Surface height distribution for Jupiter's moon Io?

Surface height distribution for Jupiter's moon Io?

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The moon Io has around 100 mountains:

These structures average $6 { m, km}$ in height and reach a maximum of ${ m 17.5 pm 1.5, km}$

I am now looking for the overall histogram, i.e. elevation distribution of Io's surface and/or a hypsometric curve for Io.


  • JPL: Topography of Io

This blog by Butcher and Conwey on Geomorphology (or should we say io-morphology?) was a good starter. It seems usual to deal with the distribution of mountains and volcanos on Io. There are height maps (DEM) which give the distribution colour-coded. The closes to a hysometric curve found for Io is in this paper by White et al (2014) which gives a hypsometric curve where they exclude the volcanos in figure 9.

Noteworthy might also be this poster by Wiliams et al with geological map but also a height distribution given single measurement "points" (where the points are areas of various size).

14.5 Planetary Evolution

While we await more discoveries and better understanding of other planetary systems, let us look again at the early history of our own solar system, after the dissipation of our dust disk. The era of giant impacts was probably confined to the first 100 million years of solar system history, ending by about 4.4 billion years ago. Shortly thereafter, the planets cooled and began to assume their present aspects. Up until about 4 billion years ago, they continued to acquire volatile materials, and their surfaces were heavily cratered from the remaining debris that hit them. However, as external influences declined, all the terrestrial planets as well as the moons of the outer planets began to follow their own evolutionary courses. The nature of this evolution depended on each object’s composition, mass, and distance from the Sun.


Jupiter's moon Io is the only other body in the solar system known to have active, high-temperature volcanism like that found on Earth. The Galileo spacecraft has been observing Io regularly since June 1996, and the data that it has returned have led to many new insights into the volcanic processes that have shaped not only Io, but Earth in its distant past.

To a volcanologist, Io is a paradise. The discovery of active volcanism on Io by the Voyager spacecraft ( Smith 1979) was the first extraterrestrial case of a process that constantly reshapes the surface of the Earth. Io is the most volcanically active body in the solar system, as a result of tidal heating: Io is caught in a gravitational tug-of-war between Jupiter and Europa ( Peale 1979), and the intense heating manifests itself as widespread volcanism.

Since it began making observations of the Galilean satellites in June 1996, the spacecraft Galileo has produced extraordinary images of volcanism on Io, collected a wealth of data concerning thermal emission and composition, and greatly advanced what is known about this highly volcanic satellite. Observing Io's volcanism, studying thermal output and eruption evolution, determining lava composition and measuring the resulting geomorphology were major objectives of the Galileo mission, building on the data collected by the Voyager spacecraft and continuing the monitoring of volcanic activity from ground-based telescopes (see, for example, Veeder 1994) augmented by Hubble Space Telescope observations (e.g. Spencer 2000a). In this paper the extraordinary discoveries pertaining to Io's volcanism made during the Galileo epoch are reviewed.

Saturday, March 16, 2013

See Jupiter and Moon Pair Up on St. Patrick's Day

On Sunday evening, revelers can cap their St. Patrick's Day by enjoying a view of a rendezvous involving two of the brightest objects in the night sky: the moon and the planet Jupiter .

About 45 minutes after sunset on Sunday (March 17), the eye-catching celestial duo will be visible in the southwest sky, roughly two-thirds up from the horizon to the point directly overhead (called the zenith).

The moon will be a wide crescent at the time, 34 percent illuminated by the sun, and will sit below Jupiter . At its closest pass - which will occur at around 10:30 p.m. local daylight time along the U.S. East Coast, and around 7:00 p.m. local time for the West Coast - Earth's natural satellite will be just 2 degrees from the giant planet. (For reference, your clenched fist held at arm's length measures about 10 degrees.)

After its closest approach, the moon, moving at its own apparent diameter per hour, will appear to slowly move away from Jupiter to the east (left). [Amazing Night Sky Photos by Stargazers (March 2013)]

Even without the moon, Jupiter readily attracts attention. It's the brightest 'star' of the night, coming into view high in the southwest during the early stages of twilight. The first-magnitude star Aldebaran flickers into view next, about 5 degrees to the lower left of Jupiter, its orange color helping it to stand out from the deepening dark-blue sky.

Last to appear are the famous Pleiades and Hyades star clusters as the sky darkens from purple to black. The entire array of the moon, planet, bright star and star clusters sits within the constellation of Taurus (The Bull).

Binoculars are perfect for observing the whole Taurus get-together. Even the most ordinary pair will show dozens of Pleiades and Hyades stars, and at least one, two, or three of Jupiter's four bright Galilean moons (Ganymede, Callisto, Io and Europa).

Be sure to check out Jupiter on the evening of March 24, when any small telescope will show it closely flanked above and below by two seventh-magnitude background stars in Taurus, masquerading as an extra pair of renegade Galilean satellites.

In a telescope, Jupiter is best observed during early evening when it's still high and its image reasonably calm. Viewing at such times shows the king of planets as a great big belted ball with tantalizing glimpses of detail.

As the evening grows late, the whole assemblage wheels lower in the west and sets soon after midnight.

Missions to Jupiter

Since Galileo first laid telescope-enhanced eyes on Jupiter, scientists have continued to study the curious world from both the ground and the sky. In 1979, NASA's Voyager 1 and 2 spacecraft zipped by the gas giant, taking tens of thousands of pictures as they passed by. Among the surprises from these missions, the data revealed that giant Jupiter sports thin, dusty rings.

And when NASA's Juno spacecraft began orbiting Jupiter in 2016, it quickly started sending back breathtaking images. The stunning pictures revealed that the planet is even more wild than we once thought. Juno returned some of the first detailed looks at the planet's poles, which revealed cyclone swarms gyrating on its surface with roots that likely extend deep below the upper bands of clouds.

Though Jupiter has been so intensely examined, many mysteries remain. One enduring question is what drives Jupiter's Great Red Spot, and what will happen to it in the future. Then there's the question of what actually lies at Jupiter's core. Magnetic field data from the Juno spacecraft suggest that the planet's core is surprisingly large and seems to be made of a partially dissolved solid material. Whatever that is, it's searing hot. Scientists estimate the temperature in this region could be up to 90,032 degrees Fahrenheit—hot enough to melt titanium.

4. Theory of Auroral Hiss Propagation

[10] Consider now a point that is radiating whistler mode waves along the resonance cone at a ray path angle ψ relative to the magnetic field B0 as shown in the upper panel of Figure 6. It is obvious from equation (4) that the angles of the ray path relative to the magnetic field increase with frequency. As a spacecraft approaches the radiation source from left, the highest radiation frequency f3 is then received first, followed by lower and lower frequencies, i.e., f2 and f1. The resulting frequency time variation is shown by the curved V-shaped lines in the bottom panel of Figure 6. If instead of a point source, the radiation is generated by a line source that extends upward along the magnetic field from the point marked “source,” the result will be a frequency time spectrum that is filled in as shown by the shaded region. A field-aligned sheet source also leads to a filled-in spectrum, although the detailed intensity distribution within the filled-in region will be different than for a line source. Note that the existence of the low-frequency cutoff is related to the fact that the source has a sharply defined lower boundary.


All in all, Miranda is one of the smaller moons that orbits the planet Uranus. It has the largest known cliff in our solar system, and it has a mixture of both old craters surface and well as a younger surface too. Hopefully you’ve learned a little more about the moon Miranda!

About Derek

Hey! I'm Derek, I've been interested in astronomy since.. well, forever! I'm an engineer by trade, but I've been playing around with telescopes for many years. I hope to impart some of the knowledge I've learned over the years onto you!

The seventh wonder of the world

Europa is a moon of Jupiter, the sixth largest moon of the solar system just after our Moon. Its surface is smooth and shiny and just the beauty of Europa comes from its enigmatic surface fractured.
Europa have a gigantic ocean of salt water, kept liquid, hidden under a frozen surface of several kilometers.
Fractures of ice crust show the friction generated by the enormous tidal forces of Jupiter. In places, cracks allow the upwelling groundwater '. These cracks open and close constantly hiding inside a "hot". Moreover, its atmosphere contains little oxygen and the surface of Europa seems to harbor organic elements.
The ice crust is torn by long and wide dark bands that show a deformation of the surface. This surface takes the form of a vast network of interwoven fractures, sprinkled with hydrated magnesium and sodium sulfates and possibly sulfuric acid. These traces betray the presence of underground water. Europa like Earth consists of an iron core, a rocky mantle and a saltwater ocean beneath its icy crust.

As far from the sun, the ocean would be completely frozen. But Europa orbits Jupiter in 3.5 days, and the moon is locked by gravity, always showing the same face to Jupiter.
Its proximity to the giant Jupiter creates tides that stretch and relax its surface. Tides provide energy to the ice moon envelope, creating linear fractures visible through its surface. If the ocean of Europa are the tides could also create volcanic or hydrothermal activity on the seafloor, providing nutrients. From there, everything is possible, even the ocean could harbor life.
In 2013, the Hubble Space Telescope spotted plumes of water into space, which generated considerable excitement among scientists, because it proves that the moon is still geologically active.
These feathers of liquid water will be studied by future missions to Europa, particularly that NASA will start in 2020 and that already fascinate the scientific world.
Europa is the most promising place in the solar system for the search for life.

Evidence of an Active Planet

Why do Pluto and Charon have so few craters? Naturalistic astronomers don’t believe that Pluto itself is young, but that the surface is young. How can the surface be young but not Pluto itself? Their assumption is that material spewed from recent geological activity must have covered many craters.

Furthermore, some of the ice on Pluto’s surface appears to have moved in what amounts to glacial activity. This is not the sort of thing that one would expect on an old, dead world, either.

There are signs of other recent geological activity. Towering mountain ranges on Pluto rival the Rockies in height. High mountains tend to sink back down under their own weight, something that should have happened long ago if the mountains are old. The process of leveling would be speeded up if Pluto’s interior has liquid water, which some planetary scientists are now claiming, based upon certain icy surface features.

What is responsible for Pluto’s geological activity? Astronomers think that this can happen one of two ways. One possibility is an internal source of heat. For instance, some suggest it may be like the earth, which has radioactive materials inside the planet that generate heat as they decay. Most scientists think this process keeps the earth hot inside. This will not work for Pluto, however. Pluto does not appear to have radioactive materials, which would make it very dense. Its density is very low, less than half the density of the earth. This low density is consistent with Pluto being a mixture of ice and rock. These rocks would not have sufficient radioactivity to heat Pluto for billions of years.

A second heating mechanism could be tidal flexing. Large astronomical objects can stretch and squeeze their smaller neighbors. Astronomers have invoked this process to explain why no craters exist on the surface of Io, the innermost large satellite of Jupiter. They say that Jupiter has caused tidal flexing on Io, generating many volcanoes that periodically recover Io’s surface. Alternately stretching and compressing with each orbit, Io’s interior continually heats up, much as a metal wire heats up when we bend it rapidly back and forth. With the vast difference in size between Jupiter and Io, tidal flexing seems like a reasonable explanation for Io’s smooth surface, though doubt remains whether this mechanism is strong enough to explain Io’s volcanism. This mechanism may work on Io, but it cannot work at all on Pluto. No massive bodies orbit nearby.

With both possibilities eliminated, how do astronomers explain the surfaces of Pluto and Charon? No explanation has been forthcoming yet. Astronomers may eventually suggest that Pluto and Charon just happened to have experienced some rare, catastrophic event recently (in the past few hundred million years). However, blaming a rare event amounts to an arbitrary rescuing device. It cannot be proven, so it hardly constitutes science.