Jupiter
Cloud bands are clearly visible on Jupiter. Credit: NASA/JPL/USGS.

Jupiter is the largest planet in the Solar System and contains nearly 3/4 of all planetary matter.

With no solid surface, Jupiter is a gas and liquid filled giant. Its turbulent belts of clouds circulate parallel to the equator and often contain oval spots which are storm systems with the largest being easily twice the diameter of Earth. The great red spot has been observed for at least 300 years and rotates counter-clockwise with wind speeds of 270 miles per hour [430 km/hr].

Although observed and studied from Earth for centuries it wasn't until the mid 1970's that humans were able to get a closer look with the spacecraft Pioneer 10 and 11. The Voyager 1 and 2 spacecraft were launched with the specific purpose of collecting information and data on the Jovian worlds. In December 1995 the Galileo spacecraft entered into orbit and began it's long-term study of Jupiter and it's moons, a probe was also sent deep into the atmosphere of the gas giant.

Selected radiation astronomy

Radios

This VLA image of Jupiter doesn't look like a planetary disk at all. Credit: NRAO.

In 1955, Bernard Burke and Kenneth Franklin detected bursts of radio signals coming from Jupiter at 22.2 MHz.[1] The period of these bursts matched the rotation of the planet, and they were also able to use this information to refine the rotation rate. Radio bursts from Jupiter were found to come in two forms: long bursts (or L-bursts) lasting up to several seconds, and short bursts (or S-bursts) that had a duration of less than a hundredth of a second.[2]

Forms of decametric radio signals from Jupiter:

  • bursts (with a wavelength of tens of meters) vary with the rotation of Jupiter, and are influenced by interaction of Io with Jupiter's magnetic field.[3]
  • emission (with wavelengths measured in centimeters) was first observed by Frank Drake and Hein Hvatum in 1959.[1] The origin of this signal was from a torus-shaped belt around Jupiter's equator. This signal is caused by cyclotron radiation from electrons that are accelerated in Jupiter's magnetic field.[4]

Between September and November 23, 1963, Jupiter is detected by radar astronomy.[5]

"The dense atmosphere makes a penetration to a hard surface (if indeed one exists at all) very unlikely. In fact, the JPL results imply a correlation of the echo with Jupiter ... which corresponds to the upper (visible) atmosphere. ... Further observations will be needed to clarify the current uncertainties surrounding radar observations of Jupiter."[5]

"Although in 1963 some claimed to have detected echoes from Jupiter, these were quite weak and have not been verified by later experiments."[6]

"A search for radar echoes from Jupiter at 430 MHz during the oppositions of 1964 and 1965 failed to yield positive results, despite a sensitivity several orders of magnitude better than employed by other groups in earlier (1963) attempts at higher frequencies. ... [I]t might be suspected that meteorological disturbances of a random nature were involved, and that the echoes might be returned only in exceptional circumstances. Further support for this point of view may be gleaned from the fact that JPL found positive results for only 1 (centered at 32° System I longitude) of the 8 longitude regions investigated in 1963 (Goldstein 1964) and, in fact, had no success during their observations in 1964 (see comment by Goldstein following Dyce 1965)."[7]

"This VLA image of Jupiter [at right] doesn't look like a planetary disk at all. Most of the radio emission is synchrotron radiation from electrons in Jupiter's magnetic field."[8]

References

  1. 1.0 1.1 Linda T. Elkins-Tanton (2006). Jupiter and Saturn. New York: Chelsea House. ISBN 0-8160-5196-8. 
  2. Weintraub, Rachel A. (26 September 2005). How One Night in a Field Changed Astronomy. NASA. http://www.nasa.gov/vision/universe/solarsystem/radio_jupiter.html. Retrieved 18 February 2007. 
  3. Garcia, Leonard N. The Jovian Decametric Radio Emission. NASA. http://radiojove.gsfc.nasa.gov/library/sci_briefs/decametric.htm. Retrieved 18 February 2007. 
  4. Klein, M. J.; Gulkis, S.; Bolton, S. J. (1996). Jupiter's Synchrotron Radiation: Observed Variations Before, During and After the Impacts of Comet SL9. NASA. http://deepspace.jpl.nasa.gov/technology/TMOT_News/AUG97/jupsrado.html. Retrieved 18 February 2007. 
  5. 5.0 5.1 Gordon H. Pettengill & Irwin I. Shapiro (1965). "Radar Astronomy". Annual Review of Astronomy and Astrophysics 3: 377-410. 
  6. Irwin I. Shapiro (March 1968). "Planetary radar astronomy". Spectrum, IEEE 5 (3): 70-9. doi:10.1109/MSPEC.1968.5214821. http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=5214821. Retrieved 2012-12-25. 
  7. R. B. Dyce and G. H. Pettengill, and A. D. Sanchez (August 1967). "Radar Observations of Mars and Jupiter at 70 cm". The Astronomical Journal 72 (4): 771-7. doi:10.1086/110307. http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1967AJ.....72..771D&data_type=PDF_HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf. Retrieved 2012-12-25. 
  8. S.G. Djorgovski (16 March 2016). A Tour of the Radio Universe. National Radio Astronomy Observatory. http://www.cv.nrao.edu/course/astr534/Tour.html. Retrieved 16 March 2014. 
Selected topic

Electrons

"Field-aligned equatorial electron beams [have been] observed within Jupiter’s middle magnetosphere. ... the Jupiter equatorial electron beams are spatially and/or temporally structured (down to <20 km at auroral altitudes, or less than several minutes), with regions of intense beams intermixed with regions absent of such beams."[1]

"Jovian electrons, both at Jupiter and in the interplanetary medium near Earth, have a very hard spectrum that varies as a power law with energy (see, e.g., Mewaldt et al. 1976). This spectral character is sufficiently distinct from the much softer solar and magnetospheric electron spectra that it has been used as a spectral filter to separate Jovian electrons from other sources ... A second Jovian electron characteristic is that such electrons in the interplanetary medium tend to consist of flux increases of several days duration which recur with 27 day periodicities ... A third feature of Jovian electrons at 1 AU is that the flux increases exhibit a long-term modulation of 13 months which is the synodic period of Jupiter as viewed from Earth".[2]

Hypotheses

  1. Jovian electrons are at a maximum irradiating the Sun at solar activity maximum.
  2. Venusian electrons are at a maximum irradiating the Sun at solar activity maximum per the conjunction with Jupiter at periapsis.

References

  1. Barry H. Mauk and Joachim Saur (October 26, 2007). "Equatorial electron beams and auroral structuring at Jupiter". Journal of Geophysical Research 112 (A10221): 20. doi:10.1029/2007JA012370. http://www.agu.org/journals/ja/ja0710/2007JA012370/figures.shtml. Retrieved 2012-06-02. 
  2. C. T. Russell, D. N. Baker and J. A. Slavin (January 1, 1988). Faith Vilas. ed. The Magnetosphere of Mercury, In: Mercury. Tucson, Arizona, United States of America: University of Arizona Press. pp. 514-61. ISBN 0816510857. Bibcode: 1988merc.book..514R. http://www-ssc.igpp.ucla.edu/personnel/russell/papers/magMercury.pdf. Retrieved 2012-08-23. 
Selected astronomy

Water astronomy

Jupiter is imaged with the Stockholm Infrared Camera (SIRCA) in the H2O band. Credit: M. Gålfalk, G. Olofsson and H.-G. Florén, Nordic Observatory Telescope (NOT).

At center is a significant observation of Jupiter in the H2O band using the Stockholm Infrared Camera (SIRCA) on the Nordic Observatory Telescope (NOT).

The image clearly shows that water vapor is plentiful in the Jovian atmosphere.

Selected deity

Zeus

Zeus and his eagle are the statue. Credit: Marcus Cyron.{{free media}}

In the ancient Greek religion, Zeus (Ancient Greek is the "Father of Gods and men". He is the god of sky and thunder in Greek mythology. His Roman counterpart is Jupiter and Etruscan counterpart is Tinia. Zeus is the child of Cronus and Rhea, and the youngest of his siblings. In most traditions he is married to Hera, although, at the oracle of Dodona, his consort is Dione: according to the Iliad, he is the father of Aphrodite by Dione.

Selected image

Jupiter is imaged with the Stockholm Infrared Camera (SIRCA) in the H2O band. Credit: M. Gålfalk, G. Olofsson and H.-G. Florén, Nordic Observatory Telescope (NOT).

The image clearly shows that water vapor is plentiful in the Jovian atmosphere.

Selected meteor

Storms

This image of Jupiter is produced from a 2x2 mosaic of photos taken by the New Horizons Long Range Reconnaissance Imager (LORRI). Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.{{free media}}

"This image of Jupiter is produced from a 2x2 mosaic of photos taken by the New Horizons Long Range Reconnaissance Imager (LORRI), and assembled by the LORRI team at the Johns Hopkins University Applied Physics Laboratory. The telescopic camera snapped the images during a 3-minute, 35-second span on February 10, when the spacecraft was 29 million kilometers (18 million miles) from Jupiter. At this distance, Jupiter's diameter was 1,015 LORRI pixels -- nearly filling the imager's entire (1,024-by-1,024 pixel) field of view. Features as small as 290 kilometers (180 miles) are visible."[1]

"Both the Great Red Spot and Little Red Spot are visible in the image, on the left and lower right, respectively. The apparent "storm" on the planet's right limb is a section of the south tropical zone that has been detached from the region to its west (or left) by a "disturbance"".[1]

"At the time LORRI took these images, New Horizons was 820 million kilometers (510 million miles) from home -- nearly 5½ times the distance between the Sun and Earth."[1]

References

  1. 1.0 1.1 1.2 Sue Lavoie (2 April 2007). PIA09243: Full Jupiter Mosaic. Pasadena, California USA: NASA/JPL. https://photojournal.jpl.nasa.gov/catalog/PIA09243. Retrieved 29 June 2018. 
Selected moon

Europa

This image shows two views of the trailing hemisphere of Jupiter's ice-covered satellite, Europa. The left view shows the approximate natural color appearance of Europa. Credit: NASA/Deutsche Forschungsanstalt für Luft- und Raumfahrt e.V., Berlin, Germany.

The image is a composite of two views of Europa. The left view shows the approximate natural color appearance of Europa. The view on the right is a false-color composite version combining violet, green and infrared images to enhance color differences in the predominantly water-ice crust of Europa. Dark brown areas represent rocky material derived from the interior, implanted by impact, or from a combination of interior and exterior sources. Bright plains in the polar areas (top and bottom) are shown in tones of blue to distinguish possibly coarse-grained ice (dark blue) from fine-grained ice (light blue). Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long. The bright feature containing a central dark spot in the lower third of the image is a young impact crater some 50 kilometers (31 miles) in diameter. This crater has been provisionally named "Pwyll" for the Celtic god of the underworld. This image was taken on September 7, 1996, at a range of 677,000 kilometers (417,900 miles) by the solid state imaging television camera onboard the Galileo spacecraft during its second orbit around Jupiter.

Selected theory

Radiative dynamos

This is a diagram of the dynamo within Jupiter producing its axisymmetric dipole magnetic field. Credit: Robert MacDowall, Planetary Magnetospheres Laboratory, Code 695, GSFC, NASA.

"The interior of Jupiter is the seat of a strong dynamo that produces a surface magnetic field in the equatorial region with an intensity of ~ 4 Gauss. This strong magnetic field and Jupiter’s fast rotation (rotation period ~ 9 h 55 min) create a unique magnetosphere in the solar system which is known for its immense size (average subsolar magnetopause distance 45-100 RJ where 1 RJ = 71492 km is the radius of Jupiter) and fast rotation [...]. Jupiter’s magnetosphere differs from most other magnetospheres in the fact that it derives much of its plasma internally from Jupiter’s moon Io. The heavy plasma, consisting principally of various charge states of S and O, inflates the magnetosphere from the combined actions of centrifugal force and thermal pressure."[1]

In "the absence of an internal heavy plasma, the dipole field would balance the average dynamic pressure of the solar wind (0.08 nPa) at a distance of ~ 42 RJ in the subsolar region [...] the observed average magnetopause location of ~ 75 RJ [...] The heavy plasma is also responsible for generating an azimuthal current exceeding 160 MA in the equatorial region of Jupiter’s magnetosphere where it is confined to a thin current sheet (half thickness ~ 2 RJ in the dawn sector)."[1]

"The energization of plasma by various electrical fields as it diffuses inwards is responsible for the creation of radiation belts in the inner magnetosphere of Jupiter. It is believed that the radial diffusion is driven by the ionospheric dynamo fields produced by winds in Jupiter’s atmosphere"[1]

"In situ and remote observations of Io and its surroundings from Voyager showed that Io is the main source of plasma in Jupiter’s magnetosphere [...] "[1]

"It is estimated that upward of 6 × 1029 amu/s (~ 1 ton/s) of plasma mass is added to the magnetosphere by Io. The picked-up plasma consists mostly of various charged states of S and O and populates a torus region extending from a radial distance of ~ 5.2 RJ to ~ 10 RJ."[1]

"The next most important source of plasma in Jupiter’s magnetosphere is the solar wind whose source strength can be estimated by a consideration of the solar wind mass flux incident on Jupiter’s magnetopause and the fractional amount that makes it into the magnetosphere (< 1%). Such a calculation suggests that the solar wind source strength is < 100 kg/s (Hill et al. 1983) considerably lower than the Io source. Nevertheless, the number density of protons (as opposed to the mass density) may be comparable to the iogenic plasma number density in the middle and outer magnetospheres where the solar wind may be able to gain access to the magnetosphere."[1]

"The escape of ions (mainly H+ and H2+ ) from the ionosphere of Jupiter provides the next significant source of plasma in Jupiter’s magnetosphere. The ionospheric plasma escapes along field lines when the gravity of Jupiter is not able to contain the hot plasma (~ 10 eV and above). The escape however is not uniform and depends on the local photoelectron density, the temperature variations of the ionosphere with the solar zenith angle, other factors such as the auroral precipitation of ions and electrons and the ionospheric heating from Pedersen currents. In situ measurements show that in Io’s torus, protons contribute to less than 20% of total ion number density and constitute < 1% of mass suggesting that the ionosphere is not a major source of plasma in Jupiter’s magnetosphere. [The] ionospheric source strength [is] in the range of ~ 20 kg/s."[1]

The "surface sputtering of the three icy satellites by jovian plasma provides the last significant source of plasma in Jupiter’s magnetosphere. Because the icy moons lack extended atmospheres and the fluxes of the incident plasma are low at the locations of these moons, the total pickup of plasma from these satellites is estimated to be less than 20 kg/s based on the plasma sputtering rates provided".[1]

"Other minor constituents found in the torus [...] were Na+ (with an abundance of < 5%) and molecular ions SO+ and SO2+ (both with abundances of < 1% of the total). The average mass of a torus ion is ~ 20 and the average fractional charge on an ion is ~ 1.2 [...]. The bulk velocity of the plasma was found to be ~ 75 km/s, close to the corotational value."[1]

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Krishan K. Khurana; Margaret G. Kivelson; Vytenis M. Vasyliunas; Norbert Krupp; Joachim Woch; Andreas Lagg; Barry H. Mauk; William S. Kurth (2004). Bagenal, F.. ed. The Configuration of Jupiter’s Magnetosphere, In: Jupiter: The Planet, Satellites and Magnetosphere. Cambridge University Press. pp. 24. ISBN 0-521-81808-7. http://www.igpp.ucla.edu/people/mkivelson/Publications/279-Ch24.pdf. Retrieved 2014-03-29.