Astronomy with SalsaJ

Volcanos and craters in the Solar System

Scaling the planets 

In this activity, images of volcanoes and craters in the Solar system will be examinated using the software SalsaJ. Measurements of the size of craters and ejecta will be possible. 


Volcanos and craters in the Solar System

      This activity was initially prepared by Marie-Christine Angonin, Jérémie Lasue and Anne-Laure Melchior for students following modules of methodology in bioastronomy, proposed in the 1st year of Licence at the University Pierre and Marie Curie. It is also suited for pupils of secondary schools, but requires to spend a longer period. It has been tested in a scientific workshop (level 5th and 4th -- 12-13 years old) at the middle school named "Vieux Colombier" at Le Mans.

  It uses the SalsaJ software.

enceladusfountains 116.84 Kb

g2io_i24_i25_i27small 100.14 Kb

io1 221.35 Kb

io_coule_lave 1.07 Mb

io_plume_1 26.18 Kb

olympe 64.14 Kb

: 134 Kb  


Study of volcanic phenomena in the Solar System
Practical works of astronomical imaging. 


 I - Study of a volcano on Io

images needed :
IO plume 1.jpg

 Open the g2io_i24...small..jpg image 

1: Observe the trajectory of the spacecraft, which is observing  Io,  the Jupiter satellite.

2: Explain the nickname of "pizza-pie of space"

     Open the image io_prometheus.fts (File/Open Image). (Credit: NASA.). It is about the observation of an eruption of the Prometheus crater on Io (the nearest galilean satellite of Jupiter) by the probe Galileo on June 28, 1997. The same area observed by the Voyager's probe in 1979 presented already signs of volcanic activity, it is possible that this volcano has been in eruption for more than 18 years

1: Describe this image.

2: Knowing that Io  diameter is  3.630 km, determine the height and the extension of the plume of the observed  eruption.

    Open image:  IO plume1.jpg (credit ESA/NASA). This image (false colors) was taken by the probe "Galileo" on July 3, 1999, at an altitude of approximately 130 km. The resolution is 1,3 km per pixel. One can observe a gas plume and particles ejected under the effect of the volcanicity of the Io moon.

3: Describe this image.  Compare with the preceding one.

4: Determine the height and the extension of the plume of this eruption.

5: Since the volcanos on Earth have plumes which can go up at an altitude of 15-20 km, compare the eruptions on Earth and Io.


II - Another volcano on Io


  images needed:
Io 1.jpg
    Open image IO 1.jpg (credit ESA/NASA). It is about an eruption in an area of  Io which was named " Tvashtar Catena". This image shows the quick change of  an active lava flow; it confirms this observation, made since the Earth , and allows  to suppose:  the matter jets seen on the preceding images are well caused by volcanic eruptions.

1: Observe the two images;  describe the ground. Explain how the active lava flows evolved/moved between the two dates.

2: Evaluate the resolution of the image of right-hand side. Deduce of it  the distance between the two active lava flows. 


 III - Study of a volcano over Mars Images used


images needed:

    Open the image olymons face.fts (Credit: ESA/NASA.). It is about Olympus Mons, largest of the Martian volcanos and also largest known in the Solar system; it is located close to the equator of Mars.Its  height is  26.000 m.

1: Describe the image.

2: By observing the indications of size of image (in top on the left), evaluate the resolution of this digital photograph. Then estimate the diameter of the volcano and the size of its caldera (crater).

3: Use the image olymonsprofile.fts to measure the height of caldera. Discuss.

4: Compare with Mauna leasing with Hawaii (alt. 4170 m) which is the largest terrestrial volcano, whose last eruption goes back to 1984. Its measurement is 3km x  5 km for a caldera depth,  approximately 180 m.


IV - Mystery on Encelade


  images needed:
encelade 2.jpg

    Open the image encelade (Credit: ESA/NASA.). It is about an image of the Saturn satellite called Encelade. Approximately two weeks ago, Simon heard following information, of American origin: "a volcanic phenomenon was highlighted on the satellite Encelade de Saturne"; the Cassini probe sent images of what could be geysers... until now the scientists had  thought that only the Earth and Io were the seat of active volcanic phenomena...

1: Describe the surface of this satellite

2: Measure its diameter after having evaluated the resolution of the image

    Open the image enceladusfountains.jpg (Credit ESA/NASA). It is about a "crescent of the moon", photographed by the Cassini probe

1: Describe what you see

2: Measure the size of the plumes. Compare with the size of Encelade