescope. You’ll find a link here to a few other DSS sites, each with its version, sometimes with additional data, of the source imagery. The DSS is also only one of several resources available for searching within the Multimission Archive at STScI or MAST [http://stdatu.stsci.edu].
The 2MASS Atlas Image Gallery at IPAC [http://www.ipac.caltech.edu/2mass/gallery] contains processed images from the Two Micron All Sky Survey, a 1997–2001 joint project of the University of Massachusetts and the Infrared Processing and Analysis Center, California Institute of Technology, which mapped nearly all the Northern and Southern Hemisphere skies through ground-based observatories in infrared. The 2MASS images are one of the data sets at the NASA/IPAC Infrared Science Archive [http://irsa.ipac.caltech.edu], where you’ll find various kinds of tools for querying. Cool Cosmos [http://coolcosmos.ipac.caltech.edu], an award-winning education and outreach site from the California Institute of Technology’s Infrared Processing and Analysis Center (IPAC), features excellent image galleries on infrared and multi-wavelength astronomy. IPAC also maintains a Gallery of images [http://www.ipac.caltech.edu/gallery] from several space telescopes, such as Spitzer and Herschel.
I found the Hawaiian Astronomical Society’s Constellations: Stories and a Deepsky Atlas [http://www.hawastsoc.org/deepsky] one of the more unusual and useful tools. It provided me with an easy way to use this “online atlas of the heavens, combined with photographs of significant objects, and their descriptions,” that is, stories or myths and information about the constellations and other deep sky objects between 45 degrees latitude north of the equator and 45 degrees latitude south of the equator based on any month and time. You can print a version of any of the maps for field observation. Obviously this site has limited use for those of us living north or south of those latitudes.
The Planet Hunters
NASA’s PlanetQuest: Exoplanet Exploration [http://planetquest.jpl.nasa.gov], located at the Jet Propulsion Laboratory, California Institute of Technology, is among the best sources of information for the general public on the search for an Earth-like world. While I was researching and writing this article, the discovery by a Canadian space telescope of yet another “super-Earth” planet, called 55 Cancri e, was announced (“Tiny space telescope reveals ‘super-Earth,’” Vancouver Sun, April 29, 2011 [http://www.vancouversun.com/technology/Tiny+space+telescope+reveals+super+Earth/4694986/story.html]).
Included among these truly far-out exoplanet detection, research, and dissemination efforts are the following:
•NStED [http://nsted.ipac.caltech.edu], the NASA/IPAC/NExScI Star and Exoplanet Database, is the most reliable and comprehensive database for information on exoplanets. In between April 15 and May 15, 2011, the number of such planets went from 531 to 535, and the number of planet-hosting stars grew from 444 to 448. According to the Overview page, “All data in NStED are vetted by a team of astronomers and are linked back to the original literature reference. Data are searchable either for an individual star or by stellar and planetary properties. NStED also offers direct access to frequently accessed tables, including [a] list of all known planets [and a] list of all known planet-hosting stars” [http://nsted.ipac.caltech.edu/NStED/docs/intro.html].
•NExScI or the NASA Exoplanet Science Institute [http://nexsci.caltech.edu] at the California Institute of Technology is the command and control center for NASA’s exoplanet research program. In addition to helping administer the NtSED database, NExScI also manages NASA’s time slice of the W.M. Keck Observatory [http://www.keckobservatory.org] on the summit of Mauna Kea, Hawaii.
• The Extrasolar Planets Encyclopaedia [http://exoplanet.eu], created in 1995 and currently maintained by Jean Schneider, CNRS-LUTH (Centre national de la recherche scientifique, Laboratoire Univers et Théories), Paris Observatory, offers through its interactive catalog a wealth of data and explanations about planets orbiting other stars which have been discovered by space observatories such as Kepler and CoRoT. I was impressed by the list of ongoing and projected ground- and space-based searches for exoplanets.
• The University of California spearheads the California Planet Survey [http://exoplanets.org/cps]. Users can query and view data through its Expoplanet Data Explorer [http://exoplanets.org/index.html]. Since 1995, this research team has “discovered 115 Jupiter-like and Saturn-like planets orbiting nearby stars.”
• The Anglo-Australian Planet Search [http://www.phys.unsw.edu.au/~cgt/planet/AAPS_Home.html] uses a telescope at Siding Spring, New South Wales, to search for gas-giant planets similar to Jupiter and Saturn and establishes their existence through a technique called “Doppler wobble.” The group announced its first exoplanet discovery in November 1999 and has more than 240 nearby sunlike stars to search. It claims to have achieved “the highest long-term precision demonstrated by any Southern Hemisphere planet search.”
• As its name implies, the Exoplanet Transit Database (ETD) [http://var.astro.cz/ETD], operated by the Czech Astronomical Society’s Variable Star and Exoplanet Section, is strictly devoted to planetary bodies discovered through the transit method. As of May 15, 2011, ETD documents 122 such observations, the earliest from 1997.
• A number of robotic telescopes specifically designed to hunt for transiting planets have been hard at work. One of the most recent to come online was TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) in Chile, which released its first test observations in 2010; it is controlled from a station in Belgium as part of the European Southern Observatory [http://www.eso.org].
• Taking a page from the SETI@home (Search for Extraterrestrial Life) [http://setiathome.berkeley.edu] program and similar “citizen science” projects, PlanetHunters.org [http://www.planethunters.org] is a collaboration between Yale University and the Zooniverse [http://www.zooniverse.org]. It provides you and your computer with an opportunity to assist in the analysis of data from the Kepler space telescope. As of May 15, 2011, according to the Planetometer [http://www.planethunters.org/planetometer], 2,913,458 observations have been analyzed and 69 potential planets identified. Maybe you will find the next exoplanet!
A Constellation of Astronomy Organizations and Periodicals
Based in Paris, the International Astronomical Union (IAU) [http://www.iau.org] was created in 1919. Today, its “mission is to promote and safeguard the science of astronomy in all its aspects through international cooperation.” Members are professional astronomers with at least a Ph.D. As part of its promotional endeavors, the IAU site includes a section on Astronomy for the Public [http://www.iau.org/public] that covers trendy and enduring topics such as “Buying Stars and Star Names” (you’d be wasting your money) and “Careers in Astronomy.” The IAU and the United Nations Educational, Scientific, and Cultural Organization (UNESCO) also co-sponsored the International Year of Astronomy 2009 [http://www.astronomy2009.org].
The American Astronomical Society (AAS) [http://aas.org] was established in 1899 and boasts around 7,000 members. The society publishes four journals. The Education Services section features a general introduction to astronomy, annotated resource links for educators and students, and general links.
Among the several English-language publications devoted to astronomy, I found these to offer a wealth of online resources:
Astronomy [http://www.astronomy.com] features a Java applet called StarDome, which lets you track throughout the day and night the position of the sun, planets, and other astronomical objects. Magazine subscribers get a better version plus access to an interactive version of the magazine’s Star Atlas. The News and Observing section provides an array of helpful information, such as The Sky This Week, The Sky This Month, a glossary, an introduction to astronomy, and tips for photographing the night sky.
Sky & Telescope [http://www.skyandtelescope.com] bills itself as the “essential magazine of astronomy.” You’ll find an Interactive Sky Chart here along with several other online tools to make the most of your viewing time.
Australian Sky & Telescope [http://www.austskyandtel.com.au] is the somewhat equivalent edition for stargazers Down Under.
Astronomy Now [http://www.astronomynow.com] is a British publication with an Interactive Sky Chart, a weekly night sky guide, and a planetary calculator all keyed to the British Isles.
Sky at Night Magazine [http://www.skyatnightmagazine.com] is another British publication, this one produced by the BBC.
Terence Dickinson’s SkyNews [http://www.skynews.ca] is named after the founding editor, who is still there, and described as “Canada’s leading author of astronomy books for both adults and children.” The Resources section focuses on amateur observing and public education about astronomy. If you’d like to know your chances of seeing an aurora, check out the Aurora Watch that’s updated daily via the NOAA Space Weather Prediction Center [http://www.swpc.noaa.gov]. The Canadian government also maintains its own Space Weather Canada watch [http://www.spaceweather.gc.ca].
Other magazines devoted to the amateur astronomer are the Amateur Astronomy Magazine [http://www.amateurastronomy.com], “written by amateur astronomers, for amateur astronomers” and published for nearly 2 decades; The Astronomer [http://www.theastronomer.org], marketed to the “advanced amateur” and published since May 1964; the more recent Practical Astronomer Magazine [http://practicalastronomy.com], a British publication founded in 2009 and distributed for free online.