... SUN MOON MERCURY VENUS MARS, JUPITER SATURN . ... Mars . ... Previously understood that magnetic fields were directly related to rotation, so when I read that Mars, like Venus, didn't have one, my understanding crumbled. What exactly causes magnetic fields in planets? ... RELATED TOPICS: MAGNETIC FIELD . Planetary magnetic fields are definitely related to rotation, but directly not so much. ... Get instant access to subscriber content on Astronomy.com! ...

Jupiter's volcano-pocked moon Io has been found by NASA's Galileo spacecraft to have a giant iron core that takes up half its diameter, scientists report in today's issue of Science magazine. The spacecraft also has detected a large "hole" in Jupiter's magnetic field near Io, leading to speculation about whether Io possesses its own magnetic field. ... Galileo scientists also are trying to determine the cause of the hole they found in Jupiter's magnetic field when the spacecraft was closest to Io. ...

... Artist?s conception of the collision of Comet Shoemaker-Levy 9 with Jupiter, as seen from the Galileo spacecraft. At the time of the first impact, the comet fragments will be much farther apart than shown in this illustration. ... One orbit, computer May 18, 1993 by Syuichi Nakano, showed that the comet passed close to Jupiter in July 1992, and would pass within 45,000 kilometers of the center of Jupiter in July, 1994. ... The fragments of Shoemaker-Levy 9 move around Jupiter. ...

Galileo Crosses Boundary Into Jupiter's Environment . NASA's Galileo spacecraft radioed confirmation late this week that it has entered Jupiter's environment, crossing over the boundary from interplanetary space into the giant magnetic cocoon around Jupiter called the magnetosphere. ... On Thursday, December 7, Galileo's previously deployed atmospheric probe will plunge into Jupiter's cloud tops at 5:56 p.m. EST and descend into the giant planet on a parachute. ... Space History Galileo . ...

... A dynamo is created in a magnetic field by an electric circuit, part of which is moving relative to the rest (additional conditions must also be met). ... Furthermore, the plasma between them conducts electricity very well along its magnetic field lines, which act as if they were wires connecting Io and the planet (drawing). ... The drawing is not to scale. ... The Hubble Space Telescope , using its Wide Field and Planetary Camera 2, has been photographing auroras of the planet Jupiter. ...

Most of the stars in the local Universe inhabit spiral galaxies (like our own Milky Way) or elliptical galaxies. ... The nearest elliptical galaxy is M32, at a distance of 770,000 parsec (2.5 million light years). ... Our image of M32 is the first to directly image the stars responsible for the ultraviolet light produced by elliptical galaxies. ... The image below shows how M32 appears in near-ultraviolet light. ... A false-color JPEG file of the STIS near-UV M32 image is available here . ...

... They are concerned with Attitude Control System of the spacecraft, satellite visibility from tracking stations, limits on the satellite autonomous operations during the orbit, and needs for auxiliary operations with the spacecraft. ... Among the operational constraints the most important one is the number of programmed slews per orbit, which determines the maximum number of radio sources to be observed during one orbit. ... System temperature (K) . ... Progress of the RadioAstron Project in Pictures...

... Armagh Observatory, College Hill, Armagh BT61 9DG, +44 (0)28 3752 2928 . ... Risks Comparable to NEOs . ... The Increasing Rate of Discovery of Asteroids . ... Comet and Asteroid Collision Probabilities . ... Extreme albedo comets and the impact hazard (PDF Format) . ... Asteroid Impact Animations . ... Workshop on Scientific Requirements for Mitigation of Hazardous Comets and Asteroids - 2002 . ... The Spaceguard Survey Report, 1992 (PDF) . Tsunami from Asteroid/Comet Impacts . ...

The following images of the icy surface of Ganymede, the Solar System's largest moon, were made by the Galileo spacecraft during its ongoing mission to explore Jupiter and the Jovian system. ... This image was taken when Galileo was 7,448 kilometers (4,628 miles) away from Ganymede; north is to the top of the picture, and sunlight illuminates the surface from the lower left nearly overhead (77 degrees above the horizon). ... The image was taken June 27 at a range of 7,448 kilometers (4,628 miles). ...

... Bad Astronomy . ... Bitesize Astronomy . ... Bad Astro Store . ... Slacker Astronomy . ... Keep Bad Astronomy close to your heart, and help make me filthy rich. ... Life Under the Moon . ... Seeing Jupiter's Moons . ... Time Zones and the Spherical Earth . A Companion to the Earth? ... December 19, 1999) . ... Big Moon, Little Moon . ... How Big is the Moon? ... 14, 2000) . ... 2008 Phil Plait. ... Subscribe to the Bad Astronomy Newsletter! Talk about Bad Astronomy on the BA Bulletin Board! ...