named_after hubble deep field
The Jet Propulsion Laboratory ( JPL ) is a federally funded research and development center and NASA field center located in La Cañada Flintridge , ___MASK99___ and Pasadena , ___MASK99___ , United States . A ___MASK84___ ___MASK3___ orbit ( ___MASK13___ ) is an orbit around ___MASK3___ with an altitude between ( orbital period of about 88 minutes ), and ( about 127 minutes ). Objects below approximately will experience very rapid orbital decay and altitude loss . The Hubble Deep Field ___MASK66___ is a composite of several hundred individual images taken using the Hubble Space Telescope ' s Wide Field and Planetary Camera 2 over ___MASK93___ days in September and October 1998 . It followed the great success of the original Hubble Deep Field in facilitating the study of extremely distant galaxies in early stages of their evolution . While the WFPC2 took very deep optical images , nearby fields were simultaneously imaged by the Space Telescope Imaging Spectrograph ( STIS ) and the Near Infrared Camera and Multi - Object Spectrometer ( NICMOS ). An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside of the scope of ___MASK3___ . They look at stars , planets , moons , comets and galaxies , as well as many other celestial objects  either in observational astronomy , in analyzing the data or in theoretical astronomy . Examples of topics or fields astronomers work on include : planetary science , solar astronomy , the origin or evolution of stars , or the formation of galaxies . There are also related but distinct subjects like physical cosmology which studies the Universe as a whole . The Chandra X - ___MASK24___ Observatory ( CXO ), previously known as the Advanced X - ___MASK24___ Astrophysics Facility ( AXAF ), is a Flagship - class space observatory launched on STS - 93 by NASA on July 23 , 1999 . Chandra is sensitive to X - ___MASK24___ sources ___MASK31___ times fainter than any previous X - ___MASK24___ telescope , enabled by the high angular resolution of its mirrors . Since the Earth ' s atmosphere absorbs the vast majority of X - rays , they are not detectable from Earth - based telescopes ; therefore space - based telescopes are required to make these observations . Chandra is an Earth satellite in a 64 - hour orbit , and its mission is ongoing . Amateur astronomy is a hobby whose participants enjoy watching the ___MASK45___ , and the abundance of objects found in it with the unaided ___MASK1___ , binoculars , or telescopes . Even though scientific research is not their ___MASK19___ goal , many amateur astronomers make a contribution to astronomy by monitoring variable stars , tracking asteroids and discovering transient objects , such as comets and novae . The Northern Hemisphere is the half of ___MASK3___ that is north of the equator . For other planets in the Solar System , north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as ___MASK3___ ' s North pole . Due to the ___MASK3___ ' s axial tilt , winter in the Northern Hemisphere lasts from the December solstice ( typically December 21 UTC ) to the March Equinox ( typically March 20 UTC ), while summer lasts from the June solstice ( typically June 21 UTC ) through to the September equinox ( typically September 23 UTC ). The dates vary each year due to the difference between the calendar year and the astronomical year . The Wide Field / Planetary Camera ( WFPC ) ( pronounced as wiffpick ) was a camera installed on the Hubble Space Telescope until December 1993 . It was one of the instruments on Hubble at launch , but its functionality was severely impaired by the defects of the ___MASK19___ mirror optics which afflicted the telescope . However , it produced uniquely valuable high resolution images of relatively bright astronomical objects , allowing for a number of discoveries to be made by HST even in its aberrated condition . Astronomy is a natural science that studies celestial objects and phenomena . It applies ___MASK47___ , physics , and chemistry , in an effort to explain the origin of those objects and phenomena and their evolution . Objects of interest include planets , moons , stars , galaxies , and comets ; while the phenomena include supernovae explosions , gamma ray bursts , and cosmic microwave background radiation . More generally , all astronomical phenomena that originate outside Earth ' s atmosphere are within the purview of astronomy . A related but distinct subject , physical cosmology , is concerned with the study of the Universe as a whole . Polaris , designated Alpha Ursae Minoris ( Ursae Minoris , abbreviated Alpha UMi , UMi ), commonly the ___MASK87___ ___MASK78___ or Pole ___MASK78___ , is the brightest ___MASK78___ in the constellation of Ursa Minor . It is very close to the north celestial pole , making it the current northern pole ___MASK78___ . The revised Hipparcos parallax gives a distance to Polaris of about 433 light - years ( 133 parsecs ), while calculations by other methods derive distances around 30 % closer . The Hubble Deep Field ( HDF ) is an image of a small region in the constellation Ursa Major , constructed from a series of observations by the Hubble Space Telescope . It covers an area ___MASK49___ . ___MASK65___ arcminutes across , about one 24 - millionth of the whole sky , which is equivalent in angular size to a 65 mm tennis ball at a distance of ___MASK31___ metres . The image was assembled from 342 separate exposures taken with the Space Telescope ' s Wide Field and Planetary Camera ___MASK49___ over ten consecutive days between December 18 and December 28 , 1995 . The field is so small that only a few foreground stars in the Milky Way lie within it ; thus , almost all of the 3 , 000 objects in the image are galaxies , some of which are among the youngest and most distant known . By revealing such large numbers of very young galaxies , the HDF has become a landmark image in the study of the early universe , with the associated scientific paper having received over 900 citations by the end of 2014 . Three years after the HDF observations were taken , a region in the south celestial hemisphere was imaged in a similar way and named the Hubble Deep Field South . The similarities between the two regions strengthened the belief that the universe is uniform over large scales and that the Earth occupies a typical region in the Universe ( the cosmological principle ) . A wider but shallower survey was also made as part of the Great Observatories Origins Deep Survey . In 2004 a deeper image , known as the Hubble Ultra - Deep Field ( HUDF ) , was constructed from a few months of light exposure . The HUDF image was at the ___MASK98___ the most sensitive astronomical image ever made at visible wavelengths , and it remained so until the Hubble eXtreme Deep Field ( XDF ) was released in 2012 . A space telescope or space observatory is an instrument located in ___MASK16___ to observe distant planets , galaxies and other astronomical objects . Space telescopes avoid many of the problems of ground - based observatories , such as light pollution and distortion of electromagnetic radiation ( scintillation ). In addition , ultraviolet frequencies , X - rays and gamma rays are blocked by the ___MASK3___ ' s atmosphere , so they can only be observed from space . STS - 125 , or HST - SM4 ( Hubble Space Telescope Servicing Mission ___MASK56___ ), was the fifth and final space shuttle mission to the Hubble Space Telescope ( HST ). The launch of the Space Shuttle " Atlantis " occurred on 11 May 2009 at 2 : 01 pm EDT . Landing occurred on 24 May at 11 : 39 am EDT , with the mission lasting a total of just under 13 days . A tennis ball is a ball designed for the sport of tennis . Tennis balls are fluorescent ___MASK80___ at major sporting events , but in recreational play can be virtually any ___MASK53___ . Tennis balls are covered in a fibrous felt which modifies their aerodynamic properties , and each has a ___MASK94___ curvilinear oval covering it . The National ___MASK23___ and Space Museum of the Smithsonian Institution , also called the NASM , is a museum in Washington , D . ___MASK22___ .. It holds the largest collection of historic aircraft and spacecraft in the world . It was established in 1946 as the National ___MASK23___ Museum and opened its main building on the National Mall near L ' Enfant Plaza in 1976 . In 2014 , the museum saw approximately ___MASK2___ . 7 million visitors , making it the fifth most visited museum in the world . The museum contains the Apollo 11 module , the Friendship 7 which was flown by John Glenn , the Bell X - 1 which broke the sound barrier , and the Wright brothers plane near the entrance . The Wide Field Camera ___MASK76___ ( WFC3 ) is the Hubble Space Telescope ' s last and most technologically advanced instrument to take images in the visible spectrum . It was installed as a replacement for the Wide Field and Planetary Camera 2 during the first spacewalk of Space Shuttle mission STS - 125 on May 14 , 2009 . Felt is a textile that is produced by matting , condensing and pressing fibers together . Felt can be made of natural fibers such as wool , or from synthetic fibers such as ___MASK85___ - based acrylic or acrylonitrile or wood pulp - based rayon . Blended fibers are also common . In modern astronomy , the ___MASK45___ ( celestial ___MASK34___ ) is divided into 88 regions called constellations , generally based on the asterisms ( which are also called " constellations ") of Greek and Roman mythology . Those along the ecliptic are the constellations of the zodiac . Bears are carnivoran mammals of the ___MASK21___ Ursidae . Bears are classified as caniforms , or doglike carnivorans . Although only eight species of bears are extant , they are widespread , appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere . Bears are found on the continents of North America , ___MASK33___ , Europe , and Asia . Common characteristics of modern bears include large bodies with stocky legs , long snouts , small rounded ears , shaggy hair , plantigrade paws with five nonretractile claws , and short tails . A ball is a round object ( usually spherical but sometimes ovoid ) with various uses . It is used in ball games , where the play of the game follows the state of the ball as it is hit , kicked or thrown by players . Balls can also be used for simpler activities , such as catch , marbles and juggling . Balls made from hard - wearing materials are used in engineering applications to provide very ___MASK84___ friction bearings , known as ball bearings . ___MASK38___ - powder weapons use ___MASK67___ and metal balls as projectiles . Ursa Minor ( Latin : " lesser - ___MASK62___ ", contrasting with Ursa Major ), also known as the Little ___MASK62___ , is a constellation in the Northern Sky . Like the Great ___MASK62___ , the tail of the Little ___MASK62___ may also be seen as the handle of a ladle , hence the North American name , Little Dipper : seven stars with four in its bowl like its partner the Big Dipper . It was one of the 48 constellations listed by the 2nd - century astronomer Ptolemy , and remains one of the 88 modern constellations . Ursa Minor has traditionally been important for navigation , particularly by mariners , because of Polaris being the North Star . The Hubble Space Telescope ( HST ) is a space telescope that was launched into ___MASK84___ ___MASK3___ orbit in 1990 , and remains in operation . Although not the first space telescope , Hubble is one of the largest and most versatile , and is well known as both a vital research tool and a public relations boon for astronomy . The HST is named after the astronomer ___MASK60___ , and is one of NASA ' s Great Observatories , along with the Compton Gamma ___MASK24___ Observatory , the Chandra X - ___MASK24___ Observatory , and the Spitzer Space Telescope . ___MASK15___ Ptolemy (" Klaúdios Ptolemaîos ", ; ) was a Greek writer , known as a mathematician , astronomer , geographer , astrologer , and poet of a single epigram in the Greek Anthology . He lived in the city of Alexandria in the Roman province of ___MASK83___ , wrote in Koine Greek , and held Roman citizenship . Beyond that , few reliable details of his life are known . His birthplace has been given as Ptolemais Hermiou in the Thebaid in an uncorroborated statement by the 14th - century astronomer Theodore Meliteniotes . This is a very late attestation , however , and there is no other reason to suppose that he ever lived anywhere else than Alexandria , where he died around AD 168 . The Egg Nebula ( also known as RAFGL 2688 and CRL 2688 ) is a bipolar protoplanetary nebula approximately ___MASK76___ , 000 light - years away from Earth . Its peculiar properties were first described in 1975 using data from the 11 µm survey obtained with sounding rocket by ___MASK23___ Force Geophysical Laboratory ( AFGL ) in 1971 to 1974 . ( Previously , the object was catalogued by ___MASK79___ as a pair of galaxies .) STS - 61 was the first Hubble Space Telescope servicing mission , and the fifth flight of the Space Shuttle " ___MASK72___ ". The mission launched on 2 December 1993 from Kennedy Space Center in Florida . The mission restored the spaceborne observatory ' s vision , marred by spherical aberration , with the installation of a new main camera and a corrective optics package . This correction occurred more than three and a half years after the Hubble was launched aboard STS - 31 in April 1990 . The flight also brought instrument upgrades and new solar arrays to the telescope . With its very heavy workload , the STS - 61 mission was one of the most complex in the Shuttle ' s history . It lasted almost 11 days , and crew members made five spacewalks ( EVAs ), an all - time record . Even the re - positioning of Intelsat VI on STS - 49 in May 1992 required only four . The flight plan allowed for two additional EVAs , which could have raised the total number to seven . The final two contingency EVAs were not made . In order to complete the mission without too much fatigue , the five extravehicular working sessions were shared between two pairs of different astronauts alternating their shifts . The Compton Gamma ___MASK24___ Observatory ( CGRO ) was a space observatory detecting light from 20 keV to 30 GeV in Earth orbit from 1991 to ___MASK28___ . It featured four ___MASK19___ telescopes in one spacecraft , covering X - rays and gamma rays , including various specialized sub - instruments and detectors . Following 14 years of effort , the observatory was launched from Space Shuttle " Atlantis " during STS - 37 on April 5 , 1991 , and operated until its deorbit on June ___MASK56___ , ___MASK28___ . It was deployed in low earth orbit at to avoid the Van Allen radiation belt . It was the heaviest astrophysical payload ever flown at that time at . A constellation is formally defined as a region of the celestial ___MASK34___ , with boundaries laid down by the International Astronomical Union ( IAU ). The constellation areas mostly had their origins in Western - traditional patterns of stars from which the constellations take their names . A ___MASK78___ is a luminous sphere of plasma held together by its own gravity . The nearest ___MASK78___ to Earth is the Sun . Many other stars are visible to the naked eye from Earth during the ___MASK44___ , appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth . Historically , the most prominent stars were grouped into constellations and asterisms , the brightest of which gained proper names . Astronomers have assembled ___MASK78___ catalogues that identify the known stars and provide standardized stellar designations . However , most of the stars in the Universe , including all stars outside our galaxy , the Milky Way , are invisible to the naked eye from Earth . Indeed , most are invisible from Earth even through the most powerful telescopes . Ursa Major ( also known as the Great ___MASK62___ ) is a constellation in the northern celestial hemisphere . One of the 48 constellations listed by Ptolemy ( second century AD ), it remains one of the 88 modern constellations . It can be visible throughout the year in most of the northern hemisphere . Its name , Latin for " the greater ( or larger ) she - ___MASK62___ ", stands as a reference to and in direct contrast with Ursa Minor , " the lesser she - ___MASK62___ ", with which it is frequently associated in mythology and amateur astronomy . The constellation ' s most recognizable asterism , a group of seven relatively bright stars commonly known as the " Big Dipper ", " the Wagon " or " the Plough " ( among others ), both mimics the shape of the lesser ___MASK62___ ( the " Little Dipper ") and is commonly used as a navigational pointer towards the current northern pole star , Polaris in Ursa Minor . The Big Dipper and the constellation as a whole have mythological significance in numerous world cultures , usually as a symbol of the north . The Wide Field and Planetary Camera ___MASK49___ ( WFPC2 ) is a camera formerly installed on the Hubble Space Telescope . The camera was built by the Jet Propulsion Laboratory and is roughly the size of a baby grand piano . It was installed by servicing mission ___MASK10___ ( STS - 61 ) in 1993 , replacing the telescope ' s original Wide Field and Planetary Camera ( WF / PC ). WFPC2 was used to image the Hubble Deep Field in 1995 , the Hourglass Nebula and Egg Nebula in 1996 , and the Hubble Deep Field South in 1998 . During STS - 125 , WFPC2 was removed and replaced with the Wide Field Camera 3 as part of the mission ' s first spacewalk on May 14 , 2009 . After returning to Earth , the camera was displayed briefly at the National Air and Space Museum and the Jet Propulsion Laboratory before returning to its final home at the Smithsonian ' s National Air and Space Museum . In astronomy and navigation , the celestial ___MASK34___ is an imaginary ___MASK34___ of arbitrarily large radius , concentric with ___MASK3___ . All objects in the observer ' s sky can be thought of as projected upon the inside surface of the celestial ___MASK34___ , as if it were the underside of a dome or a hemispherical screen . The celestial ___MASK34___ is a practical tool for spherical astronomy , allowing observers to plot positions of objects in the sky when their distances are unknown or unimportant . Tennis is a racket sport that can be played individually against a single opponent ( singles ) or between two teams of two players each ( doubles ). Each player uses a tennis racket that is strung with cord to strike a hollow ___MASK55___ ball covered with felt over or around a net and into the opponent ' s court . The object of the game is to play the ball in such a way that the opponent is not able to play a valid return . The player who is unable to return the ball will not gain a ___MASK20___ , while the opposite player will . Edwin Powell Hubble ( November 20 , 1889  September 28 , 1953 ) was an American astronomer . He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and is regarded as one of the most important astronomers of all ___MASK98___ . The ___MASK90___ ( NASA ) is an independent agency of the executive branch of the United States federal government responsible for the civilian space program as well as aeronautics and aerospace research .