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APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 4:06 am
by APOD Robot
Io: The Prometheus Plume
Explanation: What's happening on Jupiter's moon Io? Two sulfurous eruptions are visible on
Jupiter's volcanic moon Io in this color
composite image from the robotic
Galileo spacecraft that orbited Jupiter from 1995 to 2003. At the image top, over
Io's limb, a bluish plume rises about 140 kilometers above the surface of a
volcanic caldera known as
Pillan Patera. In the image middle, near the night/day shadow line, the ring shaped Prometheus plume is seen rising about 75 kilometers
above Io while casting a shadow below the
volcanic vent. Named for
the Greek god who gave mortals
fire, the
Prometheus plume is visible in every
image ever made of the region dating back to
the Voyager flybys of 1979 - presenting the possibility that
this plume has been continuously active for at least 18 years. The above digitally
sharpened image of
Io was originally recorded in 1997 from a distance of about 600,000 kilometers.
Recent analyses of Galileo data has
uncovered evidence of a magma ocean
beneath Io's surface.
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Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 4:24 am
by Beyond
To me, Io still looks like a ball of moldy cheese, but the purple plume looks nice!
![Very Happy :D](./images/smilies/icon_biggrin.gif)
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 4:48 am
by nstahl
Very nice choice.
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 1:06 pm
by biddie67
In the picture of Io, there is an apparent bit of color just below the night/day shadow line at about 7 o'clock from the Prometheus plume. Could this be another vent of some kind?
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 1:31 pm
by neufer
ttp://earthobservatory.nasa.gov/IOTD/view.php?id=50666 wrote:
<<Spanning about 22 kilometers (14 miles), Valles Caldera in New Mexico was formed from the collapse of a magma chamber following ancient volcanic eruptions. The Enhanced Thematic Mapper Plus on Landsat 7 satellite captured this natural-color image of the area on May 22, 2002. Plants have colonized parts of the caldera, which is surrounded by a network of valleys. The city of Los Alamos lies to the east.
Valles Caldera is a complex formation resulting from two high-volume eruptions that occurred during the Pleistocene Epoch. Eruptions about 1.7 million and 1.2 million years ago pushed up magma that was rich with water and granite. When the magma broke through overlying rock layers, its water content turned to steam, driving powerful eruptions that buried the surrounding area in layers of volcanic ash—hundreds of meters thick in some places. As ash and steam billowed overhead, magma under the surface dwindled. In the eruption 1.2 million years ago, a giant rock plug descended into the magma chamber, leaving steep rock walls around its perimeter. Landslides toward the chamber quickly followed. Over thousands of years, however, the caldera floor slowly rose. Today, hot springs and fumaroles persist at Valles Caldera. The volcanic ash that sprayed over the landscape during the Pleistocene later hardened into the Bandelier Tuff. Parts of this porous volcanic rock later became home to Ancestral Pueblo people who carved
cavates. Some of these ancient dwellings are now preserved at Bandelier National Monument.>>
http://asterisk.apod.com/viewtopic.php? ... KI#p133551
http://www.planetaryexploration.net/jupiter/io/loki.html wrote:
<<
Loki is the most powerful volcano in the solar system, and consistently emits more heat than all of Earth's volcanoes combined. Loki has an enormous caldera, larger than the state of Maryland, which is continually flooded with lava. Lava temperatures recorded at the Loki hot spot are similar to those of basaltic lavas on Earth.
Active lava and lava that is still cooling cover the floor of the Loki caldera and surround a light-colored island. With the exception of a narrow crack in the center of the island where high temperatures indicate volcanic activity, the rest of the island appears to be cold. Current volcanic activity can be seen in this temperature map. The yellow regions correspond to temperatures of about 87 degrees Celsius, and the red areas record temperatures of about 157 degrees Celsius. The hottest temperatures correspond to the white areas. Here temperatures reach upwards of 567 degrees Celsius.
Scientists are still trying to determine what kind of volcano Loki is. The high temperatures on the western edge of the caldera support the idea that it is an active lava lake with molten material beneath the crust. In volcanic calderas on Earth, such as Hawaii's Kilauea volcano, the crust that forms on the surface as the lava cools tends to drift outward, eventually hitting the caldera wall. Upon striking the wall, the crust breaks up causing hotter material from below the surface to be exposed. >>
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 5:57 pm
by Boomer12k
I wonder if Jupiter's Ring comes from some of this material, like Saturn's Ring coming from Enceladus.
![Cool 8-)](./images/smilies/icon_cool.gif)
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 7:22 pm
by neufer
Boomer12k wrote:
I wonder if Jupiter's Ring comes from some of this material, like Saturn's Ring coming from Enceladus.
![Cool 8-)](./images/smilies/icon_cool.gif)
http://en.wikipedia.org/wiki/Rings_of_Jupiter wrote:
<<The planet Jupiter has a system of rings, known as the rings of Jupiter or the Jovian ring system. It was the third ring system to be discovered in the Solar System, after those of Saturn and Uranus. It was first observed in 1979 by the Voyager 1 space probe and thoroughly investigated in the 1990s by the Galileo orbiter. It has also been observed by the Hubble Space Telescope and from Earth for the past 23 years. Ground-based observations of the rings require the largest available telescopes.
The Jovian ring system is faint and consists mainly of dust. It has four main components: a thick inner torus of particles known as the "halo ring"; a relatively bright, exceptionally thin "main ring"; and two wide, thick and faint outer "gossamer rings", named for the moons of whose material they are composed: Amalthea and Thebe.
The main and halo rings consist of dust ejected from the moons Metis, Adrastea and other unobserved parent bodies as the result of high-velocity impacts. High-resolution images obtained in February and March 2007 by the New Horizons spacecraft revealed a rich fine structure in the main ring.
In visible and near-infrared light, the rings have a reddish color, except the halo ring, which is neutral or blue in color. The size of the dust in the rings varies, but the cross-sectional area is greatest for nonspherical particles of radius about 15 μm in all rings except the halo. The halo ring is probably dominated by submicrometre dust.
The dust is constantly being removed from the main ring by a combination of Poynting–Robertson drag and electromagnetic forces from the Jovian magnetosphere. Volatile materials, for example ices, evaporate quickly. The lifetime of dust particles in the ring is from 100 to 1000 years, so the dust must be continuously replenished in the collisions between large bodies with sizes from 1 cm to 0.5 km and between the same large bodies and high velocity particles coming from outside the Jovian system. This parent body population is confined to the narrow—about 1000 km—and bright outer part of the main ring, and includes Metis and Adrastea. The largest parent bodies must be less than 0.5 km in size. The upper limit on their size was obtained by New Horizons spacecraft. The previous upper limit, obtained from HST and Cassini observations, was near 4 km. The dust produced in collisions retains approximately the same orbital elements as the parent bodies and slowly spirals in the direction of Jupiter forming the faint (in back-scattered light) innermost part of the main ring and halo ring. The age of the main ring is currently unknown, but it may be the last remnant of a past population of small bodies near Jupiter.
Images from the Galileo and New Horizons space probes show the presence of two sets of spiraling vertical corrugations in the main ring. These waves became more tightly wound over time at the rate expected for differential nodal regression in Jupiter's gravity field. Extrapolating backwards, the more prominent of the two sets of waves is appears to have been excited in 1995, around the time of the impact of Comet Shoemaker-Levy 9 with Jupiter, while the smaller set appears to date to the first half of 1990.>>
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Sun May 22, 2011 11:33 pm
by kwaj87
Why are there never any stars in pictures such as these?
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Mon May 23, 2011 12:28 am
by BMAONE23
kwaj87 wrote:Why are there never any stars in pictures such as these?
Because the reflected light from the surface of the moon or planet would overpower the ccd if the aperture were open long enough to capture stars.
If you wanted to try an experiment, take a digital camera outside on a clear night. With the flash turned off, snap a couple pictures of the night sky with an unlit foreground object in the field of view, then light the foreground object with a bright light source and repeat the process. Then download the pictures and tale a look. Odds are, you will have some stars in the unlit image but none visible in the image with the lit foreground.
The same thing happens if you go out at night and image the 1/4 moon. With a clear night and the moon positioned near a star, take a picture of it. The star won't show up because the camera can't allow enough light to enter to catch the fainter starlight without being overpowered by the moons brightness.
Re: APOD: Io: The Prometheus Plume (2011 May 22)
Posted: Mon May 23, 2011 2:53 am
by NoelC
And keep in mind that, though it may overwhelm the camera, our moon's surface is a quite dark grayish material with about the reflectivity of an asphalt roadway. Such is the brightness of sunlight.
I think the sci fi movie industry has given us a bit of a false view of what things might look like "out there". Who knows, with our amazing eyes we might actually see stars right next to a sunlit orb. But cameras don't.
Some years ago I took a very high resolution image of the moon, with data so good I could bring out the various colors of the lunar surface through digital processing. It was stunningly sharp and colorful, but the whole image looked kind of bland until I digitally combined it with stars from another set of exposures that were MUCH longer. THAT resultant image went viral.
-Noel