{ "count": 5, "next": null, "previous": null, "results": [ { "id": 4041, "url": "https://svs.gsfc.nasa.gov/4041/", "result_type": "Visualization", "release_date": "2013-02-08T00:00:00-05:00", "title": "GRAIL Free-Air Gravity Map for the Cover of Science", "description": "These print-resolution stills were created for the cover of the February 8, 2013 issue of Science. They show the free-air gravity map developed by the Gravity Recovery and Interior Laboratory (GRAIL) mission.If the Moon were a perfectly smooth sphere of uniform density, the gravity map would be a single, featureless color, indicating that the force of gravity at a given elevation was the same everywhere. But like other rocky bodies in the solar system, including Earth, the Moon has both a bumpy surface and a lumpy interior. Spacecraft in orbit around the Moon experience slight variations in gravity caused by both of these irregularities.The free-air gravity map shows deviations from the mean, the gravity that a cueball Moon would have. The deviations are measured in milliGals, a unit of acceleration. On the map, dark purple is at the low end of the range, at around -400 mGals, and red is at the high end near +400 mGals. Yellow denotes the mean.These views show a part of the Moon's surface that's never visible from Earth. They are centered on lunar coordinates 29°N 142°E. The large, multi-ringed impact feature near the center is Mare Moscoviense. The crater Mendeleev is south of this. The digital elevation model for the terrain is from the Lunar Reconnaissance Orbiter laser altimeter (LOLA). Merely for plausibility, the sun angle and starry background are accurate for specific dates (December 21, 2012, 0:00 UT and January 8, 2013, 14:00 UT, respectively). || ", "hits": 134 }, { "id": 3895, "url": "https://svs.gsfc.nasa.gov/3895/", "result_type": "Visualization", "release_date": "2012-01-17T00:00:00-05:00", "title": "Deep Star Maps", "description": "This set of star maps was created by plotting the position, brightness, and color of just over 100 million stars from the Bright Star, Tycho-2, and UCAC3 star catalogs. The constellation boundaries are those established by the International Astronomical Union in 1930. The constellation figures also come from the IAU, although they're not official.The maps are presented in plate carrée projections using either celestial (J2000 geocentric right ascension and declination) or galactic coordinates. They are designed for spherical mapping in animation software. The oval shapes near the top and bottom of the star maps are not galaxies. The distortion of the stars in those parts of the map is just an effect of the projection.The celestial coordinate mapping will be the more useful one for animation, since camera rotations in the software will correspond in a straightforward way to the right ascension and declination in astronomy references. The galactic coordinate mapping works as a standalone image showing the edge-on view of our home galaxy, from the inside.The animation demonstrates the use of the maps in a tour of the sky. The tour starts at W-shaped Cassiopeia, then heads south through Perseus to the winter constellation of Orion the Hunter and the Hyades and Pleiades star clusters in Taurus. It moves southeast past Orion's canine companion and its star, Sirius, brightest in the sky, eventually pausing at the rich southern hemisphere portion of the Milky Way in Carina and Crux, the Southern Cross.East of the Cross, in Centaurus, is the binary star Alpha Centauri, at 4.4 light-years the naked-eye star system nearest to the Sun. Also visible as a fuzzy spot near the top of the frame is the globular cluster Omega Centauri. The number of stars used to draw the star maps is large enough to reveal many globular and open star clusters as well as the Large and Small Magellanic Clouds.After passing near the celestial south pole, the tour moves north along the Milky Way to the center of our galaxy near the teapot in Sagittarius. The tour veers northwest from there, finally stopping at the familiar Big Dipper or Plough asterism in Ursa Major.This is an update to entry 3572. || ", "hits": 1151 }, { "id": 78, "url": "https://svs.gsfc.nasa.gov/78/", "result_type": "Visualization", "release_date": "1995-05-26T12:00:00-04:00", "title": "Ocean Planet: Final Version with Credits", "description": "The Ocean Planet is a traveling exhibition from the Smithsonian Institution which opened in Washington DC on April 22, 1995. A part of the exhibition was a computer flyby of the Pacific Ocean developed in the SVS. This animation represents a stage in the development of that flyby. || ", "hits": 52 }, { "id": 58, "url": "https://svs.gsfc.nasa.gov/58/", "result_type": "Visualization", "release_date": "1994-04-29T12:00:00-04:00", "title": "Ocean Planet: Partial Tour with Map Route Inset", "description": "The Ocean Planet is a traveling exhibition from the Smithsonian Institution which opened in Washington DC on April 22, 1995. A part of the exhibition was a computer flyby of the Pacific Ocean developed in the SVS. This animation represents a stage in the development of that flyby. || ", "hits": 52 }, { "id": 59, "url": "https://svs.gsfc.nasa.gov/59/", "result_type": "Visualization", "release_date": "1994-04-29T12:00:00-04:00", "title": "Ocean Planet: Final Version", "description": "The Ocean Planet is a traveling exhibition from the Smithsonian Institution which opened in Washington DC on April 22, 1995. A part of the exhibition was a computer flyby of the Pacific Ocean developed in the SVS. This animation represents a stage in the development of that flyby. || ", "hits": 59 } ] }